|Publication number||CA2600529 C|
|Application number||CA 2600529|
|Publication date||7 Aug 2012|
|Filing date||10 Mar 2006|
|Priority date||10 Mar 2005|
|Also published as||CA2600526A1, CA2600529A1, CN101194129A, CN101194129B, CN101208563A, CN101208563B, EP1856453A2, EP1856453A4, EP1856453B1, EP1856454A2, EP1856454A4, EP1856454B1, US8147302, US20060234621, US20070082601, WO2006099125A2, WO2006099125A3, WO2006099337A2, WO2006099337A3|
|Publication number||CA 2600529, CA 2600529 C, CA 2600529C, CA-C-2600529, CA2600529 C, CA2600529C, PCT/2006/8967, PCT/US/2006/008967, PCT/US/2006/08967, PCT/US/6/008967, PCT/US/6/08967, PCT/US2006/008967, PCT/US2006/08967, PCT/US2006008967, PCT/US200608967, PCT/US6/008967, PCT/US6/08967, PCT/US6008967, PCT/US608967|
|Inventors||Eric M. Desrochers, Gordon P. Sharp|
|Applicant||Aircuity, Inc., Eric M. Desrochers, Gordon P. Sharp|
|Export Citation||BiBTeX, EndNote, RefMan|
|Classifications (23), Legal Events (1)|
|External Links: CIPO, Espacenet|
MULTIPOINT AIR SAMPLING SYSTEM HAVING COMMON SENSORS TO
PROVIDE BLENDED AIR QUALITY PARAMETER INFORMATION FOR
MONITORING AND BUILDING CONTROL
This invention relates to air monitoring systems and methods involving the use of 6 multipoint air sampling systems and in some cases discrete local air quality parameter sensors 7 to sense a plurality of air quality parameters to provide blended air quality information and or 8 control signals particularly involving the sensing of humidity and or carbon dioxide. This 9 apparatus and methods can be applied for both monitoring buildings and the control of 1o building functions generally related to regulating an environmental parameter or some aspect i1 of the operation of a building's ventilation system. Specific preferred control embodiments 12 relate at a space or room level to the control of room supply or return air for the dilution 13 ventilation control of spaces or rooms plus the monitoring and control of relative humidity in 14 spaces. At a building or air handling unit level, preferred embodiments relate to the control of the outside airflow into a building for reducing contaminant levels and meeting occupancy i6 based outside airflow requirements as well as the control of outside air using an economizer 17 type approach for operating an air handling unit to enable free cooling with outside air using 18 enthalpy and air contaminant measurements.
As is known in the art, there are various means for monitoring indoor environmental 21 or air quality parameters. One approach involves the use of facility monitoring systems or 22 also referred to as multipoint air monitoring systems. In the context of this invention a 23 multipoint air monitoring system is defined as a monitoring system that includes at least one 24 environmental or air quality parameter sensor that measures at least one air quality parameter for a plurality of rooms, spaces, areas, air ducts, or environments within a building or the 26 ambient conditions surrounding or adjacent to a building or facility. As such a multipoint air 27 monitoring system may involve the use of one or more individual, local, wired or wireless 28 sensors located in the space or area being measured. It may also use remote or centralized air 29 quality parameter sensors that are multiplexed or shared amongst a plurality of spaces as is 3o described in more detail later. Finally, a multipoint air monitoring system may use a 31 combination of the previously mentioned remote and local air quality parameter sensors.
1 Typically, many of these facilities where multipoint air monitoring systems will be 2 employed involve the use of air handling units that involve return air where a percentage of 3 the air returned to the air handling unit is mixed with some percentage of outside air to 4 provide supply air to various rooms or spaces within a building.
Alternatively, the building may in some cases contain critical environments such as laboratories or vivariums which are 6 one pass environments that do not use return air and instead exhaust all the air supplied into 7 the critical environment rooms. Although many of the figures of this patent are directed to a 8 building with return air, the invention can also be used for one pass critical environments as 9 well.
For multipoint air monitoring systems where remote sensors are used, air is 16 transported through a tube or pipe for sampling or measurement purposes.
For example, a 17 multipoint air monitoring system may have one or more centrally located air quality 18 parameter sensors instead of distributed sensors local to the sensed environment. As such, i9 this centralized air quality parameter sensor may be used in these systems to sense several or a large number of locations. These centralized air monitoring systems are also referred to in 21 the context of this invention as multipoint air sampling systems, or as multiplexed or shared 22 sensor based facility monitoring systems.
23 Multipoint air sampling system are defined for the purposes of this invention as 24 specifically a facility monitoring system that uses shared or multiplexed sensor(s) consisting of either a single remote sensor or a set of remotely located sensors that is used to monitor a 26 plurality of spaces, areas or rooms within a building, or outside adjacent to a facility by 27 transporting samples or packets of air from the spaces to be monitored to the at least one air 28 quality parameter sensor.
29 For one class of these multipoint air sampling systems specifically defined, in the context of this invention, as star configured multipoint air sampling systems or just star 31 configured systems, multiple tubes may be used to bring air samples from multiple locations 32 to a centralized sensor(s). Centrally located air switches and/or solenoid valves may be used 33 in this approach to sequentially switch the air from these locations through the different tubes 34 to the sensor to measure the air from the multiple remote locations. Each location may be 1 sensed for between 10 seconds or several minutes. Depending on how many locations are 2 sensed each space may be sensed on a periodic basis that could range from 5 to 60 minutes.
3 These star configured systems are sometimes called octopus-like systems or home run 4 systems and may use considerable amounts of tubing.
Systems such as this, for example, have been used to provide monitoring functions for 6 the detection of refrigerant leaks, and other toxic gas monitoring applications. Other systems 7 similar to this, such as that described within U.S. Patent No. 6,241,950 to Veelenturf et al., 8 discloses a fluid sampling system including a 9 manifold having inputs, common purge and sampling pathways, and valves to 1o couple/decouple first and second sets of inputs for measuring pressure differentials across 11 sample locations.
12 Additionally, these types of star configured systems have been used to monitor 13 particulates in multiple areas such as clean room areas with a single particle counter. A prior 14 art example of this is a multiplexed particle counter such as the Universal Manifold System and Controller as made by Lighthouse Worldwide Solutions, Inc. coupled with one of their 16 particle counters such as their model number Solair 3100 portable laser based particle counter 17 or an obscuration based particle sensor, 18 Regarding absolute moisture or dewpoint temperature measurement an example of a 19 prior art star configured multipoint air sampling system that can be used to measure dewpoint temperature is the AIRxpert 7000 Multi-sensor, Multipoint Monitoring system manufactured 21 by AlRxpert Systems of Lexington, Massachusetts, www.airexpert.com.
22 Another multipoint air sampling system defined in the context of this invention as a 23 networked air sampling system uses a central "backbone" tube with branches extending to 24 various locations forming a bus-configured or tree like approach similar to the configuration of a data network. Air solenoids are typically remotely located proximate to the multiple 26 sampling locations. The sampling time for each location like with the star configured 27 systems may vary from about 10 seconds to as much as several minutes. A
typical sampling 28 time per location would be about 30 seconds, so that with 30 locations sampled, each location 29 could be sampled every 15 minutes. Networked air sampling systems can potentially be used to sample locations within a building, an air handling unit ductwork, exhaust air stacks of a 31 building, or outside a building. An exemplary networked air sampling system is described in 32 U.S. Patent No. 6,125,710 to Sharp.
33 U.S. Patent No. 7.302.313 to Sharp et. al., titled "Air Quality Monitoring Systems and 34 Methods", references different multipoint air monitoring systems including multipoint air 1 sampling systems as used with expert system analysis capabilities and is also incorporated 2 herein by reference.
3 Finally another multiplexed form of facility monitoring system that may be used to 4 implement portions of this invention is defined in the context of this invention as a networked photonic sampling system that multiplexes packets of light vs. packets of air and may 6 incorporate either a star configured or network/bus type of layout. The basic concept uses a 7 central laser emitter and a central laser detector that sends out and detects laser light packets 8 that are switched into rooms to be sensed by optical switches. Optical fiber sensors, infrared 9 absorption cells or sensors, and other sensing techniques are located and used in the sensed area to change the properties of the light due to the affect of the environment. The light 11 packet is then switched back to the central detector where the effect of the environment on 12 the light properties is determined. A major benefit of the system is that the sensors such as 13 the fiber or open cell sensors are potentially quite low in cost. The expensive part is the laser 14 and detector systems that are centralized. Similar to the previous multipoint air sampling systems, multiple affects on the light from particles, gases and other contaminants, humidity, 16 etc. can be done simultaneously with central equipment and the telecom concept of 17 Wavelength Division Multiplexing which allows multiple wavelengths and hence multiple 18 signals to share the same fiber. A clear advantage of this system is the ability to have a very 19 rapid cycle time that can be in the ten's of milliseconds or less. This sampling system is detailed in U.S. Patent No. 6,252,689, entitled "Networked Photonic Distribution System for 21 Sensing Ambient Conditions".
22 The multipoint air sampling systems and networked photonic sampling system which 23 have been described heretofore and are collectively referred to as sampling systems may be 24 applied to monitor a wide range of locations throughout a building, including any kinds of rooms, hallways, lobbies, interstitial spaces, penthouses, outdoor locations, and any number 26 of locations within ductwork, plenums, and air handlers. To provide control as well as 27 monitoring of these different spaces, virtual sensor signals can be created that in the context 28 of this invention refer to software or firmware variables, or continuous analog or digital 29 signals that can be passed to other systems such as a building control or laboratory airflow control system and are representative of the state of a given space's air quality parameter 31 value. In effect these signals are reflective of what a local sensor would read if it was being 32 used instead of the multipoint air sampling system or networked photonic sampling system 33 otherwise known collectively again as sampling systems.
1 Multipoint air sampling systems have been used with a wide variety of air quality 2 parameter sensors to monitor a wide variety of air quality attributes or air characteristics of a 3 building or facility. In the context of this invention an air quality parameter sensor is a sensor 4 that can detect one or more air quality attributes or parameters that convert the level of or information about the presence of an air quality parameter into either a continuously varying 6 or else discontinuous pneumatic, electronic, analog or digital signal or else into a software or 7 firmware variable representing the level of or information about the presence of an air quality 8 parameter in a given space. The air quality parameter sensor may be based on any of a 9 variety of sensing technologies known to those skilled in the art such as for example electrochemical, photonic or optical, infrared absorption, photo-acoustic, polymer, variable 11 conductivity, flame ionization, photo-ionization, solid state, mixed metal oxide, ion mobility, 12 surface acoustic wave, or fiber optic. The air quality parameter sensor may be a wired or 13 wireless sensor type and be implemented with various types of physical hardware such as for 14 example micro-electro-mechanical system based (MEMS), nanotechnology based, micro-system based, analog based, or digital based. Additionally, an air quality parameter sensor 16 may sense for more than one air quality parameter, and may include more than one air quality 17 parameter sensor in a single packaged device.
18 Furthermore, for the purposes of this patent an air quality parameter is defined as an 19 air characteristic that can consist of an air contaminant, an air comfort parameter, or carbon dioxide (C02). An air contaminant in the context of this patent refers to certain potentially 21 harmful or irritating chemical, biological, or radiological composition elements or properties 22 of the air such as for example CO, particles of various sizes, smoke, aerosols, TVOC's (Total 23 Volatile Organic Compounds), specific VOC's of interest, formaldehyde, NO, NOX, SOX, 24 SO2, hydrogen sulfide, chlorine, nitrous oxide, methane, hydrocarbons, ammonia, refrigerant gases, radon, ozone, radiation, biological and or chemical terrorist agents, other toxic gases, 26 mold, other biologicals, and other contaminants of interest to be sensed.
An air contaminant 27 specifically does not refer to such other air quality parameters such as temperature, carbon 28 dioxide, or any one of the many forms of measuring moisture or humidity in air such as for 29 example relative humidity, dewpoint temperature, absolute humidity, wet bulb temperature, enthalpy, etc.
31 Furthermore, air contaminants can be further subdivided into two categories, gas 32 based contaminants and particle based contaminants. Gas based contaminants are defined in 33 the context of this invention as air contaminants that are gas or vapor based such as CO, 34 TVOC's, ozone, etc. Particle based contaminants on the other hand consist of viable and 1 nonviable air borne particulate matter of any size, but generally of a particle size from .01 2 microns up to 100 microns in diameter. As such this category of contaminants also includes 3 all biological particulate matter such as mold spores, bacteria, viruses, etc.
4 Carbon dioxide refers specifically to the gas carbon dioxide that is found naturally in the atmosphere as a component constituent in addition to oxygen and nitrogen.
It is typically 6 found in outside air at concentrations between 300 and 500 PPM and is exhaled by human 7 beings at an approximate rate of .01 CFM per person for a person doing typical office work.
8 Variations in the number of people in an office compared to the amount of outside air 9 supplied into the building can easily vary indoor CO2 levels to between 500 and 2500 PPM.
As such CO2 can be used as an excellent indicator of proper ventilation on a per person basis 11 sometimes referred to as the CFM of outside air per person since the level of CO2 in a space 12 is directly related to the number of people in a space divided by the rise in CO2 from outdoor 13 levels. Although high CO2 levels are often associated with poor indoor air quality levels, it is 14 not the level of CO2 itself that creates the discomfort and symptoms associated with poor indoor air quality but instead the associated rise in air contaminants that are not being 16 properly diluted. Human beings are unaffected by relatively high levels of CO2 such as up to 17 5000 PPM, which would be extremely rare to find in any building of ordinary construction.
18 For the purposes of this patent an air comfort parameter specifically refers to either 19 the measurement of temperature or one of the many related psychrometric measurements of moisture or humidity in air such as again, relative humidity, dewpoint temperature, absolute 21 humidity, wet bulb temperature, and enthalpy. An air comfort parameter also does not refer 22 to either carbon dioxide or any air contaminants. Additionally, in the context of this 23 invention, an air quality parameter, air contaminant, or air comfort parameter specifically do 24 not include any measure of airflow volume, velocity or pressure such as for example measurements of air volume that may be indicated in units of cubic feet per minute of air or 26 other units, velocity pressure, air speed or velocity, static pressure, differential pressure, or 27 absolute pressure.
28 In the past, prior art multipoint air sampling systems have been used from time to time 29 to provide monitoring, data logging, alarming, control, or limit functions for one or more individually sensed air quality parameters but not for blended or composite air quality 31 parameter signals.
32 In the context of this invention, a blended air quality parameter signal, also referred to 33 as a composite air quality parameter signal, is defined as an analog signal, digital signal, 34 optical signal, software or firmware variable or address location or other time based 1 representation of information that is affected by, related to, or in some manner a function of a 2 plurality of air quality parameters relating to one or more locations such as rooms, spaces, 3 areas, air ducts, or critical environments within a building or the ambient conditions 4 surrounding or adjacent to a building or facility. Such a blended or composite air quality parameter signal can be used to realize benefits such as simplicity, accuracy, cost 6 effectiveness, and reliability compared to prior art approaches. The blended signals can also 7 uniquely enabling new air flow control applications as described later, as well as be used for 8 general IEQ monitoring, commanding airflow control devices, or used in the control of any 9 aspect of a building's operation to which they are pertinent such in conjunction with its HVAC and building controls system.
11 Concerning other aspects of the prior art, the alarm or limit function output signals for 12 individual air quality parameters from multipoint air sampling systems have in the past 13 sometimes been communicated to other systems, such as a building management system 14 (BMS) which, based on the state of these functions, can affect aspects of the operation of a building, such as for example the air flow rate to a location within a zone monitored by the 16 multipoint air sampling system in which the monitoring system has detected that an 17 individually sensed air quality parameter has exceeded a predetermined limit. For example, 18 sampling based refrigerant monitoring systems are examples of multipoint air sampling 19 systems that provide alarm/limit functions such as this for individual parameters in which one or more relay contacts or analog output signals (such as 0-l Ovolt or 4-20 milliamp signals) 21 are provided either locally where the shared sensor or sensors reside or via remote modules 22 that are in communication with the sensor hardware via a digital network.
23 multipoint refrigerant monitor by the Vulcain division of BW Technologies, is an example of 24 a monitoring system with capabilities such as this. In this way, multipoint air sampling systems have been used to provide a discontinuous signal, typically via a relay contact, which 26 in turn provides a discontinuous control function based on a single air quality parameter.
27 Note that in the context of this patent a discontinuous signal is defined as one with a limited 28 set of values or states such as two or three states and steps between the values with no 29 intermediate values or states. A discontinuous control function in the context of this patent is similarly defined as one with a limited set of output values or states such as two or three and 31 similarly steps between these values with no intermediate values or states.
