U.S. patent application number 11/668378 was filed with the patent office on 2008-07-31 for method for controlling multiple indoor air quality parameters.
Invention is credited to Mark Jackson, Shailesh Manohar, Raymond Wojcieson.
Application Number | 20080182506 11/668378 |
Document ID | / |
Family ID | 39668530 |
Filed Date | 2008-07-31 |
United States Patent
Application |
20080182506 |
Kind Code |
A1 |
Jackson; Mark ; et
al. |
July 31, 2008 |
METHOD FOR CONTROLLING MULTIPLE INDOOR AIR QUALITY PARAMETERS
Abstract
The present invention provides an improved method and system for
controlling an HVAC system for managing multiple indoor air quality
(IAQ) parameters. An acceptable range is defined for each of the
IAQ parameter. The parameters are then monitored by sensors within
a controlled space. The parameters may comprise temperature,
humidity, smoke, radon, VOCs, carbon dioxide, carbon monoxide,
particulates, hydrocarbons, oxygen, ozone, and odors. The invention
maintains the IAQ parameters within their respective acceptable
ranges by automatically manipulating certain HVAC system functions
including heating, cooling, humidification, dehumidification,
ventilation, addition or removal of materials or compounds which
affect IAQ parameters, airflow volume and air recirculation. In one
embodiment of the invention, a non-HVAC-specific venting system is
used to augment HVAC adjustment of airflow volume and air
recirculation. This may include bathroom, kitchen and attic venting
systems as well as whole-home vacuum systems.
Inventors: |
Jackson; Mark; (Irving,
TX) ; Manohar; Shailesh; (Coppell, TX) ;
Wojcieson; Raymond; (Carrollton, TX) |
Correspondence
Address: |
CARSTENS & CAHOON, LLP
P O BOX 802334
DALLAS
TX
75380
US
|
Family ID: |
39668530 |
Appl. No.: |
11/668378 |
Filed: |
January 29, 2007 |
Current U.S.
Class: |
454/354 |
Current CPC
Class: |
F24F 11/30 20180101;
F24F 2110/70 20180101; F24F 2110/72 20180101; Y02B 30/70 20130101;
F24F 2110/76 20180101; F24F 2110/50 20180101 |
Class at
Publication: |
454/354 |
International
Class: |
F24F 7/06 20060101
F24F007/06 |
Claims
1. A method for using a heating ventilation and air conditioning
(HVAC) system to control indoor air quality (IAQ), the method
comprising the steps of: (a) setting an acceptable range for each
of a plurality of IAQ parameters; (b) measuring said IAQ
parameters; and (c) controlling HVAC functions to maintain at least
one of said IAQ parameters within its respective acceptable
range.
2. The method of claim 1, wherein the IAQ parameters include at
least one of the following: volatile organic compounds (VOCs);
carbon dioxide; carbon monoxide; oxygen; ozone; radon; smoke;
odors; particulates, and hydrocarbons.
3. The method of claim 1, further comprising automatically
controlling a non-HVAC-specific venting system to augment HVAC
adjustment.
4. The method of claim 3 wherein the non-HVAC-specific venting
system comprises a bathroom exhaust vent.
5. The method of claim 3 wherein the non-HVAC-specific venting
system comprises a kitchen exhaust vent.
6. The method of claim 3 wherein the non-HVAC specific venting
system comprises a laundry exhaust vent.
7. The method of claim 3 wherein the non-HVAC-specific venting
system comprises a whole-house vacuum system.
8. The method of claim 3 wherein the non-HVAC specific venting
system is an attic fan.
9. The method of claim 1 wherein a measured IAQ parameter is a high
CO2 and the controlled HVAC function is increased ventilation.
10. The method of claim 1 wherein a measured IAQ parameter is a
high CO and the controlled HVAC function is increased
ventilation.
11. The method of claim 1 wherein a measured IAQ parameter is a
high radon and the controlled HVAC function is increased
ventilation.
12. The method of claim 1 wherein a measured IAQ parameter is a
high particulate level and the controlled HVAC function is
increased circulation and filtration.
