throbber
(12)Un1ted States Patent
`(16) Patent N0.:
`US 6,478,233 B1
`
`Shah
`(45) Date of Patent:
`Nov. 12, 2002
`
`USOO6478233B1
`
`(54) THERMAL COMFORT CONTROLLER
`HAVING AN INTEGRAL ENERGY SAVINGS
`ESTIMATOR
`
`(75)
`
`Inventor: Dipak J. Shah, Eden Prairie, MN (US)
`.
`(73) Ass1gnee: Honeywell International Inc.,
`Morristown, NJ (US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`( * ) Notice:
`
`(21) Appl. NO': 09/751’730
`(22) Filed:
`Dec. 29, 2000
`
`(51)
`
`Int. C1.7 ......................... G05B 13/02; G05D 23/00
`
`(52) US. Cl.
`
`......................... 236/46 R; 236/47; 236/94;
`700/36
`
`(58) Field of Search ................................. 236/47, 46 R,
`236/91 R, 91 D, 94; 62/126; 165/111.1;
`700/36
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`4,685,615 A *
`8/1987 Hart ............................ 236/94
`3/1993 Shah ........................ 236/46 R
`5,192,020 A
`
`9/1996 Shah ................... 165/239
`5,555,927 xx
`5,717,609 A *
`2/1998 Packa et a1.
`............... 165/11.1
`* cited by examiner
`Primary Examiner—William Wayner
`(74) Attorney, Agent, or Firm Kris T. Fredrick
`
`(57)
`ABSTRACT
`A thermal comfort controller using various recovery meth-
`ods to change the indoor temperature to meet set points in a
`setup/setback schedule to maintain thermal comfort for
`occupants of an enclosure. The thermal comfort controller
`further comprising an apparatus to determine the expected
`energy savings When modifying the setup/setback schedule
`for the enclosure in which the temperature controller is used.
`The energy savings information may be displayed to the
`enclosure occupant for further consideration.
`
`19 Claims, 4 Drawing Sheets
`
`13
`
`1
`
`'/
`
`17
`
`9
`
`15
`
`11
`
`1
`
`N EST 1007
`
`1
`
`NEST 1007
`
`

`

`US. Patent
`
`Nov. 12, 2002
`
`Sheet 1 0f4
`
`US 6,478,233 B1
`
`
`
`FIG. 1
`
`2
`
`

`

`US. Patent
`
`Nov. 12, 2002
`
`Sheet 2 0f4
`
`US 6,478,233 B1
`
`17
`
`9
`
`15
`
`/ E
`
`:-
`
`13
`
`11
`
`FIG. 2
`
`3
`
`

`

`US. Patent
`
`Nov. 12, 2002
`
`Sheet 3 0f4
`
`US 6,478,233 B1
`
`12AMTIMEOFDAY
`
`10PM
`
`6AM
`
`6PM
`
`8AM
`
`FIG.3
`
`O
`
`E
`
`12AM
`
`0
`
`8
`
`
`
`TEMPERATURE(°F)
`
`4
`
`

`

`US. Patent
`
`Nov. 12, 2002
`
`Sheet 4 0f4
`
`US 6,478,233 B1
`
` 12AMTIMEOFDAY
`
`10PM
`
`FIG.4
`
`8PM
`
`5:45AM7AM
`
`E< 9
`
`1
`
`70°
`
`68°
`
`60°
`
`
`
`TEMPERATURE(°F)
`
`5
`
`