32 U.S. Patent numbers 5,292,280 and 5,267,897 describe another multipoint air 33 sampling system that monitors a single trace gas, typically carbon dioxide (C02), at multiple 34 locations, including return air, outside air, and the supply discharge air associated with an air 1 handler in order to directly compute the outside air flow component for purposes of 2 controlling the air handler. This method uses a common C02 or trace gas sensor and valves 3 assigned to each of the sampled locations to provide a multiplexed signal from the C02 4 sensor that varies in time based on the current location being sampled. The time variant signal from the shared C02 sensor is read by a separate control module, where it is 6 decomposed into three separate C02 or trace gas signals, based on continuous knowledge of 7 the sequence state, representing outside air, return air, and supply discharge air C02 8 concentrations.
9 A similar multipoint air sampling system prior art method described by Warden in a 1o paper entitled "Supply air C02 Control of minimum outside air for multiple space systems", 11 David Warden, published in October of 2004 in the ASHRAE Journal applies a common 12 single parameter C02 sensor, using a three-way valve or two separate two-way valves to 13 alternately switch air samples taken from an air handler's supply discharge air as well as that 14 from outdoors. This creates a multiplexed signal that can be decomposed by a computer in the form potentially of a Direct Digital Control module (or DDC controller) in order to get a 16 reading of supply air CO2 concentration with respect to outside air C02 concentration that in 17 turn can be used to control the outside air intake to the air handler.
18 U.S. Patent No. 6,609,967 and 6,790,136 to Sharp and Desrochers discloses methods 19 and apparatus to safely re-circulate air in a controlled ventilated environment for minimizing ventilation and thermal load requirements for each room, and thereby reducing the amount of 21 required outside air. In particular, if one or more individual air contaminants are sensed in 22 one of the rooms of the ventilated environment, the amount of air re-circulated from that 23 room is reduced or potentially shut off to prevent contaminating other rooms in the ventilated 24 environment.
Other prior art systems such as the AlRxpert 7000 Multi-sensor, Multipoint 26 Monitoring system mentioned above or the networked air sampling system previously 27 mentioned in U.S. Patent No. 6,125,710 to Sharp discuss measuring multiple individual air 28 quality parameters but again do not discuss how to create or employ a blended air quality 29 parameter signal from these systems.
Additionally, heretofore the use of multiple individual local sensors to create 31 composite signals from multiple locations would have involved a large number of individual 32 sensors used with a building management system (BMS) or data acquisition system with an 33 associated large first cost and large ongoing calibration costs. Multipoint air sampling 34 systems on the other hand can sense multiple parameters cost effectively on a discrete 1 sampled and individual basis, although as mentioned above, means has been lacking 2 heretofore to properly combine and blend this information on a discontinuous or continuous 3 basis so it can be beneficially applied to appropriate monitoring or control applications.
4 One pertinent application where blended air quality parameter information can be used to significant advantage involves room or area based demand control ventilation (DCV) 6 as applied for example to an office, classroom, assembly, auditorium or variable occupancy 7 space or air handling unit based demand control ventilation as applied to air handler of a 8 building. As described in the previously mentioned paper by Warden entitled "Supply air 9 C02 Control of minimum outside air for multiple space systems", the outside air into a facility as well as the amount of supply air into a given room or area can be varied based on 11 the amount of people in the facility or the given area or room by measuring a proxy 12 measurement for occupancy and ventilation which is C02. As described previously, the 13 more people in the space or building the more C02 rises allowing a measurement of C02 to 14 drive and increase outside air into the building when the number of people increases or conversely allows the amount of outside air to drop when less people are in the space.
16 Similarly for room or area based demand control ventilation when the C02 level of an area 17 rises, the supply air into the space can be increased to increase the amount of dilution 18 ventilation in that space and conversely when C02 levels drop due to a reduction in people in 19 the space such as a conference room, the supply air into the space can be decreased down to the minimum supply air required to handle the room's thermal load to save energy.
21 Although these two demand control ventilation approaches of room based dilution 22 ventilation control and air handler based outside air control has been used for some number 23 of years, a problem with these concepts is the potential presence of non-human pollutants 24 such as particles, carbon monoxide, TVOC's (Total Volatile Organic Compounds) or other air contaminants that can accumulate and rise in value when a source of them is present and 26 ventilation levels are low. If for example a space is sparsely populated, and some strong and 27 potentially irritating cleaning compounds are used in the space, problems could ensue for 28 those existing occupants since the low level of occupants would have driven the ventilation 29 rates down to a low level when in reality the presence of the cleaning compounds should 3o necessitate a much higher ventilation rate. As mentioned in an ASHRAE
Journal article 31 dated July of 2003 titled "Demand Control Ventilation" by authors, Kurt W.
Roth, John 32 Dieckmann, and James Brodrick that although "In practice DCV has reduced annual energy 33 costs by $0.05 to $1 per square foot..... Currently, most buildings do not use DCV because of 34 concerns about nonhuman indoor pollutants mentioned previously."
1 In addition to the previously high cost of sensing these non human indoor pollutants 2 or air quality parameters it has also not been known to those skilled in the art of ventilation 3 control how very different air contaminants such as TVOC's, particles, carbon monoxide and 4 others should be used in conjunction with carbon dioxide information, which is itself not a contaminant, to properly control the outside air into the building through blending the 6 elements of both demand control ventilation using CO2 plus dilution ventilation control 7 based on one or more air contaminants.
8 Referring to another industry problem, although there are many advantages to solely 9 using a multipoint air sampling systems as described above to create a composite or blended 1o air quality parameter signal, there are certain air quality attributes that can not be properly 11 detected with the use of at least some if not all of these multipoint air sampling systems.
12 Most notably, temperature can not be sensed remotely with a centralized sensor since the 13 temperature of the air sample pulled through the air sampling conduit or tube will rapidly 14 change temperature to equal the temperature of the sampling conduit or tube. In many cases the air does not need to travel more than 10 to 20 feet before its temperature has been 16 substantially affected by the temperature of the sampling tubing.
Furthermore, there are also 17 other air quality attributes such as ozone or particles that depending on the type of tubing 18 used or the speed of transport, may be affected by transport through the tubing.
19 With respect to temperature, for example, the inability of a remote sensor based multipoint air sampling system to measure the room or duct temperature at air sampling locations creates a 21 problem in measuring such moisture related properties as relative humidity and enthalpy 22 using a multipoint air sampling system. This is because only the absolute humidity, the 23 amount of water vapor in the air in parts per thousand or the dewpoint temperature can be 24 measured directly by a multipoint air sampling system. Thus, the difficulty in obtaining a measurement of the air sample's temperature before it is affected by the air sampling tubing 26 and then combining or blending that temperature measurement with the absolute humidity 27 measurement has in the past prevented the use of these multipoint air sampling systems for 28 the monitoring or control in rooms or in air ducts of the blended air quality parameters of 29 relative humidity and enthalpy.
This is potentially important since local relative humidity and enthalpy sensors, 31 potentially used in the economizer of an air handling unit, are difficult to maintain and keep 32 accurate when used as local sensors particularly for certain applications involving the 33 measurement of outside air due to the wide ranging temperature of this air and it's typically 34 heavy concentration of particulates and dust. For example, a recent study by the New 1 Buildings Institute of economizers and air handling units in the Pacific Northwest stated that 2 approximately two thirds of the economizers evaluated were not working properly or had 3 failed completely in many cases due to the failure of the sensors.
4 To explain this application in more detail, an economizer as defined in the context of this patent is a system that exists as a part of a building air handling system for reducing 6 cooling costs by introducing outside air in lieu of, or to assist with, mechanical cooling such 7 as mechanical equipment based air conditioning. The effectiveness of an economizer is 8 largely based on its ability to sense when outside air conditions are suitable so that the outside 9 air can be used for so-called "free cooling" to reduce compressor use. U.S.
4,182,180 and 4,570,448 disclose exemplary 11 techniques for using outside air for cooling. This includes dry-bulb temperature, single 12 enthalpy, and differential enthalpy based economizers. Of these types of economizers, 13 enthalpy based types (particularly differential enthalpy based economizers) have 14 demonstrated better performance, especially in hotter more humid climates, where the latent heat load associated with cooling outside air can be a significant factor. For this application, 16 enthalpy sensors are available for use with economizers such as Honeywell Part No. C7650, 17 solid state economizer control.
18 Although the savings potential with enthalpy based economizers can be significant, 19 these systems as mentioned above, often realize limited savings in practice due in part to issues with unreliable sensor technology, as is well known in the art. ASHRAE
(American 21 Society of Heating, Refrigerating and Air-Conditioning Engineers) has commented on the 22 limited reliability of these sensors such as in the ASHRAE Standard 90.1 Users Manual.
23 Known enthalpy sensors were based on a plastic filament that could deteriorate over time 24 leading to failure or gross calibration errors. Newer sensors are based on solid-state designs, but they are still subject to drift and repeatability problems.
26 Centralized remote absolute humidity and chilled minor hygrometers are much more 27 accurate, reliable and are cost effectively used when as part of multipoint air sampling 28 system. If the aspect of local temperature measurement could be cost effectively solved then 29 these sensors could be advantageously used for the more commonly used measurements of relative humidity and enthalpy.
31 Another problem with economizers is that there are times when outdoor conditions 32 are worse than indoor conditions such as with a building located near a major highway during 33 rush hours. During these periods if the economizer is calling for free cooling, potentially 34 100% outside air is being drawn into the building which may be saving energy, but due to the 1 high traffic outside the building the indoor air quality of the facility may actually be made 2 worse. As a result it would be helpful to be able to create a blended outdoor air contaminants 3 signal incorporating multiple air contaminants such as TVOC's, CO, and potentially particles 4 that could be used with the air handler to override the economizer's control of outside air when the outside air is "dirty".
6 One known problem with dilution ventilation in buildings using air contaminant 7 sensors such as for example sensors for particles, CO, TVOC's or other air contaminants is 8 that if the outside air concentrations becomes high enough, increasing the airflow volume of 9 outside air or the supply air into a controlled area or room will actually increase the sensed air contaminant levels in a space, duct or air handler. This can potentially create a negative 11 feedback situation when the inside dilution ventilation threshold levels are exceeded forcing 12 the outside airflow levels and or room supply air flow levels to their maximum level.
13 Depending on the level of design capacity of the HVAC system, the capacity of the air 14 handling system could be exceeded in this latch-up situation, causing a degradation of HVAC
17 It is therefore a primary object of this invention to provide a system for providing 18 blended air quality parameter measurements derived from individual air quality parameter 19 measurements using at least in part a multipoint air sampling system and in some cases also local discrete air quality parameter sensors.
21 It is a further object of this invention to provide a system for providing air quality 22 parameter measurements of improved accuracy and cost effectiveness that cannot be 23 achievable with the use of either only discrete local sensors or the use of only a multipoint air 24 sampling system.
It is also an object of this invention to provide systems and methods for providing cost 26 effective and accurate blended air quality parameter sensor measurements of a type not 27 available commonly in the past for the purposes of controlling building HVAC (Heating, 28 Ventilating, and Air Conditioning) operations and equipment including controls equipment.
29 It is another object of this invention is to enable specific control and monitoring applications involving the creation of blended air quality parameter measurements of relative humidity 31 and or enthalpy that can be done more cost effectively and accurately with the use of the 32 invention.
33 It is also an object of this invention to enable an improved and more healthy form of 34 demand control ventilation involving the creation and use of an improved outside air control 1 signal and or a supply airflow control signal. These control signals are also known as outside 2 air command signals and or dilution ventilation command signals can for example be created 3 using a blended air quality parameter signal that may typically incorporate aspects of carbon 4 dioxide level information to implement aspects of demand control ventilation as well as information from at least one other air quality parameter measurement such as TVOC's, 6 particles, carbon monoxide, or even humidity to assist in maintaining good air quality in a 7 space or a building by providing adequate levels of supply airflow to a space and or outside 8 airflow into a building to dilute any such sensed air contaminants down to safe or 9 recommended levels.
The latter embodiment of the current invention is implemented using the virtual 11 signals from a multipoint air sampling system and or the signals from local room or duct air 12 quality parameter sensors and combines them via one or more of multiple approaches using a 13 signal processing controller or other means such as a building control system to create a 14 dilution ventilation command signal and or an outside airflow command signal. In the context of this invention a dilution ventilation command signal is defined as an airflow command 16 signal that can be used to vary, at least partially the supply airflow rate into a monitored room 17 or space based on sensed air quality parameter information. The purpose of this control signal 18 is to appropriately increase ventilation when air contaminant levels in a space or building are 19 too high, typically to improve indoor air quality, and to decrease airflow levels, typically to save energy, when both the number of occupants in a space is reduced and the air is relatively 21 clean of contaminants.
22 In the context of this invention an outside airflow command signal is defined as an 23 airflow command signal that can be used to vary, at least partially the outside airflow into a 24 building or air handling unit based on potentially multiple factors. These factors include for example the sensed air quality parameter information inside the building, the sensed air 26 quality parameter information outside the building, the comparative levels of inside and 27 outside sensed air quality parameters, the amount of free cooling to optimize energy 28 efficiency and comfort, and the amount of outside airflow required to meet recommended 29 guidelines based on the real time or design occupancy of for example the entire area of the 3o building served by a particular air handling unit, specific critical areas served by the air 31 handling unit, or areas served by the air handling unit with varying occupancy. The purpose 32 of this control signal is to balance energy savings from free cooling and demand control 33 ventilation with providing enhanced indoor air quality through increased dilution of internal 1 contaminants and preventing the excessive use of outside air when it is "dirty" or has 2 excessive levels of air contaminants.
3 For the purposes of this patent, an airflow command signal is any pneumatic, 4 electronic, analog or digital signal, or a software of firmware variable that operates in a firmware or software program running on a microprocessor or computer; and that is used by 6 the room airflow controller, the outside airflow controller, the building control system, by one 7 of the return, exhaust, or supply airflow control devices located in a room or space within the 8 building, or by an outside airflow, recirculated airflow, or building exhaust airflow control 9 device or damper often associated with a building's air handling unit or HVAC system.
1o These command signals serve to at least partially vary or control one or more of the aspects 11 of or relationships between any one of the airflows moving into or exiting the building, an air 12 handler or an area, space, room or environment within the building. If the airflow command 13 signal is of a continuously varying nature it can be referred to herein as a VAV or variable air 14 volume command signal. Otherwise, the airflow command signal may be a discontinuous airflow command signal which in the context of this invention is defined as a signal that may 16 have only two levels or states and for the purposes of this patent is referred to as a two state 17 signal, or it may have three levels or states and may thus be referred to in the context of this 18 invention as a three state signal. Alternatively, the discontinuous airflow command signal 19 may have multiple discrete levels or states and as thus may be referred to herein as a multiple state signal.
21 For the purposes of this invention a signal processing controller as mentioned above 22 refers to analog or digital electronic circuitry, and or a microprocessor or computer running a 23 software or firmware program that uses at least information, signals and or software or 24 firmware variables from either individual local sensors of air quality parameters plus virtual sensor signals, information and or software or firmware variables from remote or centralized 26 sensors of air quality parameters, and blends, combines or processes this information in a 27 potential multitude of ways. As a result the signal processing controller either creates airflow 28 command signals for building outside airflow control, for dilution ventilation, offset air 29 volumes, or other airflow commands to be used by a room airflow controller, and or for creating signals or information that can be used by other control devices such as a building 31 control system for at least partially controlling building level airflows including outside 32 airflow into the building as well as one or more room airflows of supply, return, exhaust or 33 offset airflow, and or is used for some other control or monitoring function that is in some 34 way related to the control of one of the aforementioned room or building airflows.
1 In the context of this invention, a building control system or building management 2 system as mentioned above is defined as a control system located in a building or facility that 3 is used to control one or more functions of the HVAC system in a building such as for 4 example control of space temperature, space relative humidity, air handling unit airflows and operation, exhaust fan flows, chiller operation, economizer operation, duct static pressures, 6 building pressurization, and critical environment airflows. These systems often integrate 7 with or incorporate other building systems or subsystems such as fire and security, card 8 access, closed circuit TV monitoring, smoke control systems, power monitoring, tracking 9 airflow control systems, and critical environment airflow control systems.
Building control 1o systems may have pneumatic, electric, electronic, microprocessor, computer, or web based 11 controls using pneumatic, analog and or digital signal inputs and outputs.
These systems 12 often have centralized monitoring functions, centralized or local control capabilities, and may 13 have Internet or web based access. They may also be referred to as building management 14 systems (BMS), facility control systems (FCS), or facility management systems (FMS).