13. The method of claim 1 wherein a measured IAQ parameter is a
high particulate level and the controlled HVAC function is
increased circulation.
14. The method of claim 1 wherein a measured IAQ parameter is a
high particulate level and the controlled HVAC function is shutting
down circulation.
15. The method of claim 1 wherein a measured IAQ parameter is a
high VOC level and the controlled HVAC function is ventilation.
16. The method of claim 1 wherein a measured IAQ parameter is a
high VOC level and the controlled HVAC function is increased
ventilation.
17. The method of claim 1 wherein a measured IAQ parameter is a
high VOC level and the controlled HVAC function is air
purification.
18. The method of claim 1 wherein control of an HVAC function is
based on a hierarchy of control.
19. A heating ventilation and air conditioning (HVAC) control
system that manages indoor air quality (IAQ), the control system
comprising: (a) a controller coupled to sensors that measure said
IAQ parameters and having a memory to store settings for an
acceptable range for each of a plurality of IAQ parameters; (b) a
processor that adjusts HVAC functions to maintain at least one of
said IAQ parameters within its respective acceptable range; and
wherein said HVAC functions may include heating, cooling,
humidifying, dehumidifying, ventilating, the addition or removal of
materials or compounds that otherwise affect IAQ parameters,
airflow volume, and recirculation of air.
20. The control system according to claim 19, wherein the IAQ
parameters include at least one of the following: volatile organic
compounds (VOCs); carbon dioxide; carbon monoxide; oxygen; ozone;
radon; smoke; odors; particulates, and hydrocarbons.
21. The control system according to claim 19, wherein the control
system also automatically controls a non-HVAC-specific venting
system to augment HVAC adjustment of airflow volume and air
re-circulation.
22. The control system according to claim 21, wherein said
non-HVAC-specific venting system comprises a bathroom exhaust
vent.
23. The control system according to claim 21, wherein said
non-HVAC-specific venting system comprises a kitchen exhaust
vent.
24. The control system according to claim 21, wherein said
non-HVAC-specific venting system comprises a whole-house vacuum
system.
25. The control system according to claim 21, wherein said
non-HVAC-specific venting system comprises an attic fan.
26. A controller for use with an HVAC-system comprising: (a) at
least one IAQ sensor; and (b) a control circuit coupled to both the
thermostat and IAQ sensor that produces an output in response to an
input from either.
27. The controller of claim 26 further comprises: (c) a sensor for
measuring temperature.
28. The controller of claim 27 further comprises (d) a display for
displaying a temperature and an IAQ measurement.
29. The controller of claim 28 wherein said display provides a
numerical read-out.
30. The controller of claim 28 wherein said display provides a bar
graph readout.
31. The controller of claim 28 wherein said display provides a
range readout.
32. The controller of claim 26 wherein said at least one IAQ sensor
comprises a particulate sensor.
33. The controller of claim 26 wherein said at least one IAQ sensor
comprises a CO.sub.2 sensor.
34. The controller of claim 26 wherein said at least one IAQ sensor
comprises a VOC sensor.
35. The controller of claim 26 wherein said at least one IAQ sensor
comprises a CO sensor.
37. The controller of claim 26 wherein said at least one IAQ sensor
comprises a radon sensor.
38. The controller of claim 26 wherein said at least one IAQ sensor
comprises a hydrocarbon sensor
39. The controller of claim 26 wherein said at least one IAQ sensor
comprises a ozone sensor.
40. The controller of claim 26 wherein said at least one IAQ sensor
comprises an odor sensor
41. A method for controlling indoor air quality (IAQ) parameters
comprising the steps of: (a) sensing the levels of IAQ parameters
(b) controlling non-HVAC venting systems to augment HVAC-venting
systems.
42. The method of claim 41 wherein the non-HVAC venting system
comprises a bathroom venting system.
43. The method of claim 41 wherein the non-HVAC venting system
comprises a kitchen venting system.
44. The method of claim 41 wherein the non-HVAC venting system
comprises an attic venting system.