`

`US 6,478,233 B1
`
`1
`THERMAL COMFORT CONTROLLER
`HAVING AN INTEGRAL ENERGY SAVINGS
`ESTIMATOR
`
`FIELD OF THE INVENTION
`
`The present invention relates to thermostats and other
`thermal comfort controllers. The present invention particu-
`larly relates to thermostats having energy saving estimation
`capabilities which also use adaptive intelligent temperature
`recovery.
`
`BACKGROUND OF THE INVENTION
`
`In traditional thermal comfort control systems, a thermo-
`stat initiates heating system operation when the temperature
`falls below the set point value. The heating system responds
`by injecting heated air into the enclosure until the tempera-
`ture within the enclosure has risen to a point above the set
`point value. In order to achieve more accurate temperature
`control, typical thermostats use an anticipation element so as
`to turn off the heating system before the actual set point is
`achieved. This anticipation causes the actual air temperature
`for the enclosure to be more accurately controlled at the
`desired set point. For many situations this type of control
`results in air temperature that is comfortable for the enclo-
`sure’s occupants. The above described principles of tradi-
`tional thermal comfort control are equally applicable to a
`cooling system, except that the anticipation function works
`in reverse,
`i. e., the anticipator initiates operation of the
`cooling plant before the set point temperature is exceeded.
`With the development of programmable thermostats,
`occupants are able to modify the temperature within the
`enclosure at predetermined time periods. Occupants can
`program the thermostat to follow a temperature set point
`schedule. For example, thermostats may be programmed to
`an energy saving condition (setback temperature in heating
`or setup temperature in cooling) and a comfort condition
`(setup temperature in heating or setback temperature in
`cooling). Typically,
`the thermostat
`is set
`to control
`the
`temperature at the comfort conditions when the occupants
`are awake or generally occupy the enclosure. Conversely,
`the thermostat can control the temperature at energy saving
`conditions when occupants leave the enclosure and when
`occupants go to sleep.
`The use of setback/setup schedules is known to provide
`energy savings in many situations. However, conventional
`programmable thermostats do not provide any information
`regarding how much energy is actually saved, or how much
`energy could be saved if the occupant were to modify the
`temperature set point setup/setback features. Estimates of
`expected energy savings using the setup/setback features
`have typically been inferred from tabulated data which is
`more than 20 years old. The tabulated data was typically
`based on the generic building constructions from the 1970s
`which had over-sized HVAC equipment. Because no two
`building constructions are identical in terms of occupancy,
`operation, and HVAC equipment sizes and installations, the
`anticipated energy savings due to setup/setback will be
`different for each application. The differences are magnified
`due to various factors such as internal loads, infiltration and
`exfiltration, solar gains, and the like.
`Today, buildings are designed and constructed taking
`energy conservation measures into consideration. Installed
`HVAC equipment is much more critically sized to meet the
`building heating and cooling loads at design conditions, and
`therefore does not have excess capacity.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`Moreover, modern thermostats, such as The Perfect Cli-
`mate Comfort Controller, Model Nos. PC/W—89xx, and
`Chronotherm IV, Model Nos. T86xx, manufactured by Hon-
`eywell International, Inc., use the tabulated data for energy
`savings estimates which is based on the assumption that the
`temperature set point changes from the energy savings value
`to the comfort value at the programmed time, and not any
`earlier. Yet,
`these modern thermostats have incorporated
`Adaptive Intelligent Recovery (AIR) algorithms. The AIR
`algorithms provide the thermostat with more efficient heat-
`ing and cooling system operation that starts the heating/
`cooling system before the desired time so that the actual
`temperature meets the desired set point temperature at the
`specified set point time, rather than the thermostat starting
`the system at the set point time.
`In view of the above, it is apparent that there is a need to
`provide a climate control system that provides a user with
`information regarding actual energy consumption for spe-
`cific enclosures, and accurate estimation of the energy
`savings for the enclosure if the setup/setback features of a
`programmable thermostat are modified.
`SUMMARY OF THE INVENTION
`
`In view of the foregoing, it is an object of the present
`invention to provide a thermostat that can determine the
`expected energy savings from temperature set point setup/
`setback for the building in which the thermostat is used. This
`thermostat also provides control of an indoor climate to
`intelligently change temperature according to a predeter-
`mined set point setup/setback schedule such that the thermal
`comfort of the occupants is maintained.
`A further object of the invention is to display the expected
`energy savings information to the enclosure occupant.
`In one embodiment of the present invention, the enclosure
`set point schedule is preprogrammed into the thermostat,
`including the temperature set points, both at the comfort
`condition and at
`the energy saving conditions (setup/
`setback). This schedule also includes the times of day at
`which the temperature set points are changed. The system
`further obtains the outdoor air temperature through the use
`of an outdoor air temperature sensor. An estimate of the
`potential energy savings from the programmed setup/
`setback schedule is then determined for the enclosure. This
`
`energy savings is based on the known characteristics of the
`enclosure and the HVAC equipment
`in operation. This
`energy savings information is then presented to the enclo-
`sure occupant.
`Additionally, the system allows the occupant to modify
`the temperature schedule, and receive similar information
`regarding potential energy savings resulting from this modi-
`fication. For example, an alternative or proposed setup/
`setback schedule can be input by the occupant. Based on this
`alternative schedule, the system of the present invention can
`provide an indication to the user of the amount of energy
`savings to be expected. The occupant can then determine
`whether it is desirable to modify the temperature schedule,
`based upon the estimated energy savings and a desired
`comfort level.
`
`A further object of the invention is to provide an indica-
`tion to the user of the amount of energy savings to be
`expected for a proposed change in single temperature set
`point operation.
`These and other objects not specifically enumerated
`herein are believed to be addressed by the present invention
`which contemplates a controller for a climate control system
`that has an integral energy savings estimator.
`
`6
`
`