It is another object of this invention to provide systems and methods for preventing 16 dilution ventilation and outside airflow control from becoming latched up at high flow rates 17 due to high outdoor levels of air contaminants. A preferred embodiment to solve this issue 18 for outdoor air control involves using blended air contaminant signals for control that are 1g created from taking the differential of indoor to outdoor contaminant levels vs. the absolute indoor levels. The use of a multipoint air sampling system provides uniquely high accuracy 21 to make this application possible since both indoor and outdoor measurements are made with 22 the same sensor substantially reducing normal sensor errors that would typically be magnified 23 when taking the difference between two different sensors. Likewise a preferred embodiment 24 to solve this issue for room based dilution ventilation control involves using blended air contaminant signals for control that are created using a shared sensor air sampling system that 26 generates a differential air contaminants signal using the difference between the 27 measurements of area or space contaminant levels compared to the levels of contaminants in 28 the supply air feeding the monitored area or space.
29 Lastly, when multiple air quality parameters are to be used by a signal processing controller to help create a dilution ventilation or outside airflow command signal, particularly 31 where each air quality parameter has a different threshold of concern, each air quality 32 parameter can be scaled to a standard scale relative to that threshold. For example 2 volts in 33 a 0 to 10 volt scale can represent the threshold at which point the airflow should begin to be 34 increased with 10 volts representing maximum flow. The individual signals can then be 1 either high selected so the higher of these signals controls the dilution flow. Alternatively, 2 the signals can be summed together after they have been weighted in a relative manner based 3 on the severity of the health effects of each sensed compound or the previous threshold based 4 weighting. Non linear weighting may also be used where for example the increased level of a dangerous contaminant over a threshold calls for much higher airflows such as for carbon 6 monoxide versus a more benign but still important contaminant such as particles.
8 Other objects, features and advantages will occur to those skilled in the art from the 9 following description of the preferred embodiments and the accompanying drawings in 1o which:
11 FIG. 1 is a schematic diagram of a preferred embodiment of the system of the 12 invention in which a plurality of spaces and air ducts are being monitored by a multipoint star 13 configured air sampling system.
14 FIG. 2 is a schematic diagram of a preferred embodiment of the system of the invention in which a plurality of spaces and air ducts are being monitored by a multipoint 16 networked air sampling system.
17 FIG. 3 is a detailed schematic diagram of a preferred embodiment of the system of the 18 invention in a room.
19 FIG. 4 is a schematic diagram of a portion of a preferred embodiment of the signal processing logic of the invention that may be used to create the dilution ventilation command 21 signals.
22 FIG. 5 is a schematic diagram of an embodiment of the room airflow controls logic of 23 the invention for a space including a controlled room return airflow control device.
24 FIG. 6 is a schematic diagram of a preferred embodiment of the system of the invention in which a building air handling unit incorporating return air is being monitored by 26 a multipoint air sampling system.
27 FIG. 7A and 7B are schematic diagrams of various steady-state levels associated with 28 air change rate control sequences.
29 FIGS. 8A and 8B are diagrammed strategies for controlling the air change rate in a space or building environment using a closed loop system to provide dilution ventilation or 31 outside air control by varying the supply air flow rate within the environment or the outside 32 air into the building.
1 FIG. 9 is a schematic diagram of a portion of a preferred embodiment of the outside 2 airflow controller logic of the invention that may be used to create the outside airflow 3 command signals.
6 FIG. 1 and 2 show a typical set of monitored environments or rooms 20A, 20B, and 7 20C that have doors entering a corridor 10 that is also being monitored.
Although the 8 diagrams show three rooms and a corridor, the present invention may be used with just one 9 room or space or monitored area or any plurality of rooms or spaces including corridors or other adjacent spaces that are also being monitored, such as for example, two or more rooms, 11 or one corridor plus one or more spaces. Note also that, although the environments shown in 12 the Figures are enclosed within walls, monitored environments, spaces or areas in the context 13 of this invention may also be a section or area of a room having no walls or partitions around 14 it. Thus, there may be multiple monitored environments within one physical room.
Alternatively, multiple physical rooms may also constitute one environment or space.
16 Typically, the environment 20 will also be an area that is fed by one or more supply airflow 17 control devices 51. Potentially a return airflow device 41A maybe used that is controlled by 18 room airflow controller 30 or there may be no controlled return air flow devices such as in 19 rooms 20B and C. In the latter two cases the supply air may make its way back to the air handler via transfer ducts 40B or ceiling grill 42C into a plenum space that is typically in a 21 ceiling space that eventually connects to the return airflow inlet of an air handling unit such 22 as air handler unit 1000 in FIG. 6 that is providing the supply air into or near the space. For 23 the purposes of this invention a room airflow controller such as room airflow controller 30 is 24 an airflow control apparatus that may be of analog or digital electronic design or may be constructed using a microprocessor or computer running a software or firmware program that 26 creates the airflow command signals for one or more supply and or return airflow control 27 devices possibly using information, signals and airflow commands from other devices, 28 systems or controllers.
29 These sets of rooms in FIG. 1 and 2 are further described as having a source of supply 3o air from supply air ducts 50A, 50B, and 50C, originating from air handler unit 1000 in FIG.
31 6, that may exit the room as return air through a plenum space or from controlled return duct 32 40 A, uncontrolled return duct 40B, or plenum space 40C. Although not shown in the 33 figures, the corridor 10 often has a source of supply air as well. The supply ducts 50A, B and 34 C also contain airflow control devices 51A, B, and C. which supply air into the room or space 1 through supply flow grill or diffuser 52A, B, and C respectively.
Additionally, the room 2 return duct 40A contains return airflow control devices 41A which controls the amount of 3 room or space air pulled into the return duct. Return duct 40A, return transfer duct 40B, and 4 plenum space 40C connect to the rooms 20A, B, and C through a room return grill or vent opening 42A, B, and C respectively.
6 FIG. 1 and 2 also show the presence of an outside air intake 62 into the building 7 through outside air duct 60. This duct could be connected to or part of some type of an air 8 handling unit, such as the air handling unit 1000 in Fig. 6, to pull in outside air into the 9 building, it may be a source of dedicated outside or make up air into the building not associated with air handler unit 1000, or it may be an outside air pickup location specifically 11 used for or shared by the air sampling systems 100 and 200 of FIG. 1 and 2 respectively. An 12 outside airflow control device 67 is also shown as a means to vary and control the amount of 13 outside air entering the building.
14 An airflow control device as used in the context of this invention, such as supply, return, and outside airflow control devices 51A, 41A, and 67 respectively are defined as any 16 device known to those skilled in the art of airflow control for controlling air flow volume and 17 velocity through a duct or opening. For example, they can be constant volume, two state, 18 multiple state, or variable air volume (VAV) boxes or terminals such as manufactured by 19 Titus, Metal Aire, Enviro-Tec, or others. These devices use a damper or throttling device of some type such as a single round, square, or rectangular blade damper, a multiple blade 21 damper, a set of pneumatic bladders that can be used to seal off an opening, or any other type 22 of throttling device that can be used to seal off a duct, that is connected to a pneumatic, 23 electric, or electronic actuator that is controlled by a pneumatic, electronic, digital, or 24 microprocessor based controller which typically also relies on feedback of flow from a flow sensor for closed loop control of the duct's air volume. These flow sensors can be of various 26 types known to those skilled in the art, such as those based on single or multiple velocity 27 pressure sensors, hot wire, heated thermistor, microelectronic flow sensor, etc.
28 Alternatively, another type of flow control device that is commonly used is an airflow 29 control valve that typically has a venturi shaped body with a spring loaded cone that moves through the venturi shaped throat of the device to provide inherent, pressure independent 31 control of volume, such as manufactured by Phoenix Controls or others.
These valves 32 typically have pneumatic, electric, or electronic actuation to provide constant volume, two-33 state, multiple state, or variable air volume control. These devices often have large turndown 1 or flow ranges that make them very appropriate for control of dilution ventilation that can 2 have wide flow ranges to achieve optimum energy savings and safety.
3 Finally, another example of an airflow control device may simply be some form of a 4 single or multiple blade damper or other type of throttling device that is located either in an air handling unit, such as the dampers 1003, 1006, and 1067 in air handling unit 1000 in FIG.
6 6, an outside air duct, or a duct serving one or more areas. These throttling or damper devices 7 may or may not further be used with one of the airflow measuring devices aforementioned or 8 similar airflow measuring devices that are adapted using a grid of sensors or sensing holes for 9 example to measure the airflow accurately across a large cross sectional duct area. As an 1o example, outside airflow dampers providing airflow into an air handling unit are often not 11 used in conjunction with an airflow measuring device. Alternatively, other indirect means of 12 sensing the outside airflow may be used to provide better control of the outside airflow 13 control device.
14 With reference to FIG. 1, this diagram refers to a preferred embodiment of the present invention directed to control of rooms or areas using blended air quality parameter signals 16 from a star configured multipoint air sampling system 100. Multipoint air sampling system 17 100 could be a star configured multipoint air sampling system with a structure like that 18 described in U.S. Patent No. 6,241,950; U.S. Patent No. 5,292,280; U.S.
1g 5,293,771 or U.S. Patent No. 5,246,668. It could also be a refrigerant and toxic gas monitor adapted for this purpose such as the Vulcain Inc. multipoint sample draw gas monitor model 21 number VASQN8X as can be seen on their website at www.vulcainine.com or a multiplexed 22 particle counter such as the Universal Manifold System and Controller made by Lighthouse 23 Worldwide Solutions, Inc., as can be seen at their website at www.golighthouse.com, coupled 24 with one of their particle counters such as their model number Solair 3100 portable laser based particle counter or an obscuration based particle sensor. It could also be a star 26 configured multipoint air sampling system like that of the AlRxpert 7000 Multi-sensor, 27 Multipoint Monitoring system manufactured by AlRxpert Systems of Lexington, 28 Massachusetts, as can be seen at their website at www.airexpert.com.
29 In FIG. 1, a set of solenoid valves 161 through 167 is part of a multipoint air sampling system 100. Equivalently, these solenoids 161 through 167 could be replaced with other 31 switching means such as SSS-48C Single Scanivalve System manufactured by the Scanivalve 32 Corporation of Liberty Lake, Washington as can be seen on their website, 33 www.scanivalve.com, which uses a pneumatic selector switch and stepper motor to connect 34 one of many input ports to an outlet port which can be connected to a sensor such as a 1 pressure sensor. The solenoid valves 161 through 167 are controlled to switch in a sequence 2 by control logic 110. This sequence may be a simple sequential pattern of one solenoid after 3 another, or varied for example through programming to be one of potentially many preset 4 patterns, or it can have a pattern that can be interrupted and changed to a new sequence by manual or remote command or by a trigger event based on the values or signal pattern of one 6 or multiple sensed air quality parameters. This trigger event could be generated from outside 7 the multipoint air sampling system 100 or could be created from the sensor information 8 processed by signal processing controller block 130.
9 The solenoid valves 161 through 167 are connected to sampling locations 13, 23A, 1o and 23C in the spaces as well as duct sensing locations 43A, 43B, 53B, and 63 through tubing 11 14, 24A, 44A, 44B, 54B, 24C, and 64. In FIG. 1 for example, sampling location 13 in 12 corridor 10 is connected through tubing 14 to solenoid 161. Area sensing locations 23A and 13 C in rooms 20A and C are connected through tubing 24A and C to solenoids 162 and 166 14 respectively. Return duct sampling location 43A and return transfer duct sampling location 43B are connected through tubing 44A and B to solenoids 163 and 164 respectively. Supply 16 duct sampling location 53B is connected through tubing 54B to solenoid 165.
Finally outside 17 air duct sampling location 63 is connected through tubing 64 to solenoid 167. Alternatively, 18 tubing 64 may be connected to some other suitable location other than duct 60 to obtain 19 outside air samples.
The tubing mentioned above transports the air sample from the sensing location to the 21 solenoid of the multipoint air sampling system 100. The tubing typically will have an inner 22 diameter of one eighth to one half an inch in diameter with a preferred inner diameter of 23 about one quarter inches. This tubing can be made of standard plastic pneumatic tubing such 24 as Dekoron TM low density polyethylene (LDPE) plastic, Teflon, stainless steel, "Bev-A-Line XX " tubing made by Thermoplastic Processes, Inc. of Stirling, NJ, or other suitable 26 tubing materials known to those skilled in the art. For superior performance in transporting 27 both TVOC's and particles however, a material that is both inert to VOC's with very little 28 adsorption and desorption as well as electrically conductive to prevent static buildup is 29 preferred such as flexible stainless steel tubing. Other preferred materials and constructions 3o are described in U.S. Patent No. 7.216.556. filed on September 23, 2004 31 entitled, "TUBING FOR TRANSPORTING AIR SAMPLES IN AN AIR MONITORING
32 SYSTEM", as well as U.S. Patent No. 7.360.461 filed on June 10, 2005, 33 entitled, "AIR MONITORING SYSTEM HAVING TUBING WITH AN ELECTRICALLY
34 CONDUCTIVE INNER SURFACE FOR TRANSPORTING AIR SAMPLES".
1 Additionally in FIG. 1, a vacuum pump 140 pulls air from the sensing locations 2 through the tubing into the solenoids 161 through 167 and into a manifold 190 connecting all 3 the output ports of the solenoids together and to the inlet of the shared sensors 120. The 4 outlet of the shared sensors 120 is connected to the vacuum pump by tubing 141, whose construction is not critical and can be inexpensive plastic tubing such as the Dekoron TM
6 mentioned above or other. The inner diameter of this tubing can be made similar to the size 7 of the tubing connecting to the inlets of the solenoid valves or possibly larger for less 8 pressure drop. The shared sensors 120 can consist of one or more sensors to measure such air 9 comfort parameters as absolute humidity or dewpoint temperature, carbon dioxide, non-air quality parameters such as differential static pressure, or air contaminants such as for 11 example, CO, particles, smoke, TVOC's, specific VOC's of interest, formaldehyde, NO, 12 NOX, SOX, nitrous oxide, ammonia, refrigerant gases, radon, ozone, biological and or 13 chemical terrorist agents, mold, other biologicals, and other air contaminants of interest to be 14 sensed. These sensors may be connected in series, in parallel or a combination of both.
The signal outputs of the shared sensors 120 are passed to the signal processing 16 controller block 130 of the multipoint air sampling system 100. This block 130 also takes in 17 other sensor information from the sensor inputs block 150. This input block 150 accepts 18 sensor signals or information from local room or duct sensors if needed or desired rather than 19 remote sensors. For example, temperature cannot be sensed remotely, since the temperature of the air will change rapidly to the temperature of the tubing as it moves through the tubing.
21 Additionally, some areas may need instantaneous sensing of an air quality parameter. This is 22 shown in Room 20A where room sensor 25A, which could for example be a temperature 23 sensor, is connected to the sensor inputs block 150 through electrical cable 26A. If a 24 temperature sensor is used for 25A and is located near the sampling inlet 23A, then a shared sensor absolute humidity or dewpoint temperature measurement of that location can be 26 combined or blended with the temperature measurement from sensor 25A to create a very 27 accurate and cost effective measurement of relative humidity, enthalpy or one of the other 28 related psychrometric measurements. Likewise if outside air duct sensor 65 is used to 29 measure temperature than the combination of a shared sensor absolute humidity measurement or dewpoint temperature measurement from sampling location 63 which may be located close 31 to sensor location 65 will allow the calculation of an outside air measurement of relative 32 humidity, or enthalpy.
33 The sensors and the sensor inputs block may operate with many signal forms such as 34 analog voltage, analog current, or digital. Alternatively, the sensor may have its own onboard 1 microprocessor and communicate with the sensor inputs block 150 through a data 2 communications protocol such as, for example, LonTalk by Echelon Corporation, or an 3 appropriate protocol outlined by ASHRAE's BACnet communications standards, or virtually 4 any other appropriate protocol, including various proprietary protocols and other industry standard protocols commonly used to provide data communications between devices within a 6 building environment. Typically, however, when digital data communications are used to 7 connect to discrete devices such as 25A, this is accomplished using a protocol operating over 8 a physical layer such as an EIA485 physical layer, on top of which a suitable upper level 9 protocol will be used. In such cases, for example, cable 26A may be specified as a twisted shielded conductor pair. Nevertheless the connections between sensor 25A and input block 11 150 may be accomplished using any number of cable types common to the building controls 12 industry. Additionally, cable 26A may be omitted and the sensor 25A may communicate 13 wirelessly to inputs block 150 using such protocols and approaches as IEEE
802.11 a/b/g, 14 Zigbee, Bluetooth, mesh networking or other wireless methods used in the building and IT
(Information Technology) industry.