45. The method of claim 41 wherein the non-HVAC venting system
comprises a whole house vacuum system.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present invention relates generally to a process or
method for controlling HVAC systems, and more particularly to
controlling HVAC systems according to multiple variables including
but not limited to measurements of indoor air quality
parameters.
[0003] 2. Description of Related Art
[0004] Simple heating ventilation and air conditioning (HVAC)
systems respond to or control merely one or two variables at a
time. Temperature is the one most often controlled. When the
environment is too hot or cold, a system turns on a heater,
furnace, heat pump, or air conditioner based on the settings of a
thermostat and adjusts the air temperature either upward or
downward to match a set point and keep the air in a controlled
space within a temperature range. Relatively sophisticated systems
can be programmed to different set points or ranges at different
times during a typical daily cycle.
[0005] HVAC systems typically control temperature with a single
temperature controller or thermostat which has the single control
input of dry bulb temperature and a single controlled output which
is the run time of the equipment and in some cases, the
recirculating air temperature. This equipment can have an effect on
other variables such as humidity in the controlled space during
operation. When moisture content is high, or when the thermostat
does not sufficiently run the equipment because of low dry bulb
conditioning requirements, the humidity can be excessively high.
Also, during periods of high humidity and relatively warm
temperatures in a controlled space, many air-handling units have
sufficient capacity to cool the space, but are incapable of keeping
the humidity at a sufficiently comfortable level. In such cases, a
separate humidity control unit can be added to the system.
[0006] FIG. 1A shows a typical HVAC system with a rudimentary
controller for a residential dwelling 110. With reference to FIG.
1A, an HVAC unit 140 pulls internal air into an inlet 106 and blows
it through air conditioning openings 108 throughout the controlled
space 102. The HVAC unit 140 usually attempts to control the
temperature of the air in the controlled space 102 through the use
of a temperature sensor 104 or thermostat and a feedback controller
(not shown). Thus, at most, the HVAC unit 140 can heat or cool the
air as it recirculates through the controlled space. Relatively
small volumes of air may also enter or leave the controlled space
102 through openings 116 to the outside 150 such as windows or
doors or other leaky openings.
[0007] Some residential and commercial HVAC units offer a slight
improvement over such rudimentary circulation by supplementing
recirculated air with an inlet stream of fresh air. In this way,
multiple air quality variables may be adjusted by controlling the
relative amount of inlet or fresh air flowing into the HVAC system.
Certain HVAC systems, including those in automobiles, commonly
include an inlet air controller such as a movable valve or shutter
(referred to herein simply as an inlet air valve) that is
positioned to control what proportion of the inlet air is drawn
from inside and outside the controlled space. In a typical
application, a system controller positions the air inlet valve to
optimize system efficiency and occupant comfort, and an occupant is
permitted to override the normal control when indoor air
recirculation or outside air ventilation is desired. For example,
air recirculation may be used to limit the intrusion of polluted
outside air, or outside air may be used to purge the controlled
space of smoke or odors. However, occupants frequently fail to
manually correct the inlet air valve to accommodate the prevailing
conditions in the controlled space. A need exists for a control
system that measures IAQ parameters in the controlled space and
makes adjustments automatically.
[0008] FIG. 1B shows a typical residential HVAC unit with just such
a limitation. With reference to FIG. 1B, an HVAC unit 140 pulls
inside air into an inlet 106, combines it with fixed volume of
fresh outside air taken from an outside air inlet 112, and blows it
through air conditioning openings 108 throughout the controlled
space 102. In addition, some HVAC systems purge some of the air in
the controlled space 102 through an exhaust vent 114. Through the
combination of adding fresh outside air and exhausting some stale
air, the HVAC system 140 reduces build up of air quality
contaminants. Simultaneously, an HVAC system 140 controls air
temperature in the controlled space 102 through the use of a
temperature sensor 104 and a feedback controller (not shown). The
HVAC unit 140 blows a fixed ratio of recirculated air and fresh or
makeup air throughout the controlled space. Such ratio can be
adjusted for comfort conditions, efficiency, or seasonal changes
and is not normally dynamically controlled in real time to adjust
for variations in air quality parameters. Likewise, no dynamic real
time adjustment is made for changes in the amount of air that
enters or leaves through windows and doors such as when occupants
enter or leave the controlled space.