`

`US 6,478,233 B1
`
`3
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a graphical representation of the present inven-
`tion in an enclosure.
`
`FIG. 2 is a schematic of present invention.
`FIG. 3 is a graphical representation of a conventional
`setup/setback feature.
`FIG. 4 is a graphical representation of a recovery start
`times of a thermostat using adaptive intelligent recovery.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`The description contained herein relates to the specific
`structures of a controller for a heating/cooling system, as
`presently contemplated. This description, however,
`is
`intended to be illustrative only and not limiting as to the
`scope of the present
`invention. For example, while the
`invention will be described in the context of a thermostat,
`the invention is applicable to a variety of climate control
`systems as well. Furthermore, while the invention is
`described for the heating mode of operation, the invention is
`equally applicable in the cooling mode of operation with the
`understanding that in the cooling mode of operation, the
`energy saving set point
`temperature is higher than the
`comfort set point temperature, and vice versa in the heating
`mode.
`
`As shown in FIG. 1, a thermostat 1 controls a heating/
`cooling system 2 (i.e., furnace, air conditioner, heat pump,
`or the like) to intelligently change temperature set points
`(setup/setback) to maintain thermal comfort for the occu-
`pants of an enclosure 3. The control of the heating/cooling
`system is represented by line 8. An indoor sensor 4 is
`operatively attached to thermostat 1, the connection repre-
`sented by line 5, for supplying the indoor dry-bulb tempera-
`ture. An outdoor sensor 6 is operatively attached to thermo-
`stat 1, the connection represented by line 7, for supplying the
`outdoor dry-bulb temperature.
`As shown in FIG. 2, the thermal comfort controller of the
`present invention, thermostat 1, comprises a controller or
`memory 9 operatively connected to a user input source 11
`and a user display 13. The user input 11 is preferably a
`keypad, but may be a touch screen, or have remote access
`capability for a PC, PDA, or the like. Display 13 is prefer-
`ably a LCD display, however, the display may be of any
`type. The memory/controller 9 is operatively connected
`(represented by line 17) to indoor sensor 4 and outdoor
`sensor 6. A calculator 15, operatively connected to emory 9,
`determines the expected energy savings between a prede-
`termined temperature set point in a setup/setback schedule
`and a proposed new temperature set point schedule for the
`enclosure in which the thermostat
`is used. The energy
`savings information is displayed on display 13 to the enclo-
`sure occupant for further consideration.
`As shown in FIG. 3,
`the heating mode setup/setback
`feature on a programmable thermostat permits a user to
`select a comfort condition Aand an energy savings condition
`B. Note that comfort condition Am the morning may be the
`same as or different from that in the evening, and also note
`that the energy saving condition B during the daytime hours
`may be the same as or different from that during the night
`through early morning hours. Additionally, the thermostat
`can have multiple and different comfort and energy saving
`set point temperatures (i.e., setup/setback schedules) even
`though FIG. 3 depicts only two of the many possible
`scenarios. The user may select a set point temperature 10 at
`a predetermined time, e.g., 70 degrees Fahrenheit at occu-
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`pant’s wakeup time of 6 am. The user selects the duration
`of the comfort condition A, typically until the occupants