16 The signal processing controller block 130 is used to process the sensor information 17 from the shared sensors to create virtual sensor signals reflective of the environmental 18 conditions in the sensed locations. This information is added to the information from any 19 local room sensors such as 25A or duct sensor 65, and may be further processed to create blended or composite air quality parameter signals and is then used in a variety of possible 21 ways. For example, this information can be sent to building control system 180 for 22 monitoring and or control purposes through a digital networked connection 181. The 23 information interchange could be done using for example, a BACnet protocol, Lonworks, 24 OPC, XML data interchange or other suitable interface information conversion. The physical connection 181 could be an Ethernet connection, EIA485 (also known as RS485) connection 26 or other type of digital data communications connection. Another use of the data can be to 27 send it through an internal and or external local area or wide area network for monitoring at a 28 remote location. Additionally, the data can pass directly, or through a local area network, 29 phone network or other suitable connecting means 171 to connect to the Internet or a 3o dedicated network from which a website or other suitable means can be used to remotely 31 access, display, and analyze the data from the multipoint air sampling system 100.
32 Most importantly, signal processing controller block 130 can also provide the control 33 signals 31 used by the room airflow controller 30 which in FIG. 1 is shown as blocks 30A, B, 34 and C and dilution ventilation command signals 3 1A, B, and C. Control signal 31 is used to 1 dynamically vary the minimum supply airflow rate of the spaces which also equivalently 2 controls the amount of dilution ventilation for rooms 20A, 20B, and 20C.
Since one of the air 3 quality parameters that can be sensed by the shared sensors is carbon dioxide, a blended 4 dilution ventilation command signal can also include information relating to carbon dioxide levels in a given space to implement a local room level demand control ventilation approach 6 that responds to varying occupancy. Also, given the flexible nature of the electronics 7 associated with room airflow controller 30, part or all of the functions performed by signal 8 processing controller 130 may be performed within room airflow controller 30, which can be 9 a programmable device. In this case, signal 31 may at least in part be created within controller 30.
11 Referring to dilution ventilation command signals 31 A, B, and C, the signal 12 processing controller block 130 can produce these signals, portions of the signals, or all or a 13 portion of the control functions can be produced by the building control system 180. This is 14 shown for example in FIG. 2 with dilution ventilation command signal 3 1C
using sensor information, particularly air quality parameter sensor information from the shared sensors 16 220 in FIG. 2, and or the local room sensors such as 28C. Further, it should be clear that 17 signal processing controller 130 of FIG. 1, signal processing controller 210 of FIG. 2, or 18 signal processing controller 1130 of FIG. 6 need not be physically packaged within blocks 19 100, 200, or 1100 respectively and that it's possible to implement signal processing controllers 130, 210, or 1130 as either standalone modules, or to integrate them with some 21 other portion or system shown for example within Figures 1, 2, or 6.
22 With reference to FIG. 2, this diagram refers to another preferred embodiment of the 23 present invention directed to creating blended or composite air quality parameter 24 measurements and dilution ventilation airflow command signals using a networked air sampling system such as one similar to that described in U.S. Patent No.
6,125,710. This 26 sampling system has many of the functions and is similar to the system indicated in FIG. 1 27 with the main difference being that the solenoid switches and some of the controls are 28 distributed throughout the building vs. being located in one central unit.
As a result, central 29 sampling unit 100 shown in FIG. 1 is effectively replaced by sensor and control unit 200, 3o along with distributed air and data routers 300A, 300B, 300C, and 300D. The control of the 31 sequencing of the system and the signal processing functions are handled by signal 32 processing controller block 210. This block 210 carries out the functions of blocks 510 and 33 530 in FIG. 4, which will be described later. The shared sensor block 220 carries out the same 34 function as block 520 of FIG. 4 or block 120 of FIG. 1.
1 Blocks 300A, B, C and D are air and data routers that house the solenoid valves 2 361 A, 362A, 363A, 361B, 362B, 361C and 361D as well as potentially some analog or 3 digital input and output capabilities that are contained in Input/Output blocks 320A and 4 320B. As an example, air sampling location 23A is connected via tubing or air transport conduit 24A to solenoid 362A that is part of air and data router 300A. This tubing or air 6 transport media 24A along with 44A, 14, 44B, 54B, 24C and 64 was described earlier except 7 that the air transport conduit may also have associated with it some additional electrical 8 conductors for the purpose of adding networked data communication, low voltage power, 9 signal wires and other potential functions as described in U.S. Patent No.
filed on September 23, 2004 entitled, "TUBING FOR TRANSPORTING AIR
11 SAMPLES IN AN AIR MONITORING SYSTEM", as well as U.S. Patent No. 7,360.461.
12 filed on June 10, 2005, entitled, "AIR MONITORING SYSTEM HAVING
14 TRANSPORTING AIR SAMPLES". Adding these conductors enables local sensors to be more conveniently and cost effectively added to 16 the system.
17 For example, sampling location 23A, as well as the other sampling locations 43A, 18 43B, 53B, 24C and 63, could also contain a local temperature sensor similar to that of local 19 sensor 25A integrated into the sampling location to sense the room or duct temperature. The signal from this temperature sensor or from other local sensors such as humidity, ozone, or 21 other local air quality parameter characteristics can be sent to the air data router 300 as a 22 digital data communications signal though a data communication cable such as a twisted pair, 23 twisted shielded pair, fiber optic cable or other digital data communications media.
24 Alternatively, the sensor information could be sent to the router 300 via an analog signal through one or more signal conductors as an analog voltage or current signal.
This analog 26 signal can then be converted to a digital signal by the 1/0 block 320A or 320B in the router 27 300A or 300B respectively.
28 These 1/0 blocks 320A and 320B can also monitor other air quality parameters or 29 signal inputs that may or may not be directly associated with an air-sampling inlet yet would have a data communications cable, analog signal cable, or other connection to the I/O block.
31 An example of one of these sensors is room sensor 27A which could be a temperature sensor, 32 an air quality parameter sensor or other type of sensor such as a light, differential pressure, air 33 velocity or other building sensor such as an occupancy sensor or occupancy switch, or even 34 another type of switch of some type such as local room switch 81. Of the latter sensors or 1 room switches, an occupancy sensor is defined in the context of this invention as a sensor that 2 can detect the presence of people in a space through infra red energy, motion, card access, or 3 other means, whereas an occupancy switch is defined in the context of this invention as a 4 room switch such as a manually operated light switch or other type of room switch operated by the occupant when they enter or leave the space. A room switch in the context of this 6 invention is defined as some type of switch that may be for example electrical, mechanical, 7 photonic, or pneumatic that is located in or near the environment that can be manually 8 operated to signal a change in state to a system connected to it. A room switch may for 9 convenience of sharing wiring be located in the same room location and possibly in the same 1o enclosure as the air sampling pickup. Other types of room switches or sensors could also be 11 connected to the I/O blocks 320 of the air and data routers 300.
12 Within the air data routers 300, the output of multiple solenoid valves can be 13 manifolded together with manifold 390A and B. These manifolds plus the outputs of 14 individual solenoid valves such as 361C in air and data router 300C or solenoid 361D in router 300D are connected together with tubing or air transport conduit 202 to transport air 16 samples to shared sensors 220 in the multipoint air sampling unit 200 as moved by vacuum 17 source 140. The control of the air and data routers as well as the communication of digital 18 sensed information and air quality parameter data from the VO blocks within the routers or 19 from the local sensors in the spaces back to the multipoint air sampling unit 200 is through data communications cable 201. The air transport media 202 can be constructed using the 21 same materials mentioned previously for tubing 24A and other connections from the spaces 22 20 to the routers 300. The data communications cable 201 can be made with any commonly 23 used data communications media such as twisted pair, shielded twisted pair, fiber optics cable 24 or other. Additionally in a preferred embodiment the air transport media 202 and the data communications media 201 can be combined into one structured cable as was described for 26 the connections between the rooms 20 and the routers 300.
27 As in FIG. 1 the multipoint air sampling unit 200 also connects to the Internet 170 to 28 send information about the environments to a password protected website for review by the 29 occupants or facility personnel. Again as in FIG. 1 the multipoint sampling unit 200 can also interface to and send data back and forth through data communications media 181 with the 31 facility's building control or management system 180. This can be done directly or through 32 one of many interface protocols such as BacNet, OPC, Lon by Echelon, XML or others.
33 In addition to the air and data routers 300 that can accept sensed input signals from 34 the spaces 20 and provide signal output 31 to help control the rooms 20, the building control 1 system 180 can also be used to accept various sensor input signals such as 29C from local 2 room sensor 28C and signal 82 from room switch 81. This information can be used by the 3 building control system directly for control and or communicated back to the multipoint air 4 sampling system 200. For example, if the room sensor 28C was a temperature signal, this information could be detected by the building control system 180 and combined with 6 absolute humidity or dewpoint temperature information for room 20C, derived from the 7 shared sensors 220 of the multipoint air sampling system, by either the building control 8 system or the multipoint air sampling system to create a relative humidity or enthalpy 9 measurement or signal for room 20C. The building control system 180 can also provide 1o control signals to help control the airflow in rooms 20 as shown by signal 31C to the room 11 airflow controller block 30C using shared sensor information from the multipoint air 12 sampling system 100 or 200 and potentially locally sensed signals, room switch information, 13 as well as other building information.
14 FIG. 3 illustrates a more detailed diagram of one of the monitored areas that is controlled by a room airflow controller and some of the airflow control and feedback devices 16 and signals used therein. Additionally, this diagram also includes a room return airflow 17 sensing and control device 41 and return airflow control signal 47 as well as room return 18 feedback signal 48. Supply airflow sensing and control device or devices 51 and supply 19 airflow control signal 57 and supply airflow feedback signal 58 are also indicated.
Although a return airflow control device is indicated, most buildings will only have a 21 supply airflow control device controlled by the room airflow controller. In these cases, the 22 return air is uncontrolled and typically makes it way back to the air handling unit from the 23 room or area via ceiling or other plenum spaces via an egg crate or other grill in the ceiling or 24 air transfer duct from the room to the plenum space or a return air duct.
Return airflow control devices are often used in those rooms where a certain pressure differential or airflow 26 volume offset is desired between the room and surrounding rooms such as in an isolation 27 room or operating room in a hospital, or a clean room. In other words an offset airflow is set 28 between the return and supply flow so that the room is always slightly negative, neutral, or 29 positive in airflow vs. surrounding areas based on the application.
Additionally, in some cases if the room may contain hazardous contaminants or for other reasons, it may be 31 desirable to completely exhaust the airflow from the room to outside. In this case, the room 32 return may be ducted to exhaust fans completely exhausting the room air and making what is 33 shown as a room return airflow control device effectively a room exhaust airflow control 34 device with the control algorithms to control the device by the room airflow controller 30 1 being similar to that indicated in FIG. 5 for a room return airflow control device at least with 2 respect to this simple situation.
3 If no return airflow control device is present in the room or area that is controlled by 4 room airflow controller 30, then FIG. 3 and the related control diagram FIG.
5 are still applicable except that the room return airflow control device 41 and its signals 47 and 48, 6 plus room offset command 32 and supply flow feedback signal 58, should be omitted from 7 the diagrams where they are indicated.
8 In FIG. 3, local temperature sensor 91 communicates through cable 92 to a 9 temperature controller 90. This temperature controller could be part of building control system 180, a stand-alone system, part of the room airflow controller 30, or part of a separate 11 system that controls the airflow in a space or room with a return or exhaust airflow control 12 device. Such a latter control system that includes either a room return or room exhaust and 13 supply airflow controller devices 41 and 51 respectively of FIG. 3, as well as the room 14 airflow controller 30, and controls at least room pressurization by maintaining either a given room pressure or volume offset between the room and adjacent spaces is referred to in the 16 context of this invention as a tracking airflow control system which may also be used for 17 example in critical environments, laboratories, hospitals, vivariums, and various types of 18 clean rooms. In this latter case the room airflow controller 30 may also be referred to in the 19 context of this invention as a tracking airflow controller.
The purpose of temperature control block 90 is to provide regulation of room 21 temperature which may involve sending a thermal load or temperature command 93 to the 22 room airflow controller 30 to increase or decrease the volume of conditioned supply airflow 23 into space 20. The temperature control 90 may also control a reheat coil to increase the 24 temperature of the supply air fed into the space 20 or perimeter heating coils in space 20 for further means of temperature control.
26 FIG. 5 is an exemplary embodiment of the control diagram for the room airflow 27 controller 30. The supply airflow is set by the higher of either 1) the room's temperature 28 control signal that represents the room's supply airflow requirement to maintain proper room 29 temperature or 2) the dilution ventilation command signal that represents the supply airflow 3o requirements for dilution ventilation based on contaminant levels in the space plus in some 31 cases the volume of supply air required to meet the space's occupancy based on the 32 measurement of space carbon dioxide levels. The minimum override or high select function 33 for these two signals is implemented as shown in FIG. 5 by high select comparator Block 34 34 which acts to take the higher of the two signals provided to it, passing which ever of the two 1 signals is higher at any given time. The first input into high select block 34 is the scaled 2 temperature command 93 for varying supply flow. This signal is scaled and potentially offset 3 as needed in scaling block 38 to put it on the same scale factor as the other airflow command 4 signal input into high select comparator 34, such as to a certain number of efin per volt for an analog voltage signal or scaled directly into a given set of units such as cfin or liters per 6 second for a software or firmware variable representing airflow. The second signal into 7 block 34 is the dilution ventilation command signal 31 which is generated with the assistance 8 of the multipoint air sampling system, or the building control system 180 and is again scaled 9 and offset as needed by scaling block 39 to put this command on the same scale factor as the other signal.
11 The command 57 for the supply airflow control device 51 is further shown created by 12 taking the output of the high select comparator block 34 and subtracting offset signal 32 from 13 it by subtraction block 37. The room offset airflow command 32 could be a fixed offset 14 setpoint such as 10% of the maximum supply or exhaust cfin, or it could be a signal from the building control system, multipoint air sampling system or the tracking airflow control 16 system that varies in a two state, multi-state or VAV fashion. The purpose of this offset 17 airflow signal or variable 32, if it is used, is to create a typically slight negative, positive, or 18 neutral pressure for rooms employing a room return or room exhaust airflow control device.
19 An exemplary application of the room offset airflow command 32 being a two state control signal is for signal 32 to be a value such as 10% of the maximum supply volume for normal 21 room operation. However, when a cleaning compound or other spill, or other emergency 22 condition is detected such as a fire or smoke release via some sensor, alarm system, or 23 manually with room switch 81, the room offset airflow can be increased from its normal 24 value by one of the controllers of the multipoint air sampling system 100 or 200, or the building control system 180. Increasing the offset airflow to a potentially much higher value 26 for example will reduce the supply airflow volume so as to create a large negative offset 27 airflow for the room to provide a measure of increased containment to prevent the spread of 28 potential spill vapors or smoke into other spaces.
29 Finally FIG. 5 shows an embodiment of how command 47 for the room return or 3o room exhaust airflow control device is created by first starting with the supply flow feedback 31 signal 58. This signal 58 is next added to the room offset airflow command 32 by summation 32 block 36. The resultant signal is the room return or exhaust command signal 47 that is used to 33 set and control the flow of the room return or exhaust airflow control device 41.
1 If the space or room controlled by room airflow controller 30 has no return or exhaust 2 control device 41, then there is no room offset command 32 or room return command 47.
3 Furthermore, the supply flow command 57 simply equals the output of the high select 4 comparator 34 with no subtraction block 37 required.
FIG.6 shows a preferred embodiment of a multipoint air sampling system as applied 6 to an air handling unit for monitoring and or control purposes. As shown in FIG. 6 return air 7 1001 for air handling unit 1000 comes for example from rooms 20 or other areas. As shown 8 return air 1001 comes from return duct 40A from room 20A, as well as from plenum space 9 40C which is provided return air by transfer duct 40B from room 20B and ceiling grill 42C
from room 20C. Return air may also come from other locations or areas in the building as 11 shown by return duct or plenum space 40D. The supply air 1014 provided by air handling 12 unit 1000 is provided to spaces in the building such as rooms 20A, 20B, and 20C through 13 supply ducts 50A, 50B, and 50C respectively. Although not shown, other areas or rooms of 14 the building such as for example corridor 10 may also be supplied by air handler unit 1000.
Return air fan 1002 and supply air fan 1011 are used to move the air through the building.
16 Prefilter 1016 is typically used in the location shown and is often a coarse filter that is used 17 on the outside air stream. This is followed by a typically more effective and higher grade 18 filter shown as filter 1008. Control of the temperature and humidity content of the supply air 19 can for example be controlled through cooling coil 1012 and heating coil 1013. Other combinations of filters and heating and cooling coils used with respect to an air handling unit 21 or similar roof top units for meeting various applications are well known to those skilled in 22 the art of designing air handling units.