[0009] In addition to the limitation of controlling just one or two
variables, all HVAC systems have a maximum volume of air for
ventilation through the controlled space. There is no systematic
means to supplement this ventilation volume. While other
ventilation systems exist in the house, for example bathroom and
kitchen ventilators, they are not integrated into a system which
controls ventilation levels for the building.
[0010] There have been some attempts at detecting and controlling a
single pollutant or environmental constituent depending on certain
conditions. For example, U.S. Pat. No. 6,916,239 issued to
Siddaramanna et al. on Jul. 12, 2005 ("patent '239") discloses a
method of controlling carbon dioxide levels in a controlled space
by changing the volume of air circulated, depending on the number
of human occupants in the controlled space. The '239 patent
discloses a method to control both carbon dioxide levels and air
temperature within a controlled space. Outside air is injected into
the controlled space when predicted carbon dioxide levels rise. The
carbon dioxide levels are predicted based upon a count of people
entering or exiting a controlled space. An alternative method of
controlling carbon dioxide levels in a space uses single or
multiple carbon dioxide sensors in conjunction with a controller to
adjust the amount of outside air injected to keep carbon dioxide
levels within a desired range.
[0011] Some newer HVAC systems control the indoor humidity within
certain limits in addition to temperature. U.S. Pat. No. 6,826,920
issued to Wacker on Dec. 7, 2004 (the "'920 patent") discloses a
humidity controller integrated with a constant volume air-handling
unit. The '920 patent discloses a system having an actuator
controlling a mixed air damper and actuator controlling both an
outdoor air intake damper and an indoor air exhaust damper. It also
teaches the use of humidity and temperature sensors placed outdoors
and within the controlled space, wherein humidity may be controlled
by slowing down the movement of air across the cooling coil of the
air-handling unit.
[0012] Despite the existence of a variety of improved HVAC systems,
improved sensors, and improved control systems, there remains a
need to control HVAC systems according to multiple variables
including those associated with air quality within a controlled
space, not just the "comfort" variables of temperature and
humidity. A need exists to simultaneously control temperature,
humidity, odors, and the level of inside air constituents and
pollutants, as well as a programmed set of responses to changes in
a variety of environmental variables. Furthermore, it would be
desirable to independently control such variables in a plurality of
controlled space compartments. The present invention fills these
goals and others as detailed more fully below.
SUMMARY OF THE INVENTION
[0013] The present invention provides an improved method and system
for controlling an HVAC system for managing multiple indoor air
quality (IAQ) parameters. An acceptable range is defined for each
of the IAQ parameter. The parameters are then continually monitored
by sensors within a controlled space. The parameters may include
temperature, humidity, and levels of smoke, radon, VOCs including
aldehydes, carbon dioxide, carbon monoxide, particulates, oxygen
(O.sub.2), ozone (O.sub.3), and odors. The invention maintains the
IAQ parameters within their respective acceptable ranges by
automatically manipulating certain HVAC system functions including
heating, cooling, humidifying, dehumidifying, the addition or
removal of materials or compounds that affect IAQ parameters,
airflow volume and air recirculation.
[0014] In one embodiment of the invention, non-HVAC-specific
venting systems are used to augment HVAC adjustment of airflow
volume and air recirculation. This may include bathroom and kitchen
exhaust vents, attic fans as well as whole-home vacuum systems.