23 Additionally, the control of the amount of recirculated return air 1005, exhausted 24 return air 1004, and outside air 1007 is through the control of exhaust air damper 1003, recirculated air damper 1006, and outside air damper 1067. These dampers can also be 26 airflow control devices as defined earlier for such devices as 41A in Fig.
1 or 2, although the 27 dampers or airflow control devices in FIG. 6 will typically be larger devices due to the larger 28 air volumes involved. The control signals to control these dampers are shown in FIG. 6 as 29 outside air damper control signal 1068, exhaust air damper control signal 1070, and 3o recirculated air damper control signal 1072. There are many methods and algorithms known 31 to those skilled in the art to control the relative positions of these dampers. Typically the 32 building control system 180 or an air handler controls unit 1015 will control these dampers to 33 meet various requirements of the building such as regarding the required amount of outside 1 air, matters of energy efficiency relating to the heating and cooling of the building, and 2 building pressurization.
3 To monitor the operation of the air handling unit 1000 and or to help control it more 4 accurately, reliably and more cost effectively them has been possible with prior art systems particularly with respect to the control of the amount of required outside air, several air 6 handler locations can be monitored with the use of a multipoint air sampling system such as 7 that shown in FIG. 6 as block 1000. Multipoint air sampling system 1000 is shown for the 8 purposes of illustration in FIG. 6 as a star configured multipoint air sampling system similar 9 to that of multipoint air sampling system 100 in FIG. 1. However, the invention is equally 1o applicable to a networked air sampling system such as that shown as blocks 200 and 300 in 11 FIG.2. Similarly, the invention could be used with a networked photonic sampling system.
12 To monitor most aspects of the operation of the air handler and to better control it, 13 one of the preferred sense locations as shown in FIG. 6 involves sensing the return air 1002 14 either before or after the return fan with air sampling location 1031 and local duct sensor 1021 which is typically a temperature sensor for most applications. Another preferred sense 16 location involves sensing the supply air typically after the fan and various heating and 17 cooling coils to better ensure a more homogeneous distribution of temperature and air 18 contaminants within the supply duct. This is shown in FIG. 6 with sampling location 1037 19 and local duct sensor 1027 which is also typically a temperature sensor. A
previously mentioned sense location involves sensing outside air. In FIG. 1 and 2 this is performed with 21 sampling location 63 and local duct sensor 65. In FIG. 6 outside air 1007 is sensed for 22 example in the outside air duct before the outside air damper 1067 and prefilter 1016 by air 23 sampling location 1023 and local duct sensor 1033 which is typically a temperature sensor.
24 Finally a location that may also be helpful to sense is in the mixed air plenum of the air handler where the mixed air 1009 of the air handler is present. This air is similar to the supply 26 air but has not been filtered, heated or cooled by the air handler so it more closely reflects the 27 mixed air quality parameter characteristics of the return air 1005 and outside air 1007. The 28 mixed air 1009 is sensed by air sampling location 1035 and local duct sensor 1025 which is 29 typically a temperature sensor for most applications. It is useful to note that care must be taken with the selection of the air sampling and duct sensor locations in the mixed air 31 plenum. In many air handlers the return and outside air may be poorly mixed in the mixed air 32 plenum before filter 1008 resulting in a non homogenous air contaminant and temperature 33 distribution due to the different values present in the return and outside air.
1 With respect to the sensed duct locations, when multipoint air sampling systems are 2 used to sample ductwork, plenums, air handlers or any other applications where flowing air in 3 a partially contained area such as a duct or pipe is to be sampled and measured with a remote 4 sensor, a tube or hollow duct probe may be inserted into the duct or partially contained space to withdraw a sample or else a hole can be made in the duct and a sample drawn from the 6 duct from a tube connected to the opening in the duct wall. Additionally however, as noted 7 above a separate temperature or other parameter or contaminant sensing probe or probes are 8 also needed to make whatever local sensor measurements are desired from these ducts or 9 partially enclosed areas. Multiple separate probes for both sensing the flowing air stream and for drawing air samples may be employed at these locations or a unique integrated sampling 11 probe that uses one probe for both local air characteristic measurements and for air sampling 12 may be used as described in the U. S. Patent No. 7.421.911. entitled 13 "DUCT PROBE ASSEMBLY SYSTEM FOR MULTIPOINT AIR SAMPLING".
14 This type of integrated duct probe or other nonintegrated duct probes may be used to sense any of the duct locations referred to in FIG.
1, 2 or 3.
16 Additionally, this patent application also refers to the use of air sampling duct probes that use 17 multiple sensing holes spread along a cross section of the duct to obtain a better average of 18 duct conditions. This type of multiple pickup sampling probe plus an averaging duct 19 temperature sensor that is also described in this latter patent application may be used advantageously for example to measure the mixed air 1009 of the air handler.
21 As shown in FIG. 6 multipoint air sampling system 1100 accepts the four previously 22 mentioned air sampling locations that are connected to the solenoid valves 1163, 1164, 1162, 23 and 1161 by air sampling tubes 1032, 1034, 1036, and 1038 from sampling locations 1031, 24 1033, 1035, and 1037 respectively. This tubing is similar to the tubing 24A
previously described with reference to FIG. 1 and 2. The air quality parameters at these air handler 26 locations are sensed by the shared sensors 1120 and processed by signal processing controller 27 1130 which can implement all the functions of Fig. 4 shown for signal processing controller 28 530. The solenoids 161 through 164 are also controlled by control logic block 1110. Finally 29 multipoint air sampling system 1100 can accept local room or duct sensor signals or information through sensor inputs block 1150. This block senses local duct sensors 1031, 31 1033, 1035, and 1037 through cables 1032, 1034, 10356 and 1038 respectively. These cables 32 are similar to the cable 26A described previously with respect to FIG. 1 and 2. Alternatively, 33 local duct sensors 1031, 1033, 1035, or 1037 may communicate their air quality parameter 1 information to sensor inputs block 1150 through wireless or wireless network means such as 2 a wireless mesh network.
3 The control or monitoring signal outputs of signal processing controller 1130 can be 4 provided for example to building control system 180 as shown, for control of the outside air damper 1067 or to other building systems or controllers such as the air handler controls block 6 1015 or more specifically to the outside airflow controller block 1200 which can be used to 7 generate outside airflow command signal 1075 and is described in more detail through FIG.
8 9. Although not shown in FIG. 6, the building control system 180, the air handler controls 9 block 1015, or another controller can be used to control the outside airflow into the building 1o using outside air damper 1067 plus additionally the other air handler dampers 1003 and 1005 11 with the help of the outside airflow command signal 1075 from the outside airflow controller 12 1200.
13 Additionally any of the control or sensing approaches, or control inputs or outputs 14 mentioned in FIG. 1, 2, and 6 can be applied to the system or approach of the other figures.
Similarly these same approaches or systems can be applied to a facility monitoring system 16 embodiment similar to that of either FIG. 1, 2, or 6 that are implemented not with a 17 multipoint air sampling system but instead using a fiber optic light packet sampling and 18 sensing system such as described in US Patent No. 6,252,689 and referred to in this patent as 19 a networked photonic sampling system.
The creation of blended air quality parameter signals involving the use of multipoint 21 air or photonic sampling systems begins with the creation of a virtual air quality parameter 22 signal that is creating by de-multiplexing the sensor stream signals of the shared sensors 23 blocks 120, 220, 520, or 1120 of FIG. 1, 2, 4, or 6 which is performed by the signal 24 processing controller block 130, 210, 530, or 1100 in FIG. 1, 2, 4, or 6 respectively. An implementation of a portion of the signal processing logic of the signal processing controller 26 block that does this de-multiplexing plus other functions is shown in signal processing 27 controller block 530 in FIG. 4. In this diagram the control functions can be implemented in 28 analog or digital logic or be implemented with computer software or a firmware program or 29 any combination of these. In FIG. 4, shared sensors 520 create one or a multiple of output signals or variables shown for example in the diagram as sensor signals 525, 526, and 527 31 representing the outputs of individual sensors C02, humidity (such as for example measured 32 as dewpoint temperature, absolute humidity, or water vapor concentration), and TVOC's 33 respectively. Although FIG. 4 illustrates the use of these three sensors, any number or type of 34 sensors can be used. Since the sensors are being multiplexed with the air samples from 1 multiple rooms, three in this example, the individual or "virtual" sensor signals for a given 2 room corresponding to, as mentioned previously, a sensor signal or represented software 3 variable for a given air quality parameter in that room or area must be de-multiplexed from 4 the signal stream of that air quality parameter. This is done within signal processing controller 530 by the de-multiplexers 531, 532 and 533 that de-multiplex the C02, humidity, 6 and TVOC sensor signals respectively using the control signals 511 from the control logic 7 block 510. Block 510 corresponds to control logic block 110 and 1100 in FIG.
1 and 6 8 respectively, as well as part of signal processing controller block 210 and part of control logic 9 block 310A, B, and C in FIG. 2. The output of the de-multiplexing blocks 531, 532, and 533 are individual or "virtual" sensor signals or software variables that represent the sensed air 11 quality parameters for rooms 20A, B and C. For example, signals 522A, B and C represent 12 the signals or variables for the sensed C02 levels in rooms 20A, 20B and 20C, respectively.
13 These virtual sensor signals will typically have a value representing the last de-14 multiplexed value that will be held constant at that level until the next sampling of the corresponding location for that signal which may occur every few minutes or more likely 16 every 10 to 30 minutes based on the needs of the application. At this point the signal will 17 change value to equal the new de-multiplexed value. This transition of state from one de-18 multiplexed value to the next de-multiplexed value can occur either as a rapid or 19 approximately step change in signal or it may occur gradually in a ramped manner lasting from several seconds in time up to many minutes depending on the desired properties of the 21 virtual signal, what may be being controlled with that signal, and how often the location is 22 being sampled. A preferred approach for signals used for control applications would be to 23 have a gradual change of value occurring over between 5 and 60 seconds.
24 If we again focus on the variables for Room 20A, then the signals for C02, humidity, and TVOC are 522A, 523A, and 524A respectively. As mentioned previously these 26 individual or virtual sensor signals 522A, 523A, and 524A can then be modified with an 27 offset and scale factor block 534A, 535A, and 536A respectively as needed or some other 28 control function can then be applied. Additionally, sensor inputs block 550 has as its inputs 29 local room or duct sensors which for example in FIG. 1 and 2 are shown as 25A, 27A and 27B. The signals from these sensors, 26A, 28A, and 28B are applied to the sensor inputs 31 block 550 which may buffer them and then provide these signals to the signal processing 32 controller 530. In particular for room 20A, signals 55 1A represents the signal from local 33 temperature sensor 25A and signal 552A represents the signal from local room sensor 27A.
34 As with the virtual signals the local sensor signals 551A and 552A can then be modified by 1 offset and scale factor blocks 561A and 562A respectively as needed or by some other 2 function other than or in addition to an offset and scaling function which typically provides 3 the function of Y=AX+B where Y is the output and X is the input. The modified signals 4 from blocks 534A, 535A, 536A, 561A, and 562A are then acted upon by multiple input function block 537A which in this example generally involves signals associated with room 6 20A. Alternatively, air quality parameter signals from other areas or duct locations could be 7 used as well by multiple input function block 537A such as for creating differential signal 8 versions of some of the air quality parameter signals. Additionally, although not shown in 9 FIG. 4 the signal processing controller can contain many multiple input function blocks implemented with hardware or with firmware, software, or a combination thereof to create 11 various blended air quality parameter signals for other spaces or rooms.
The output signals 12 from multiple input function block 537A such as dilution ventilation feedback signal 538A
13 may be further processed or modified by output control block 540A to for example generate 14 an output command signal such as dilution ventilation command signal 31.
For example control loop functionality such as shown in FIG. 8 or a threshold level comparator with or 16 without hysteresis such as that shown in FIG. 7 can be used in output control block 540A vs.
17 in function block 537A to convert a blended air quality parameter feedback signal produced 18 by the multiple input function block 537A into a command signal output that can be used to 19 control a minimum supply airflow level for dilution ventilation or other purposes.
The multiple input function block 537A may also have multiple outputs as shown in 21 FIG. 4 where a second output 571A is shown which is a blended monitoring or feedback 22 control signal for relative humidity. The absolute humidity or dewpoint output 523A can be 23 combined with local temperature sensor output 551A using commonly known psychrometric 24 equations to create the relative humidity signal 571A or if desired other moisture related signals such as wet bulb temperature or enthalpy. This blended relative humidity signal 571A
26 can be used for monitoring or as a feedback signal that can be used by another controller to 27 control relative humidity levels in the space 20A or by another output control block similar to 28 540A to create a relative humidity command signal all from within the signal processing 29 controller 530.
Describing multiple input function block 537A in more detail, this block may for 31 example add signal inputs together; take the difference between different signals such as to 32 create differential signals; high select or take the higher of various signals; low select or 33 override various signals; apply threshold value or signal pattern trigger functions to the 34 signals either individually, as a group, or as subgroups to modify or create new signals; apply 1 control loop functionality similar to output control block 540A as is shown in FIG. 8; apply 2 hysteresis functions as shown in FIG. 7; apply any Boolean logic, linear, or nonlinear 3 function; or apply any other function or approach of benefit to blend or use these signals to 4 create blended monitoring or control signals. The result of block 537A is to create one or more of two state, three or multiple state, or continuously variable blended air quality 6 parameter signals that can be used as the basis for dilution ventilation feedback, dilution 7 ventilation command, outside air command, and other monitoring or control feedback signals.
8 Finally, this command or feedback signal or control variable may then be outputted to a 9 building control system or to another system as either a digital signal or variable such as dilution ventilation feedback signal 538A or as an airflow command signal or software 11 variable such as the dilution ventilation airflow command signal 31A
created by output 12 control block 540A and used as an input to room 20A's environments airflow control block 13 30A.
14 One other function that may be implemented within multiple input function block 537A or potentially in output control block 540A is a time delay or ramp function which is 16 most applicable when a discontinuous output signal is created such as two state, three state or 17 multiple state signal that is to be used in a control system. Since many control systems may 18 not respond in a stable manner to rapidly changing signals it may be helpful in some 19 situations to effectively create a continuously variable signal out of a multiple state signal.
For example, when a threshold value for a given air quality parameter signal or blended air 21 quality parameter is exceeded, the output of function block 537A or 540A
could be increased 22 to it's maximum or purge value that might correspond for example to a room air change level 23 of between 5 to 15 ACH's. This increase in value can occur instantly or may be commanded 24 to be a gradual ramp by function block 537A or 540A. Such a ramp or slowly increasing signal could occur over the span of a minute or more. This action may also be helpful to 26 prevent problems with the control system or the airflow control devices trying unsuccessfully 27 to keep up with a rapidly changing signal that could cause a pressurization problem in the 28 case of a space with a return or exhaust airflow control device such as in room 20A, if the 29 supply and return airflow control devices do not properly track the changing airflow command signals. Similarly, when the dilution ventilation command signal is meant to drop 31 from a higher level such as 10 ACH down to a lower or minimum level such as 2 ACH, the 32 function block 537A could create a slow ramp that gradually decreases the output signal 31A
33 over some period of time such as one minute or more.
1 Similarly these increasing or decreasing ramps or gradual changes in level could be 2 made linear, with constantly increasing or decreasing rates or made non-linear such as with 3 an exponentially changing rate so the ramp could start faster and gradually slow down or 4 conversely start slowly and gradually increase its rate of change in value until the signal hits it final value. These ramps could also be at different rates based on whether the signal is 6 increasing or decreasing. For example, it may be advantageous to rapidly increase the 7 ventilation of a room by rapidly increasing the dilution ventilation command 31 if a large 8 increase in the air quality parameter level in the room is detected. For example, a spill may 9 have occurred with a cleaning compound. However, it may also be helpful to have a slow 1o ramp downward; perhaps taking 5 to 15 minutes to gradually come down in dilution 11 ventilation flow to make sure that the air quality parameter is removed even to a level below 12 the threshold of detection.
13 In an alternative to ramping the changing flow over a large signal range, it may, for 14 the same reasons mentioned above, be desirable to change not just the rate of change of the output of block 537A or 540A such as for the dilution ventilation command signal 31, but 16 also the amount of the step change possible based on a change in the sensed air quality 17 parameters such as from the shared de-multiplexed sensor signals 522A, 523A, and or 524A.
18 In other words, rather than allow a full slew from the minimum dilution rate to the maximum 19 dilution rate from one air sample measurement, it may be desirable to limit the maximum step change in dilution ventilation airflow or effectively impose a slew rate limit on how fast a 21 rate the signal output of block 537A or 540A can change. The advantage of limiting the step 22 size or slew rate of the output signal is that for normal variations in the signal amplitude, very 23 little delay is created by this approach leading to more stable control. As an example of this 24 approach, a maximum step change size could be set for an increase in airflow representing two ACHs in a possible range from a minimum of two ACH to a maximum of eight ACH.
26 With the maximum step size set for example for two ACH, it would take three successive air 27 samples to have air quality parameter values in excess of the trigger values to boost the 28 dilution ventilation command signal 31 from the minimum to it's maximum value. Similarly, 29 if the maximum reduction was also limited to a flow rate equal to two AC it would take three successive measurements of the environment's air quality parameters to be below the trigger 31 value for the dilution command level to drop from a level corresponding to eight ACHs down 32 to two ACH.
33 In a manner similar to the ramp approach mentioned above, the increasing and 34 decreasing step heights may be of different sizes. For example, to respond quickly to a 1 cleaning chemical spill there may be no limit or a larger limit for an upward or increasing 2 change in dilution ventilation command signal 31. However, to ensure a large amount of 3 dilution to very low levels and reduce the possibility of an oscillation if the source is not a 4 spill, but a continuous emission, it may be advantageous to have a smaller decreasing step change size to hold the dilution ventilation at a higher level for longer periods so it takes 6 several air sample cycles to fully reduce the ventilation level to its minimum level.
7 Another means to set the step heights or possibly the ramp rates is based on the level 8 of detected air quality parameters or their rate of change. If a large value of an air quality 9 parameter and or a rapid rise in its level is detected since the last sample or recent samples, it may be advantageous to use different step change heights or ramp rates. For example in a 11 spill, where there is a sudden increase to a large air quality parameter value, it may be 12 prudent to immediately index the dilution ventilation command signal 31 to its maximum 13 value. Smaller or more gradual increases in value could be used when the sensed air quality 14 parameter moves with smaller steps or more gradual changes. On the other hand a sharp downward change in the sensed air quality parameter or blended signal might not change the 16 downward step level in order to keep the ventilation higher for a longer period of time to 17 better clean the air. Alternatively, for energy saving reasons and or if there happens to be 18 many brief upward excursions of air quality parameter levels that may not be hazardous, it 19 may be more beneficial, if the air quality parameter level has just rapidly dropped to below the trigger level to quickly drop the dilution ventilation command signal 31 to its minimum 21 level. As such, it may also be beneficial to have different step or output characteristics 22 associated with each air quality parameter. As a result, the output control characteristics 23 would be different based on which air quality parameter(s) triggered the need for more 24 dilution ventilation.
Output signals of the signal processing controller block 530 may also be used to 26 change the sampling sequence based on the detection of a spill, rapid increase in one of the 27 air contaminants, or a level of an air quality parameter that is of interest to more closely 28 observe. In this alternate approach the sequencing of air samples into the shared sensors from 29 the environments 20 may be altered through signal processing controller block output signal 512 that is used by control logic block 510 to modify the sampling sequence on a potentially 31 temporary basis during the period of a detected event of interest in a particular space 20.
32 Based on seeing the control signal or software variable 512 increase in value to some higher 33 trigger level or exhibit some signal pattern such as a rapid rise in amplitude, the control logic 34 block 510 might increase the frequency of the air sampling of the space where the event was 1 detected. Alternatively or additionally, the areas around the affected space may be quickly 2 sampled next or sampled at a higher frequency as well to look for a spread of the air 3 contaminant to other spaces. In the context of this invention a rapid rise in amplitude can be 4 defined as a sudden increase in value to a level such as many times larger than the normal trigger level in less than 5 minutes such as that seen due to a spill of a volatile organic 6 compound such as a cleaning compound.
7 This change in sampling or control sequence can be implemented with the sampling 8 system of either FIG. 1, FIG. 2, or FIG. 6. If the system of FIG. 2 was being used for 9 example, the detection of the event would be most likely carried out by the signal processing controller block 210 and the change in sequencing carried out by control logic blocks 31 OA, 11 310B, 310C and 310D.
12 Another change in control sequence that could be implemented if an event of some 13 type is detected in a space or several spaces would be to change the sampling sequence by 14 adding air sampling of several spaces at once to measure a mixed sample of several rooms.
This could be implemented for example, by turning on one or more solenoids at once to 16 gather a mixed sample of affected areas or of multiple areas nearby the affected area to 17 rapidly look for potential spillage into other areas. This would be implemented in the same 18 manner as mentioned above but would involve turning on multiple solenoid valves such as 19 for example solenoids 161, 162, 263, and 164 in FIG. 1 or solenoids 361A, 362A, 363A, and 361B in FIG. 2.
21 There are several different approaches that can be used for creating blended or 22 composite air quality parameter signals that can be used for monitoring only or for control 23 purposes such as for example the dilution ventilation command signal 31 or the outside air 24 command signal 1075. These blended signals can be implemented at least in part by the signal processing controller blocks 130, 210, 530 or 1130 of FIG. 1 2, 4, or 6 respectively, 26 building control system 180, or output control block 540A of FIG. 4 and outside airflow 27 controller 1200 of FIG 6 and 9. These blended signals, particularly the signals used for 28 control, have two important aspects. One component refers to the signal type, which also 29 impacts the control approach, such as two state, three or multiple states, continuously variable, or signal or control approaches that involve a combination of both discontinuous 31 and continuous functions. The other aspect refers to the makeup of the signal or how 32 multiple sensor signals are combined or blended to generate air quality parameter feedback or 33 monitoring signals as well as ventilation, outside air or other control and command signals.
1 One embodiment of a blended air quality parameter signal that can be used for 2 example for the dilution ventilation command signal 31 is a two state control signal whereby 3 dilution ventilation command signal 31 is maintained at it's minimum level, for example at a 4 dilution ventilation value corresponding to, for example, 2 or 4 ACH (or some other appropriate lower value depending on what's suitable for the environment being monitored), 6 unless a trigger event occurs that could consist of a threshold or trigger value being exceeded 7 by the sensor signal, particularly that of an air contaminant sensor such as for example 8 TVOC's, CO, or particles . If the sensor signal were to consist of just one air quality 9 parameter, a simple threshold or trigger value (corresponding to the value of the sensed air quality parameter at which some action is to be taken) can be defined.
Alternatively, the 11 trigger could consist of the signal matching in some way a specified signal pattern such as a 12 rapid increase in level even though a specified threshold level was not achieved. The trigger 13 event could also consist of a combination of one or more sets of threshold values and signal 14 pattern pairs, any one of which could constitute a trigger event.
If more typically, multiple sensor air quality parameters are being employed such as 16 from the shared sensors 120 and or a local room sensors 25A, the trigger event could be 17 defined as any one of the employed sensor signals exceeding a threshold value, matching a 18 signal pattern, or meeting the conditions of one of potentially multiple sets of threshold level 1g and signal pattern pairs. Each sensor signal would most likely have a different threshold value level and or signal pattern that corresponds to an appropriate value for the sensed air 21 quality parameter based on accepted levels of that signal related to one or a combination of 22 health, comfort or other criteria of importance for that sensed air quality parameter. For 23 example, a PID TVOC sensor would likely have a threshold level of about 0.5 to 2 PPM. A
24 level in this range senses many materials below their OSHA TLV (Threshold Limit Value) while still not generating many false alarms by staying above normal levels of less harmful 26 materials such as alcohol vapors. If a particle counter measuring in the range of 0.3 to 2.5 27 microns is used a level can be set that would not normally be exceeded such as in the range of 28 1.0 to 5 million particles per cubic feet, yet still pick up the evolution of smoke or some type 29 of aerosol generated by some event in a monitored space. The specific level could be set based on the level of filtration to the space, i.e. the more the filtration, the lower the level that 31 could be used. Other sensors such as a carbon monoxide, ammonia, nitrous oxide, ozone, or 32 other toxic gas sensor can be set directly for the TLV of the compound or for a lower level 33 that would not normally be reached in typical operation.
1 Although C02 based demand control ventilation is typically done with a continuously 2 acting or variable signal a simpler form of control can also be achieved by increasing 3 ventilation when the C02 levels in a room exceed some threshold level such as 1000 PPM, or 4 a value in the range of 800 PPM to 1500 PPM of C02, or a value of 400 to 1000 PPM above the ambient outdoor concentration of C02. These threshold values of C02 do not refer in any 6 way to health limits of C02 since C02 is in almost all situations not considered a harmful air 7 contaminant, but instead is a proxy for adequate rates of outside air per person since the 8 differential value of C02 in a space vs. outdoor levels also refers to the amount of outside air 9 ventilation in a space divided by the number of people, sometimes referred to as cfm outside air per person. The engineering organization ASHRAE (Association of Heating, 11 Refrigeration, and Air Conditioning Engineers) has set various guidelines for values of 12 outside air ventilation that vary for different types of facilities but are generally desired to be 13 in the range of 12 to 25 cfin per person which corresponds to between about 425 PPM to 14 about 875 PPM above ambient levels outside the building which can typically be between 300 and 500 PPM.
16 Alternatively, a triggering condition could consist of a combination of two or more 17 sensed air quality parameters each reaching or exceeding a given level for that compound or 18 meeting some signal pattern condition. For example, individually, a moderate level of fine 19 particles such as 1.5 million particles per cubic feet, a moderate level of TVOC's such as 0.5 PPM, or a moderate level of temperature excursion to above 85 degrees might in themselves 21 not trigger a need for increased dilution ventilation. However, the combination of all three 22 air quality parameters meeting the preceding conditions could indicate a fire or explosion that 23 would definitely require an increased level of ventilation.
24 A further implementation of a trigger condition involving multiple sensed air quality parameters could instead consist of an additive trigger condition. A good example of this 26 relates to exposure to hazardous materials. OSHA indicates that the effective TLV of a 27 mixture of gases can be computed by adding the fractions of each individual compound's 28 level vs. it's TLV to get the fraction of the combined mixture against the combined TLV. For 29 example, if the system detects that carbon monoxide is at 65% of the threshold limit value 3o and that sulfur dioxide is sensed to be at 70% of its TLV value then although individually 31 neither compound would trigger the system the combination of the two would be at 135% of 32 the combined TLV and as such would constitute a trigger condition. To implement this 33 approach each sensed air quality parameter of interest would be individually scaled based on 34 its threshold value and then added together and a threshold trigger set for the summed result.
1 For example, this could be implemented by first choosing a leading parameter to 2 perform ventilation control off of (C02, for example) and then scaling the other parameters 3 (particles, TVOC's, etc.) to be included in the composite feedback signal based on the ratio of 4 the trigger level of the leading parameter to that of the additional parameter. For example, if C02 is the leading parameter with a trigger level (setpoint) of 1000 ppm and TVOC's is a 6 secondary parameter with a trigger level of 30ppm the multiplier which "normalizes' or 7 scales TVOC's to C02 in this case is:
8 With these conditions, the TVOC reading is multiplied by 33.33 and then added to the 9 C02 signal, so that a controller with a setpoint or trigger point of 1000 ppm for C02 may be 1o used to limit TVOC's to 30ppm. Alternatively, the two signals can be high selected to each 11 other to create a blended air quality parameter signal that can then be compared to a signal 12 threshold level or control setpoint for simpler operation.
13 Another variation on how a trigger condition can be set up is to have the trigger 14 condition for one of more sensed air quality parameters vary or be changed based on some other air quality parameter or some other condition of the space. For example, a trigger 16 condition could be varied based on occupancy, if no one is in the space, the trigger conditions 17 for some air quality parameters might be raised slightly to save more energy by permitting a 18 lower ventilation rate and higher contaminant levels for unoccupied periods. The trigger level 19 could then be lowered when someone is detected or determined in some way to be in the space through, for example, an occupancy sensor or light switch, a card access system, or 21 other means such as the detection of changes in C02 in the space. There could also be 22 manual local, or remote override changes to the trigger levels, based on for example, an 23 increased or decreased concern about the air quality parameters in the room or space.
24 Alternatively, the levels could be changed automatically by the signal processing controller 130, 210, 530, or 1130 of FIG. 1, 2, 4, or 6 respectively, some other system such as the 26 building automation or building control system 180, or a tracking airflow control system.
27 Finally, any number of different logical or Boolean combinations of sensed air quality 28 parameter values or sensor signal pattern conditions acting on any number of sensed air 29 quality parameters affected by any other set of conditions or acted upon by other systems can be used to create a blended air quality parameter signal that can be used with the appropriate 31 trigger conditions to create a two state blended feedback signal that can call for increased 32 dilution ventilation by increasing dilution ventilation command 31.
33 There are a vast number of control techniques that may be used to generate command 34 31 using for example output control block 540A in order to vary the amount of ventilation 1 within the monitored environment 20 in order to dilute the sensed air quality parameter 2 sufficiently to prevent the concentration of the airborne air quality parameter from exceeding 3 a specific level. Any method that one may use, from a standpoint of control logic or 4 algorithm, whether it be an open or closed loop strategy involving continuous or discontinuous control functions, fuzzy logic, proportional-integral-derivative functions, feed-6 forward functions, adaptive control, or other techniques known to those skilled in the art of 7 control system design, are considered to be aspects of this invention.
8 FIG. 7A illustrates one possible scenario of steady-state levels associated with 9 command 31 when signal processing controller 130 is configured to provide a two-state control function such that dilution ventilation command signal 31 is increased to an enhanced ii dilution mode level from a normal level or ACH (air changes per hour) value when a blended 12 or composite air quality parameter signal or signals created by function block 537A for 13 example relating to environment 20 transition above an established trigger value or values.
14 Conversely, when the value of the blended air quality parameter signal or signals transition from a level that's above the appropriate trigger value to one below that value, command 31 i6 will drop back to its normal steady state airflow or ACH value. FIG. 7A
makes no reference 17 to the time response of command 31 as it transitions from the normal ACH
value to the 18 Enhanced Dilution mode and vice versa, as this is a function of the particular control ig technique used to make such a transition while ensuring that stability is maintained within the system. As an embodiment of this invention the two-state approach of FIG. 7A
can be 21 acceptable for use in many applications. However, in some cases the system stability realized 22 with the simple switching mechanism depicted by FIG. 7A will benefit by including 23 provisions to prevent command 31 or other commands such as outside air command signal 24 1075 from oscillating.
As an embodiment of this invention, when command 31 is transitioned from the 26 normal ACH value (1-4 ACH, for example) to the enhanced dilution mode (10-15 ACH, for 27 example), command 31 will be latched or become fixed at that higher value by for example 28 output control block 540A, so that following the transition if the measured air quality 29 parameter drops below the triggered value the air change rate will remain high. Such an 3o approach may be accompanied by some form of notification mechanism from the Building 31 Control System 180, or the sampling system 100, 300, 400, 1100 or via the internet 32 connection 171, or from the air flow controller 30 or some other component of the system 33 that airflow controller 30 connects to, which will alert maintenance personnel or other staff 1 that the trigger value has been exceeded so that signal processing controller may be manually 2 reset.
3 As an alternate embodiment, instead of latching command 31 when the value of the 4 sensed or blended air quality parameter exceeds an established trigger value, one may apply a hysteresis function as shown in FIG. 7B which depicts another scenario of steady-state levels 6 associated with for example command 31, in which two different triggers or transition points 7 are provided (input low trigger and input high trigger). Here the input high trigger is used 8 when the command 31 is at a level corresponding to the normal ACH value, while the input 9 low trigger is used when the command 31 is at a level corresponding to the enhanced dilution 1o mode.
11 A preferred signal type and resultant control approach for dilution ventilation 12 command signals 31 or other blended monitoring or control signals derived from air quality 13 parameter signals involves using three state signals to implement a three state control 14 approach. Unlike the previously mentioned signal type and control approach, which had two output levels such as a high level, typically for a purge, and a low normal operating level, this 16 approach has three output levels. A typical application for these three levels would be the 17 same two levels mentioned previously with an intermediate level added that is not for spills 18 (an extreme transgression in the levels of a sensed air quality parameter) but for controlling 19 more moderate levels of sensed air quality parameters that are desired to be lowered. For example, if a level of between 1 PPM and 10 PPM from the TVOC detector is sensed, the 21 system would increment up a moderate level, say from a minimum level of 3 ACH to a level 22 of 6 ACH's. However if the TVOC detector sensed levels above 10 PPM, then the system 23 would go into a purge mode with perhaps 10 to 15 ACH's of dilution ventilation. This 24 approach limits energy consumption for moderate air quality parameter levels and reduces the chance that if multiple rooms are at this moderate level, that the total system airflow capacity 26 of the building will be exceeded by too many rooms being commanded to maximum air 27 change rate (ACH) value. Another benefit of a three or other multiple level approach (or of a 28 VAV approach as well) is that it lessens the chance of realizing an unstable condition where 29 the room airflow can vary up and down due to a steady release of air quality parameters that 3o alternately is purged to a low value and then slowly builds back up as the system alternately 31 increases and overshoots and then decreases and undershoots the desired dilution airflow 32 command level by an amount that exceeds what is required for a stable operating condition.