[0015] In another embodiment, an improved thermostat is disclosed
that includes the additional sensors. This allows for a central
point of control. The thermostat may include sensors for
particulates, radon, VOCs, carbon dioxide, carbon monoxide, oxygen,
ozone, hydrocarbons, smoke and odors.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The novel features believed characteristic of the invention
are set forth in the appended claims. The invention itself,
however, as well as a preferred mode of use, further objectives and
advantages thereof, will be best understood by reference to the
following detailed description of illustrative embodiments when
read in conjunction with the accompanying drawings, wherein:
[0017] FIG. 1A is a schematic view of a controlled indoor space
showing air temperature control according to the prior art;
[0018] FIG. 1B is a schematic view of a controlled indoor space
showing air temperature control along with fresh air input and air
exhaust according to the prior art;
[0019] FIG. 2 is a schematic view of a controlled indoor space
showing elements of an improved method to control indoor air
quality according to a first embodiment of the present
invention;
[0020] FIG. 3 is a schematic view of a controlled indoor space
showing elements of an improved method to control indoor air
quality according to a second embodiment of the present
invention;
[0021] FIG. 4 is a response matrix or table showing possible
actions taken in response to changes in at least one indoor air
quality parameter or constituent;
[0022] FIG. 5 shows alternate embodiment of the present invention
in which the traditional airflow and venting passages of the HVAC
system are supplemented with additional venting systems commonly
found in homes;
[0023] FIG. 6 illustrates the optimization relationships between
IAQ components and conditions for which the HVAC system must
compensate; and
[0024] FIG. 7 illustrates a controller that incorporates thermostat
controls and IAQ sensors and controls as well.
DETAILED DESCRIPTION
[0025] While the invention is described below with respect to a
preferred embodiment, other embodiments are possible. The concepts
disclosed herein apply equally to other processes and methods to
control indoor air quality (IAQ) parameters. in a controlled space.
These IAQ parameters include comfort components such as temperature
and humidity and traditional IAQ components such as levels of
radon, VOCs including aldehydes, carbon dioxide, carbon monoxide,
particulates, oxygen (O.sub.2), ozone (O.sub.3) and odors.
[0026] The present invention is an improved method for controlling
IAQ parameters by controlling airflow throughout an enclosed or
controlled space, including individual zones within such space.
FIG. 2 illustrates one embodiment of the elements used in the
present invention wherein a dwelling or living space comprises
three zones. With reference to FIG. 2, air is recirculated through
a controlled space divided into compartments, rooms, or zones. As
in most dwellings, there is some commingling of air between a first
zone 202, a second zone 204, and a third zone 206 as shown by the
arrows. Air flows counter-clockwise from an HVAC unit 240 through
air passageways into each zone 202, 204, 206 and returns to the
HVAC unit 240 through return vents 242, 244, 246 from each room.
Baffles 222, 224, 226 control the flow of air into each of the
respective zones 202, 204, 206. Sensors 212, 214, 216 in each of
the zones 202, 204, 206 provide feedback signals to the controller
in the HVAC unit 240 or alternatively to a controller 250 located
within the space. The controller, which is located in the space,
would also communicate with the HVAC unit 240. Communication can be
through wires or alternatively through wireless means.
[0027] An outside sensor 218 allows the HVAC system to determine
the quality of the outside air 150. Fresh or outside air 150 enters
the controlled space through a separate intake vent. An intake
baffle 230 in conjunction with an exhaust baffle 228, control the
relative amount of fresh air versus recirculated air in the system.
Internal to the HVAC unit 240, one or more elements (not shown)
provide a continuous range of overall airflow to the controlled
space. Such range may extend from no airflow (off position) to a
maximum of several volumes of controlled air space per unit time
(e.g. ten volumes per hour).
[0028] Each sensor 212, 214, 216 may be a single sensor, a
composite sensor or may represent multiple sensors that provide a
feedback signal on a variety of air components and air conditions.
Additionally, each sensor may be in the return duct leading back to
the HVAC unit 240 from each of the zones 202, 204, 206. Such
signals are used to control system components or variables to
affect IAQ parameters.
[0029] The method of the present invention is illustrated with
reference to FIG. 2 according to various scenarios. In a first
scenario, when an IAQ parameter (e.g. VOC) enters a first zone 202,
a first zone sensor 212 alerts the HVAC system 240, which responds
by taking a variety of programmed actions. The HVAC system 240
increases the overall airflow within the controlled space and, if
possible, also changes the relative amounts of airflow through the
various zones 202, 204, 206.
[0030] The HVAC system 240 accomplishes this change by partially or
fully closing a second airflow baffle 224 and a third airflow
baffle 226 leading to the second zone 204 and third zone 206,
respectively. The HVAC system 240 also increases the opening of a
first airflow baffle 222 leading to the first zone 202. Finally,
the HVAC system maximizes the use of fresh or outside air 150 into
the controlled space. In this way, the pollutant is flushed as
quickly as possible from the controlled space and the first zone
202. This example assumes that the outside or fresh air is lower in
concentration of the pollutant. With reference to FIG. 2, the HVAC
system can make adjustments based upon a reading from an outdoor
sensor 218 regarding the amount of pollutant in the outside air
150.
[0031] In a second example, if the outside concentration of an IAQ
parameter is above an unacceptable level, and if a first zone
sensor 212 detects an increase of this IAQ parameter, the HVAC
system 240 responds differently. In this second scenario, the HVAC
system 240 maximizes recirculation of air within the controlled
space to minimize the chance of the outside IAQ parameter from
entering the system. The HVAC system 240 does this by closing an
exhaust baffle 228 and closing an input air baffle 230. It may also
optionally slow the overall flow of air throughout the controlled
space and if appropriate, turn on a device within the system which
removes the IAQ parameter of concern. If the second and third
sensors 214, 216 in the second and third zones 204, 206,
respectively, detect lower amounts of this IAQ parameter, the HVAC
system 240 circulates more air through the first zone 202 relative
to the second zone 204 and third zone 206 to flush out the IAQ
parameter from the first zone 202. As before, this is accomplished
by changing the relative positions of the airflow baffles 222, 224,
226. Once the indoor sensors 212, 214, 216 indicate that the level
of IAQ parameter has declined to below an acceptable limit, the
HVAC system returns to normal operation.
[0032] In a third scenario, if the second sensor 214 detects a high
level of carbon dioxide, the HVAC system 240 increases the overall
airflow to the entire controlled space and increases the relative
amount of fresh air injected into the controlled space. If the
second sensor 214 detects a high level of VOCs, the HVAC system 240
turns on a device within the system to reduce the VOCs by
absorption, adsorption, conversion or other means. The HVAC system
240 also responds by increasing the circulation of fresh air into
the controlled space as previously described, and increasing the
flow of air into the second zone 204 if possible.
[0033] In a fourth scenario, if the third sensor 216 detects a
relatively high level of particulates, the HVAC system 240 turns on
an internal filtration system (not shown) to filter out the
air-borne particulates. Such internal filtration system may be
within the air ducts returning to the HVAC system 240, or may be a
separate airflow system in fluid communication with one or more
zones of the controlled space. In addition, the HVAC system 240 may
increase the airflow to the third zone 206 where the high level of
particulates is found or to the entire controlled space so as to
keep particulates airborne and exposed to the filtration system. In
each scenario the sensors can communicate with a centrally located
controller 250, like the thermostat shown in FIG. 7. The connection
can be by wireless or wired network.
[0034] FIG. 3 is a second embodiment of the elements used in the
present invention wherein similar three zones are found within a
dwelling. In this configuration, air is circulated through a
controlled space divided into three zones 302, 304, 306. In this
dwelling 110, as mentioned in regard to FIG. 2, there is some
commingling of air between a first zone 302, a second zone 304, and
a third zone 306 as shown by the arrows. Unlike the embodiment in
FIG. 2, air flows counter-clockwise from an HVAC unit 340 through
individual air passageways into each zone 302, 304, 306. Air
circulated in this manner returns in separate air return lines to
the HVAC unit 340 through individual return vents 342, 344, 346 in
each room. Baffles 222, 224, 226 may be used to control the flow of
air into each of the respective zones 302, 304, 306. However, as
shown in FIG. 3, through the use of separate air lines, these
airflow baffles 222, 224, 226 are not required and airflow into
each zone 302, 304, 306 may be controlled directly within the HVAC
system 340.