33 The three state control approaches can be extended beyond three output states to any 34 number of output states for dilution ventilation command signals 31 to provide different 1 levels of dilution ventilation for a space. Finally any of the approaches to use multiple sensed 2 signals such as from the shared sensors 120 and or a local room sensors 25A
can as 3 mentioned previously for the two state approach, also be used for the three or other multiple 4 state control approaches with the addition of another set or additional sets of trigger levels and comparators for the intermediate or other output signal states.
Additionally, the output of 6 the comparators from multiple parameters can be added together so that for example if the 7 first or intermediate thresholds for two air quality parameters are crossed then the output 8 signal is indexed to the maximum flow or signal state for a three state signal or to the third g flow level or signal state in a multiple flow or multiple state air quality parameter signal vs. to only the second or intermediate level. Additionally there may be some air quality parameters 11 due to their hazard levels that even crossing the "first" threshold level requires the use of 12 much higher or potentially maximum flow or signal state with no or less other intermediate 13 threshold or trigger levels needed. Alternatively, in a preferred embodiment the air quality 14 parameters can be scaled to each other and then added together as mentioned previously to create a blended air quality parameter signal that can be compared to just one set of two or 16 more threshold levels. This latter approach is convenient for multiple output states or when it 17 is desired to change the threshold levels, requiring only one set of thresholds to be modified.
18 Another preferred type of signal and related control approach for creating and using 19 blended air quality parameter signals such as dilution ventilation command signals 31 is to use continuously variable signals that can be used to implement a variable air volume or 21 VAV control approach. With this signal type and control approach, once the sensed air 22 quality parameter signals reach some trigger level or match some signal pattern, the dilution 23 ventilation command signal 31 or the corresponding dilution ventilation feedback signal 24 538A can increase in a continuous manner from a minimum level which would match the minimum state output of the two or multiple state approach, all the way up to a maximum 26 level that would correspond to the maximum level of the two state or multiple state approach.
27 This effectively "infinite state" approach can be implemented as mentioned with the previous 28 control approaches by creating a blended air quality parameter signal from a plurality of 29 sensed air quality signals such as from the shared sensors 120 and or local room sensors such 3o as 25A that can be blended or combined in any manner. As before the individual air quality 31 parameter signals can be acted on individually and then added or high selected to form the 32 blended resultant signal. However, with continuously variable signals it is usually preferable 33 to first add or high select the scaled, offset or other wise modified air quality parameter 34 signals such as from the outputs from scale and offset blocks 561A, 562A, 534A, 535A, or 1 536A of FIG. 4 with for example the multiple input function block 537A
before applying 2 control loop, hysteresis or other functions to for example the blended feedback signal 538A
3 with output control block 540A of FIG. 4. Additionally, multiple input function block 537A
4 can also apply override or low select functions between the inputted air quality parameter signals or apply other linear, nonlinear or Boolean logic functions to the individually scaled 6 signals before or after combining these signals.
7 Output control block 540A can also apply linear or nonlinear functions to the blended 8 air quality parameter signals such as 538A. For example with a linear relationship an offset 9 and simple scale or gain factor can be used as well as a minimum and maximum clamp so io that as the dilution ventilation feedback signal 538A increases above the minimum command 11 signal value, the dilution ventilation command signal 31 will increase as well until it hits the 12 maximum allowed command signal value. Another of the reasons to use a continuously 13 variable signal state is to create closed loop control of the indoor environmental quality 14 within the monitored space or building so as to prevent an oscillating control pattern that might be generated in some situations by a two state or even a multi-state approach. With a 16 continuously variable signal state a variable air volume (VAV) control approach can be 17 implemented so that an increased ventilation level can be maintained in a stable manner i8 between the minimum and maximum command signal levels, particularly where there is a 19 roughly constant level of air quality parameter emission. This approach could be used to regulate the level of an air quality parameter such as a TVOC, particulate, or other at a certain 21 setpoint rather than drive it to a minimum level that could prove to be costly in terms of the 22 energy expense of running at high ventilation for extended periods. This approach is also 23 appropriate when the air quality parameter is not a particularly hazardous one and can be set 24 to be maintained at a level that would not create a health impact such as with particles. More particularly, by using a blended air quality parameter signal consisting of a plurality of air 26 quality parameters, the quality in a space can be maintained to a "cleanliness level" that 27 incorporates the control of many air quality parameters within one system or even one control 28 loop. In this approach where the blended air quality feedback signal can be controlled to a 29 setpoint value representing a measure of the combined state or cleanliness of the air in a space.
31 FIGs. 8A and 8B show a potential embodiment of the control logic and functionality 32 of output control block 540A that incorporates a closed loop system 900 to provide dilution 33 ventilation control by varying the air change rate or effectively the supply airflow rate within 34 a environment, such as 20, in a continuous (or VAV) fashion within prescribed limits in order 1 to prevent the level of a sensed air quality parameter, such as TVOC's for example or a 2 blended air quality parameter signal as described above, from exceeding a prescribed value.
3 Here, sensor feedback 908 which could be dilution ventilation feedback signal 538A of FIG.
4 4 is subtracted from air quality parameter set point 901, which represents the level of the sensed air quality parameter or blended set of parameters that system 900 is to control to, in 6 order to (by error stage 902) create error signal 914. Error signal 914 is acted upon by control 7 block 903 in order to create a term that is bounded by Min ACH Clamp block 904 and Max 8 ACH clamp 905 in order to yield the command signal 920. The command signal 920 may 9 represent the dilution ventilation command signal 31 of FIG. 4 or any other pertinent airflow to command or control signal such as the outside airflow command signal 1075 depending on 11 the nature and source of the sensed air quality parameter signal 908 and setpoint 901, 12 Command signal 920 in FIG. 8 is also the command to air flow block 906, which may be 13 composed of air flow controller 30 in FIG. 1, 2, and 3 and the return and supply flow (42 and 14 52) that it controls. Alternatively, airflow block 906 could be another control block such as air handler damper controller 1213 in FIG. 9 and the associated dampers or air flow control 16 devices 1068, 1070, and 1072 fo FIG. 6 representing the control devices for air handler 17 1000's associated airflows of outside airl 007, exhaust air 1004, and recirculated air 1005.
18 Also depicted in FIG. 8A is block 907, which represents the dilution characteristics of the 19 environment. For those who are familiar with the art of control system design, 907 represents the transfer characteristics of the environment which in this case defines how the air flow rate 21 of the environment under control relates to the value of the sensed air quality parameter 908.
22 Here, error stage 902, reverse acting control block 903, Min ACH Clamp 904, and Max ACH
23 clamp 905 may be implemented within output control block 540A or outside airflow 24 controller block 1200 of FIG. 6 and 9, or potentially within or partially within signal processing controller blocksl30, 210, 530, or 1130 of FIG. 1, 2, 4, or 6 respectively or within 26 Building Control System 180.
27 Control block 903 may be implemented using any of a large number of control 28 strategies known to those who are skilled in the art of control system design and may as an 29 example include any combination of proportional control, proportional-integral control, proportional-integral-derivative control, feed forward techniques, adaptive and predictive 31 control, and fuzzy logic strategies. One of the essential elements of control block 903 is that it 32 provide the necessary reverse acting and level-shifting functions so that it may properly act 33 upon error signal 914 (given the subtractive logic shown for error stage 902) in order to 34 create a command signal 920 which can yield an increase in the environment's air flow rate at 1 least for the condition where the sensor feedback 908 exceeds the air quality parameter set 2 point 901. (Alternatively, the logic of 902 could be altered so that 901 is subtracted for 908.) 3 As an example, quality parameter setpoint 901 may be set to 1.5 ppm and the sensed air 4 quality parameter may be, for example a blended signal created from sensing TVOC's (using, for example a photo-ionization detector -or PID sensor-) and carbon dioxide. Control 6 block 903 will be configured so that when sensor feedback 908 is less than setpoint 901 the 7 output of 903 will be less than or equal to the minimum clamp value established by minimum 8 ACH clamp block 904. 904 is a "high-select" block in that it will compare the value of the 9 output of 903 to some minimum clamp value (4 ACH, for example) and present the larger of 1o the two values to the next block 905. For example, if the output of 903 is 2 ACH and the 11 minimum clamp value set in 904 is 4 ACH, the output of 904 will be 4 ACH.
The output of 12 904 is presented to Max ACH clamp 905 which provides a "low-select"
function in that it 13 will compare the value of the output of 904 to a prescribed "max clamp"
value (12 ACH, for 14 example) and output the smaller of the two to air flow block 906. The way the system 900 works is that if there is some sudden increase in the level of the sensed air quality parameter 16 (due to a spill of cleaning compounds, for example) above the air quality parameter setpoint 17 901 (set to 1.5 ppm TVOC's for example) the control block will (within the limitations of 18 max clamp 905 set to 12 ACH, for example) increase command signal 920 to the value 19 necessary to limit a TVOC concentration within the controlled environment to 1.5 ppm. In practice, set point 901 can be set to a value less than the TLV for the air quality parameter or 21 blend of parameters to be sensed to insure that sustained concentrations will be limited to a 22 steady-state value that is safe. Alternatively, air quality parameter set point 901 may have a 23 dynamic value that adjusts based on the persistence of the air quality parameter monitored by 24 908.
FIG. 8B illustrates an alternate embodiment of system 900 that provides the same 26 control functions as FIG. 8A, but for any number "n" of air quality parameters using 27 individual air quality parameter feedback signals such as the outputs of 561 a, 562A, 534A, 28 535A, or 536A of FIG. 4 vs. the approach of Fig. 8A that uses a blended air quality parameter 29 feedback signal such as 538A of FIG. 4. With this approach, a dedicated error stage 902 and control function block 903 are provided for each sensed air quality parameter (1 through "n"), 31 with the nth sensed air quality parameter's set point shown as signal 909 going to error stage 32 910 which has an output 915 that is processed by function block 912. The outputs from each 33 control block, such as from control blocks 903 to 912, are presented to high select block 913, 34 which passes the largest of the control terms from the control blocks to airflow block 906 as 1 command signal 920. Using this approach, one can provide dilution ventilation control to an 2 environment such as 20 based based on a blended command signal 920 that is created from a 3 plurality of air quality parameters, such as TVOC's, particles, and a host of other air quality 4 parameters using individual setpoints such as 901 to 909 for each monitored air quality parameter as well as individual sensed air quality parameter feedback signals 908 or 911.
6 Effectively FIG. 8B allows the individual control function blocks 912 be individualized for 7 each air quality parameter which may be advantageous in some situations due to certain air 8 quality feedback signals potentially requiring different control gain and stability settings that 9 are best handled on an individual control loop basis vs. using one control loop and gain 1o settings and a blended feedback signal. With the implementation of FIG. 8B
the integration of 11 the control loops at the high select block 913 creates a blended command signal 920.
12 Additionally, for some situations block 913 may be implemented as a summation vs. a high 13 select block where each of the inputs to block 913 are scaled as necessary to allow the signals 14 to be properly weighted and summed with respect to each other.
Using the systems of FIG. 1, 2, 6, or the networked photonic sampling system, there 16 are several beneficial control implementations and methods that can be implemented to solve 17 problems that occur when trying to create and use blended or composite air quality parameter 18 based signals for use in the monitoring and control of building systems such as HVAC
19 systems. One application of these signals is in the control of outside air into a building or similarly controlling the amount of dilution ventilation or outside air provided into a space.
21 For example, the outside air that is being brought into the building may become slightly or 22 significantly contaminated by one or more air contaminants. Such air contaminants could 23 include carbon monoxide from auto or truck exhaust or from re-entrainment of furnace or 24 boiler exhaust, high levels of outdoor particulates, TVOC's that could be re-entrained from nearby exhaust stacks, or other outdoor sources of air contaminants. If these air contaminants 26 are not filtered out and pass into the supply air that is being fed into the rooms it could trigger 27 the dilution ventilation controls to increase the supply air flows and or the outside air flow 28 from the outside air intakes inappropriately. Similarly, the increase in supply air contaminants 29 may not be high enough to trigger increased supply air or outside air flow commands by itself, but added to existing air contaminant levels in the room or building it may make the 31 system overly sensitive to low or moderate air contaminant levels originating from within the 32 room or building. Both of these problems can produce potentially runaway results since the 33 control action of increasing supply or outside air which contains air contaminants only serves 34 to increase the level of the particular air contaminant within the room or building. This can 1 drive the supply or outside airflow levels even higher until no matter whether a two state, 2 three state, or VAV approach is used the supply airflow into the room or the outside airflow 3 into the building will eventually be commanded to its maximum level if the outside air or 4 supply system contamination is high enough. Since the supply system airflow potentially feeds many rooms, potentially all of these rooms could be pushed to their maximum flows or 6 else the amount of outside air being drawn into the building could reach potentially as high as 7 100% outside air. This could result in the airflow capacity and or the heating and cooling 8 capacity of the supply system being exceeded with potential resultant reductions of flow into 9 the room spaces and also potential loss of temperature control of these spaces if the 1o temperature of the conditioned supply air can not be appropriately controlled due to an 11 excessive amount of outside air being drawn into the building.
12 Alternatively in a building that uses return air such as is shown and implemented with 13 the air handling unit 1000 in FIG. 6, a high level of contaminants in one space may be 14 recirculated into other spaces through the return and then supply air. The correct action in this case would not be to increase room supply air in individual rooms but to instead 16 appropriately increase outside air to dilute the entire building including the space that is the 17 source of contaminants.
18 One exemplary control approach to solve these problems is to use a differential 19 measurement technique. In this approach an outside air or supply air measurement is subtracted from room air measurements to create differential measurements of the various air 21 contaminants of interest vs. either outside air or the supply air. Thus, if the outside or supply 22 air has an increase in particles, CO, TVOC's, etc., the air quality of the room air will be 23 evaluated against sources of air contaminants in the room only since the effect of the supply 24 air sources will be subtracted out. Effectively, we are concerned here not with the absolute air quality of the room air but whether it is being made worse by sources in the room or space 26 only, since increasing the supply or outside air to will not make the room cleaner if the supply 27 or outside air is the source of the air contaminant.
28 For example, as mentioned previously, we first start with air contaminant 29 measurements of the air in for example space 20A using for example room sampling location 23A, return air duct sampling location 43A, and or room sensor 27A in FIG. 1 and 2.
31 Alternatively as shown in FIG. 6 building level measurements such as from air handing unit 32 1000's return duct air sampling location 1031, and or the return duct sensor 1021 selected to 33 sense an air contaminant vs. temperature, may also be used. In this exemplary approach a 34 reference measurement of the air contaminants is next made based on the following 1 mentioned circumstances at either 1) the outside air using for example air sampling location 2 63 in FIG. 1 or 2, or the air sampling location 1033 in FIG. 6, or 2) the supply air using for 3 example the supply duct air sampling location 53B in FIG. 1 or 2, or the air handler 1000 4 supply duct air sampling location 1037 in FIG. 6. The specific location to be sensed, either one measuring the outside air or measuring the supply air, varies based on the type of air 6 handling system and the parameters of interest. For example, if the spaces are receiving 7 100% outside air directly from outdoors with no return air, then a measurement of either 8 supply air or outside air from within the outside air duct 60 of FIG. 1 or from outside air duct 9 sampling location 1033 of FIG. 6 will provide accurate results for at least gas or VOC
measurements. However, when at least particle measurements are a sensed air contaminant of 11 interest, it is important however that the reference measurement of the air contaminants be 12 taken at a location downstream from all the air filters and fan systems of the air handling unit 13 such as at the supply air duct sampling locations 1037 or 53B mentioned above. This 14 requirement is due to the impact of supply air handling unit filters such as prefilter 1016 and filter 1008 in FIG. 6 that changes the particle readings between a direct outside air 16 measurement and one of the supply air after the filters. Consequently, for this latter situation 17 and these reasons, the reference measurement should not be taken directly from an outside air 18 measurement.
19 Furthermore, if return air from other areas is mixed with outside air to produce the supply air as is shown with the air handling unit 1000 in FIG. 6, then the use of a downstream 21 supply duct airflow reference measurement instead of a direct outside air reference 22 measurement as a reference for space or area contaminant measurements is also necessary 23 with a location at least after where the outside air and return air become well mixed. This the 24 case for any air contaminant measurement involving return air systems even gases since the mixing of the outside and return air will potentially produce a different level of contaminant 26 in the supply duct vs what would be seen directly outside. The use of only one supply or 27 outside air duct measurement should be sufficient for all the spaces fed from a single air 28 handler or main supply duct since all the supply air flowing into these spaces from the same 29 air system should have similar characteristics and air contaminant values.
If on the other hand air contaminant measurements of building supply air or building 31 return air are being used to help control the amount of outside air brought into the building 32 then the appropriate reference measurement should be taken from outside air measurements 33 and not from supply air measurements.
1 The next step in this exemplary approach involves taking each pair of air contaminant 2 measurements (space or building air and outside or supply air) and converting them into a set 3 of differential measurements by subtracting the reference outside or supply air contaminant 4 measurement from the space air contaminant measurement, or vice versa if more convenient to do so. An example of an embodiment to perform this is the subtraction block 37 of FIG. 5 6 where a supply or outside air measurement of for example TVOC's would be applied to the 7 minus (-) input of the subtraction block and the space or return duct air contaminant 8 measurement of TVOC's would then be applied to the positive (+) input. The output would 9 then be the differential measurement of TVOC's for that space. Other methods of subtracting these air contaminant measurements for software variables in a computerized control system 11 for example or for other implementations would be known to those well skilled in the art.
12 The individual differential air contaminant measurements would then be treated in the 13 same manner described previously for the non-differential room air measurements and thus 14 would be used, for example, individually or combined and then compared or analyzed by signal processing controller block 130, 210, 530 or 1130 of FIG 1, 2, 4 or 6 respectively to 16 create air quality parameter feedback signals 538 or 1075 that can be further operated upon 17 by for example output command block 540A or outside airflow controller 1200 respectively 18 to yield command signals 31 to vary the supply airflow into space 20 and command signal 19 1075 that would be used or the outside airflow into the building.
The shared sensor multipoint air sampling system embodiments of FIG. 1, 2, or 6 are 21 preferred embodiments for this differential measurement control concept since the 22 measurement of the supply or outside air and the space air measurement can be performed 23 with the same sensor within a reasonably short period of time such as 5 to 30 minutes. As a 24 result many sensor errors are eliminated since they cancel out when subtracting the two measurements. Consequently, very accurate differential measurements can be made even 26 when the increase in air contaminants in the room although important is relatively small 27 compared to a potentially high source level of outside air or supply air contaminants. As a 28 result these high outside or supply background levels do not substantially decrease the 29 resolution or accuracy of the measurement of any air contaminant sources within the 3o environment spaces.
31 Another preferred control approach that can be used with the implementation of FIG.
32 1, 2 or 6 relates to a situation where a high level of supply or outside air contaminant may be 33 present, yet the differential room air signal mentioned previously indicates that there are not 34 substantive sources of air contaminants in the space. In this situation the absolute level of air 1 contaminants in the space may be high enough to trigger an increased dilution level, but the 2 differential signal correctly indicates that increasing the supply air is not appropriate. In this 3 situation, since the source of the air contaminant is the supply air, it may be advantageous to 4 reduce the supply air via supply air control device 51 and or the outside air through the outside air control damper 1067 until the outside or source air contains a lower level of air 6 contaminants.
7 One embodiment of this control approach consists of making one or more air 8 contaminant measurements in the supply duct 50B, outside air intake duct 60, or air handler 9 outside air duct sampling location 1033 as mentioned previously. These one or more air contaminant measurements can then be combined or used individually and then compared or 11 analyzed by signal processing controller block 130, 210, 530 or 1130 of FIG
1, 2, 4 or 6 12 respectively to determine if these signals exceed appropriate trigger levels such as those used 13 for the environment spaces 20. If these trigger levels or appropriate trigger conditions are 14 met, then blocks 130, 210 or 1130 can be used to reduce the supply and or outside air flow by one of several approaches. For example to reduce room supply flow, the temperature control 16 output 93 in FIG. 3 of the temperature control block 90 can be completely overridden and 17 effectively disabled by a command output from signal processing controller blocks 130 or 18 210 so that the supply flow will become controlled solely by the flow commanded by the 19 dilution ventilation command 31 which would be reduced to a low level. For example to reduce building outside airflow the outside air damper 1067 of air handler unit 1000 could be 21 commanded by signal processor controller 1130 to a lower flow rate representing the 22 minimum required flow rate for occupancy, versus a potentially higher rate for free cooling 23 with an economizer.
24 One particularly useful blended air quality parameter measurement that can be performed with this invention relates to enthalpy measurements. With reference to this, a 26 hygrometer is a device used to make moisture measurements, and typically provides a 27 voltage, current, or digital output that is representative of the moisture content of the air or 28 other gas that is sampled. The fundamental measurement made by a hygrometer is typically 29 dew point (or condensation) temperature or may be presented in terms of concentration, such 3o as parts per million -ppm- or parts per thousand ppt-, or some other suitable system of units.
31 Also, it is quite common for commercially available hygrometers to calculate other 32 psychrometric properties that may require a simultaneous measurement of a second property 33 of the sensed gas, such as temperature, in order to derive the desired property, such as 34 enthalpy and relative humidity, as well as other properties. Also, if absolute pressure is 1 known, the hygrometer's moisture measurement can be used to derive humidity ratio, which 2 is also provided by some commercially available hygrometers. For purposes of this invention, 3 a hygrometer may be based on any of various technologies known to those familiar with the 4 art of moisture measurement. These technologies include but are not limited to: chilled mirror hygrometers, infrared-based moisture analyzers, surface acoustic wave (SAW) technology, 6 aluminum oxide sensors, and sensors that combine an RH sensing device with a temperature 7 sensor in order to derive a dew point temperature, moisture concentration, or other suitable 8 measurement of moisture content from the sensed air or other gas being sensed. For 9 example, sources of some these types of instruments include for example a chilled mirror hygrometer tha can be provided by Edgetech Moisture and Humidity Systems of 11 Marlborough, MA or an infrared-based moisture analyzers such as the LICOR
840 unit that 12 can be obtained from LICOR Biosciences corporation.
13 When a derived psychrometric property such as enthalpy, RH, and other temperature 14 or pressure dependent properties is measured by such hygrometer devices, the accuracy of the derived parameters (RH, enthalpy, etc...) is highly dependent on the accuracy of the local 16 measurement of temperature or pressure that is simultaneously made by the device.
17 Therefore, when applying such hygrometer devices to multipoint sampling systems, only the 18 fundamental dew point temperature or moisture concentration measurement that it provides is 19 usable as most of the derived psychrometric properties (such as RH and enthalpy) will actually be altered as an air sample is transported from a sampled location to the shared 21 sensor location 220 (FIG. 2) of the multipoint sampling system, due to (for example) the 22 difference in temperature between the sampled location and the shared sensor location 220.
23 The formulation of an enthalpy or other psychrometric property signal can also be 24 derived from psychrometric charts that are well known in the art. As an example, U.S. Patent No. 4,672,560, which is incorporated herein by reference, discloses an exemplary enthalpy 26 calculator.
27 One common way to compute RH from dew point temperature and ambient 28 temperature involves, for example, an interpretation of the Clausius-Clapeyron equation for 29 vapor pressure as set forth in Equation (1) below:
Eq. 1 31 where, E = Vapor Pressure, ES = Saturation Vapor Pressure, TA = Ambient 32 Temperature in Kelvins, and TD = Saturation or Dew Point Temperature in Kelvins.
33 Additionally, as is known to those familiar with the art of psychrometrics, there are numerous 34 other approximations that may be used to calculate vapor pressure and saturation vapor 1 pressure when temperature and dew point temperature are known, from which RH
and other 2 psychrometric properties, such as enthalpy, can be calculated.
3 By inspection of Equation (1), one can see that relative humidity is not only 4 dependent on dew point temperature TD , but that it is also dependant on ambient temperature TA. For example, using this equation, we can see that for a given dew point 6 temperature 51 degF (for example) if an air sample is taken from a location at 70 degrees F
7 by an air sampling system, and in the process of transport to shared sensors 220 (FIG. 2) 8 containing the hygrometer the sample's temperature increases to 75 degrees F, the RH of that 9 sample will change from about 51% RH to about 43% RH, which is significant when making such measurements. A similar problem exists when making remote measurements of other 11 psychrometric properties.
12 In one aspect of this invention, a multipoint air sampling system includes a 13 hygrometer included as one of its shared sensors 220 (FIG. 2) in a common sensor suite, 14 which sensor's moisture measurement for each sampled location (for example, 20A, 20B, and 20C) is combined with a local temperature measurement (such as 25A) made from each 16 sampled space to generate a signal (such as 181 which connects to a BAS, or signal 17 571 A),representing a temperature dependent psychrometric property such as for example 18 enthalpy or relative humidity for each sampled space 20A, 20B, 20C.
19 A multipoint air sampling system may include a hygrometer in the sensor suite that can be used in combination with local discrete temperature and even pressure sensors at 21 sensed locations to determine both absolute humidity and temperature for the sensed 22 locations to calculate a blended air quality parameter signal representing relative humidity, 23 enthalpy, humidity ratio, and other psychromentric properties. One important benefit of this 24 arrangement when applied to RH sensing, is that it provides a significant improvement over conventional systems using distributed RH sensors, which tend to drift significantly over 26 time. This is particularly the case when making RH measurements within a plenum or duct 27 work used in a building's ventilation system. For example, if a hygrometer is incorporated 28 with the shared sensors 220 (FIG. 2), the output temperature sensor 27B
(FIG.2) located in 29 duct 50B can be combined with moisture measurements obtained from sensed location 53B
in order to proved a highly accurate and drift stable measurement of RH and other 31 temperature dependent psychrometric properties from duct 50B. This has great advantages 32 over commercially available duct-mounted RH sensors which tend to be unreliable due to, 33 among other things, fowling related to the particulate matter exposure of these sensors when 1 placed in an air flow stream. Also these discrete sensors tend to be expensive due to the cost 2 of the sensor element and the power supply and mechanical housing required.
3 Similarly, highly accurate and stable enthalpy measurements can be made according 4 to the teachings of this invention which provides a substantial improvement over conventional means of making such measurements. This is particularly important to 6 applications relating to the control of outside air (such as economizer applications), and other 7 air handler control applications.
8 An example of the creation and use of these blended enthalpy measurements plus 9 other blended air quality parameter measurements for outside air control purposes is shown in 1o FIG. 9 that shows a potential implementation for the logic and functions of the outside 11 airflow controller block 1200 from FIG. 6. In this diagram an enthalpy calculation for return 12 air 1001 is performed by the return enthalpy block 1205 using some of the psychrometric 13 relationships discussed previously and the air quality parameter measurements of return air 14 dewpoint or absolute humidity 1201 plus the return air temperature 1202.
These measurements are taken form sampling location 1031 and duct sensor 1021 respectively and 16 processed by the signal processing controller lock 1130 from FIG. 6.
Similar an outside air 17 enthalpy measurement is made by outside air enthalpy block 1026 using outside air dewpoint 18 or absolute humidity signal 1203 and outside air temperature signal 1204.
These 19 measurements are taken respectively from air sampling location 1033 and duct sensor 1023.
The two enthalpy signals outputted from blocks 1025 and 1026 are subtracted from each 21 other by subtraction block 1207 either as shown or with return air enthalpy subtracted from 22 outside air enthalpy signal. The resultant differential enthalpy signal is used in an economizer 23 controller 1208 as are commercially available and known to those skilled in the air that can 24 generate an outside air flow command to bring in more outside air when it would be less costly to do that vs. cooling return air. A manufacture of commercial economizer controllers 26 is Honeywell.
27 The free cooling outside airflow command from economizer controller 1208 can then 28 be further scaled and offset by function block 1209 and then acted upon by low select 29 comparator or override block 1210. The purpose of this block is to override and reduce the free cooling outside air command from the economizer 1208 when the outside air is 31 contaminated to a level where it would be better not to increase outside air if possible. To 32 implement this function outside air air contaminant measurements can be made and combined 33 and used by the low select comparator. This is shown for example with outdoor air quality 34 parameter signals 1221, 1223, and 1225 representing outdoor levels of particles, carbon 1 monoxide, and TVOC's respectively. These signals are then compared to their respective 2 threshold signals or setpoints 1220, 1222, and 1224. Comparators 1231, 1233, and 1235 3 individually compare these outdoor air contaminant signals and produce an output signals 4 that go high in either a two state, multi-state or continuously variable manner based on then difference of that threshold to the air quality parameter signal. These compared signals are 6 then provided to function blocks 1232, 1234, and 1236 which can scale and offset or apply 7 any other appropriate processing of these signals so they can be used by low select 8 comparator1210 to override either completely or on a partial basis the scaled output of the 9 economizer. Equivalently the outdoor air quality parameter signals could be combined and 1o blended into a blended outdoor air quality parameter signal and one comparator could be used 11 to create the override signal. Otherwise low select comparator 1210 combines and uses the 12 individual signals. The output of the comparator block 1210 is then scaled or modified by 13 another function block so it can be on the same scale or appropriate to be high selected with a 14 signal representing the amount of outside air necessary to provide for the amount of occupancy in the building based on C02 measurements as well as enough outside are to 16 properly dilute any air contaminants that happen to generated in the building.
17 The creation of this combined dilution and occupancy based outside air command 18 signal begins with air quality parameter measurements from the signal processing controller 19 1130 that may be based on de-multiplexed shared sensor measurements or local sensor readings. For example, the diagram indicates a potential setup using the measurements from 21 two rooms, 20A and 20 B, and two air quality parameter measurements for each room 22 namely C02 that is being used to determine the outside air volume requirements for 23 occupancy and TVOC's that is representative of an air contaminant measurement to 24 determine the amount of outside air required for diluting these air contaminants.
Alternatively, other air contaminants could be used as well as multiple air contaminants that 26 could be used to create a blended air contaminants signal. Furthermore as mentioned above it 27 is preferred to use differential measurements of air contaminants vs the appropriate reference.
28 When using room air measurements for controlling outside air into the building the 29 appropriate reference is outside air measurements. Therefore outdoor TVOC
signal 1225 is subtracted from Room 20A TVOC signal 1227 by subtraction block 1237. Similarly outside 31 TVOC reference 1225 is subtracted from Room 20B TVOC signal 1229 by subtraction block 32 1239. As has been mentioned before any of these subtractions or the ones for C02 can be 33 performed the other way around, with one signal being subtracted from the other or vice 34 versa. These difference measurements produce differential air contaminant signals 1241 for 1 room 20A and 1243 from room 20B are further processed by scale and offset blocks 1245 2 and 1247 respectively. These rooms or other rooms selected for either air contaminant 3 measurement or C02 occupancy measurements are typically chosen because they are 4 considered "critical zones" having then potential for either high occupancy or high levels of air contaminants.
6 For information on the occupancy requirements for outside air C02 is used as a 7 means to measure occupancy and the amount of outside air delivered to a space as has been 8 mentioned previously. To perform the appropriate measurement a differential measurement 9 of C02 is also desired since this difference vs. the absolute level of C02 in a space is what occupancy is directly based. Therefore outdoor air C02 signal 1226 is subtracted from room 11 20A C02 signal 1228 in subtraction block 1238 to generate differential C02 signal 1242 that 12 is scaled and offset by scaling block 1246. Similarly outdoor air C02 signal 1226 is 13 subtracted from room 20B C02 signal 1230 in subtraction block 1240 to generate differential 14 C02 signal 1244 that is scaled and offset by scaling block 1248. The respective scaled differential air contaminant signals can now be combined or blended in numerous ways based 16 on the desired control requirements. For example these signal can be high selected which is 17 preferred, or else they can be added together. One example is shown with the room 20B
18 where the differential C02 and TVOC signal are combined by blend function block 1249 to 19 generate one blended air quality parameter signal for that room, Room 20A's signal are shown used individually but are then high selected or combined in special function control 21 1250 along with the blended signal from room 20B. The output of special function control 22 1250 is a flow command signal that is high selected against the modified free cooling signal 23 to generate the final command signal for outside air 1075. Additionally, air handler damper 24 controller block 1213 can be used to create the actual damper control signals 1068, 1070 and 1072 corresponding to outside air, exhaust air, and recirculated air respectively for the air 26 handler 1000 potentially using feedback of outside airflow volume from outside airflow 27 measurement signal 1080.
28 Although specific features of the invention are shown in some drawings and not 29 others, this is for convenience only as some feature may be combined with any or all of the other features in accordance with the invention.
31 Other embodiments will occur to those skilled in the art and are within the following 32 claims:
33 What is claimed is:
|International Classification||F24F11/00, G01F23/00|
|Cooperative Classification||F24F2110/70, F24F2110/66, Y02A50/249, F24F2110/20, F24F2110/50, F24F2110/10, F24F11/30, Y02B30/767, F24F3/0442, G01N1/2273, F24F3/044, F24F11/0001, Y02B30/78, G01N1/26, G01N33/0063|
|European Classification||F24F11/00C, F24F11/00R9, F24F3/044B, F24F11/00R3C, F24F3/044, G01N1/26|