[0035] With reference to FIG. 3, sensors 212, 214, 216 in each of
the zones 302, 304, 306 provide an electronic feedback signal to
the controller in the HVAC unit 340. When one of the sensors
detects the presence of a contaminant, the HVAC system 340
responds. For example, when the second sensor 214 detects an
abnormally high level of VOCs, the HVAC system 340 responds by
changing the airflow in the second zone 304 and possibly turning on
a device within the system, which removes VOCs. Specifically, the
HVAC system 340 increases the quantity of airflow entering and
exiting the second zone 304. The HVAC system 340 may also increase
the airflow or air pressure in the first zone 302 and the third
zone 306 so that the overall net flow of air is into the second
zone 304 and out through the second return duct 344 to the HVAC
system 340. With individual air passages into each zone, the HVAC
system 340 may blow recirculated air into the first zone 302 and
the third zone 306, and may blow fresh outside air 150 into the
second zone 304. The HVAC system 340 may blow heated air into the
first zone 302 and third zone 306 and may blow cool air into the
second zone 304 so as to further limit the diffusion of contaminant
out of the second zone 304. Alternatively, if a high level of
carbon monoxide is detected within the controlled space the HVAC
system 340 may slow or stop air recirculation, increase ventilation
and/or set off an alarm to alert the occupants of the controlled
space of the presence of unacceptable levels of carbon
monoxide.
[0036] The HVAC system 340 takes corrective action until a
detectable contaminant has reached an acceptable level. The HVAC
system 340 may take other simultaneous corrective actions to
maintain the other controlled variables within desired ranges. For
other disturbances, the HVAC system 340 makes specific,
individually tailored corrective actions depending on the identity
of the contaminant or type of disturbance.
[0037] FIG. 4 illustrates the various actions 400 taken by an HVAC
system according to detected changes in dependent variables
according to one embodiment of the invention and any number of
scenarios such as those previously presented. FIG. 4 is by way of
illustration and should not be construed as a limitation on the
functions of the present invention. An HVAC controller 402 measures
IAQ parameters 404. These measurements are conveyed to the HVAC
system 406. For comfort components, the system may perform as a
traditional HVAC system 408. However, for the measured IAQ
components 410, the system will perform in other ways to mitigate
and control the IAQ parameters. For high CO.sub.2 or radon
measurements 412, the HVAC system will open ventilation dampers 414
and allow more fresh air into the controlled space. The system may
also activate a whole house vacuum system, which is typically
driven by a blower located in the home's garage or basement.
Alternatively, or in supplement thereof, the system can activate
the kitchen, bath or laundry exhaust systems. The controller 402
will activate the vacuum, which will then vent the CO.sub.2 or
radon from the controlled spaces having access ports to the whole
home vacuum system. Covers over the ports may be opened to create
access between the controlled space and the vacuum system. For this
system to be more effective, the vacuum system could be vented to
the outdoors. In the event that the measured IAQ parameters
indicate high particulates 420, then the fan may be run
continuously through filtration media 422 until the particulate
count reaches an acceptable level. Alternatively, the system may
simply shut-down if the level of particulates indicates a fire. In
the case of high volatile organic compounds (VOCs) 430, the system
may again ventilate the controlled space to the outside. It may
also activate an air cleaner 432 such as a PCO (photocatalytic
oxidation) device that uses ultraviolet light to break down the
VOCs.
[0038] FIG. 5 shows another embodiment of the present invention in
which traditional airflow and venting passages of the HVAC system
are supplemented with additional venting systems commonly found in
homes. In addition to HVAC air ducts, most homes include several
additional air venting systems associated with specific functions.
The two most common are kitchen exhaust systems and bathroom
ventilation systems. In addition, in some geographical areas, fans
are sometimes installed in homes to exhaust indoor air to the attic
for whole house cooling at night. Less common is a whole house
vacuum system, which provides a centralized vacuum that may be
accessed from multiple vent outlets throughout the house.
[0039] The present invention is able to complement the ventilation
capabilities of the HVAC system with these non HVAC-specific
ventilation systems. Referring to FIG. 5, the first zone 502 in the
controlled space may be the kitchen, which includes a vent 510. The
third zone 506 might be a bathroom with an exhaust vent 512. If the
home in question has a whole house vacuum system, it is likely to
have airflow outlets 514, 516, 518 in each room (zone) leading to a
common outflow vent 520.
[0040] The HVAC system 540 is able to control these additional
ventilation systems in order to supplement and fine tune the
functions of the HVAC baffles and airflow vents. For example, if
toast is burned in the kitchen, it may be most desirable to turn on
the kitchen exhaust fan in conjunction with supplying additional
air to the zone including the kitchen using the HVAC system 540. If
a fire occurs however, and there is an acute increase in smoke,
VOCs or carbon monoxide that the HVAC ventilation airflow paths
alone cannot compensate for within an acceptable time frame, the
system 540 may simply be programmed to shut down. A shut down could
also be initiated by a signal from a fire detector or a security
system. Similar to the system shown in FIG. 2, the non-HVAC venting
systems can be controlled by a centrally located controller 550.
The connection between the controller and the venting system can be
wired or wireless.
[0041] FIG. 6 illustrates the optimization relationships between
IAQ components and comfort components for which the HVAC system
must compensate. When dealing with multiple parameters, some of
which require different compensatory actions on the part of the
HVAC system, there must be a constant balancing of one parameter
against another. FIG. 6 shows a simplified graph that covers four
parameters: carbon dioxide, VOCs, temperature, and humidity.
Additional parameters may also be included, but for simplicity of
illustration, the present example is limited to four.
[0042] An optimal range is established for each parameter. The
control algorithm for the HVAC system attempts to keep all
parameters within their respective optimal ranges. If any of the
parameters, such as VOCs 604 and temperature 606, begin to move out
of this range, the HVAC system will compensate to bring it back to
optimal. In the example depicted in FIG. 6, both carbon dioxide 602
and humidity 608 are beyond their designated maximum, which would
trigger the HVAC system to adjust them. The HVAC system continually
balances the parameters against each other in order to keep them
within this range, and may rely on supplemental venting provided by
non-HVAC airflow paths as described above. In certain
circumstances, it might be difficult to keep all parameters within
guidelines at all times. To address such conflicts, a hierarchy of
control can be establish based on the relative importance of each
parameter. For example, one response to high CO2 levels is to
increase ventilation. Yet, in the summer, this might also result in
high humidity.
[0043] This invention also includes an improved HVAC controller 700
as shown in FIG. 7. The controller may look like a normal
thermostat having a case 702 and a display 704. A series of sensors
706 may be located in the case 702. Alternatively, the sensors can
be located throughout the controlled spaces as shown in FIGS. 2 and
5. The sensors could be modular so that a select set of sensors may
be used. For example, this HVAC controller might have temperature
and relative humidity sensors, CO.sub.2 and radon sensors, a
particulate sensor and a VOC sensor. For a simpler controller,
maybe only a CO.sub.2 sensor is included. The display includes
readings for temperature 708, and relative humidity 710. For these
values, users are well accustomed to seeing and understanding
numerical values. However, for a factor such as CO.sub.2, a user
may be better served with a bar graph showing acceptable ranges and
a current reading located on that bar 712. The same is true for a
contaminant such as radon. For other IAQ parameters, such as
particulates and VOCs, it may be better to have a set of potential
ranges such as low, medium and high 714. The present HVAC
controller is flexible and may provide for each of these forms of
readout.
[0044] The foregoing discussion of the invention has been presented
for purposes of illustration and description. Further, the
description is not intended to limit the invention to the forms
disclosed herein. Consequently, variation and modification
commensurate with the above teachings, within the skill and
knowledge of the relevant art, are within the scope of the present
invention. The embodiment described herein and above is further
intended to explain the best mode presently known of practicing the
invention and to enable others skilled in the art to use the
invention as such, or in other embodiments, and with the various
modifications required by their particular application or uses of
the invention. It is intended that the appended claims be construed
to include alternate embodiments to the extent permitted.
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