`leave. Another time is selected for the beginning of the
`energy savings condition B, and the set point temperature for
`the setback 12, e.g., 60 degrees Fahrenheit at 8 am. The
`energy savings condition continues until another preselected
`setup temperature set point 14 arrives. For example, the time
`occupants return to the enclosure at 6 pm. and selected
`comfort condition Aof 70 degrees Fahrenheit, which is to be
`maintained until they go to sleep 16 at 10 pm.
`Adaptive Intelligent Recovery (AIR) is a process involv-
`ing a series of algorithms used to determine the precise time
`to activate the climate control system (i.e., heating or
`cooling system) to change the enclosure temperature from
`the energy saving condition to the comfort condition. Using
`these AIR algorithms, the actual heating and cooling system
`start times are altered to allow the enclosure to reach the
`
`the desired time. Through this
`desired temperature at
`process, the thermostat can develop knowledge about the
`enclosure. For example, the thermostat learns the enclosure
`temperature ramp rates that the heating/cooling system is
`capable of providing. Also, the thermostat can determine
`certain information about the thermal characteristics of the
`
`structure (e.g., thermal time constant, thermal loss).
`Most significantly, AIR algorithms cause the heating/
`cooling system to operate differently than was done with
`previous thermostats. Consequently, all of the previously
`mentioned data regarding energy savings is not applicable.
`The climate control system user may want
`to obtain
`information relating to energy savings if the heating mode
`setup/setback schedule is modified, as shown in FIG. 4. It
`should be noted that although FIG. 4 and the following
`associated description depicts a scenario for the heating
`mode of operation, the discussion is equally applicable for
`the cooling mode of operation wherein the energy saving set
`point temperature is typically higher than the comfort set
`point
`temperature. The original enclosure temperature
`response profile 18 for the heating mode has a comfort
`condition set point 19 of 70 degrees Fahrenheit at 6 am. The
`comfort condition has a two hour duration, ending 20 at 8
`am. The set point temperature setback process 32 begins at
`8 a.m., bringing the enclosure to the energy savings condi-
`tion. The climate control system then begins recovery to the
`next comfort condition 21 that begins at 8 pm. and ends 22
`at 10 pm. The setback period again begins at 10 pm. to
`return to the energy savings condition.
`However, the occupant may want to modify the setup/
`setback schedule to have a schedule 24 with a different
`
`comfort condition set point start time 23, such as 5:45 a.m.,
`with a decreased duration of only a one hour fifteen minutes,
`ending 30 at 7 am. The present
`invention provides a
`thermostat with the ability to present the enclosure occupant
`with a percentage of energy savings estimate for the pro-
`posed schedule modification.
`Alternatively, occupant may desire to modify the setup/
`setback schedule by changing the comfort condition start
`time and temperature 28. With a later comfort condition
`starting time 31 of 7 a.m., a lower set point temperature of
`68 degrees Fahrenheit, and one hour comfort condition
`duration ending 33 at 8 a.m., the present invention provides
`the occupant with an energy savings estimate for such a
`modified setup/setback schedule.
`The calculator of the present invention may also deter-
`mine the actual amount of energy saved by modifying the
`setup/setback schedule from a previous temperature set
`point(s) to the current temperature set point(s). Alternatively,
`
`7
`
`

`

`US 6,478,233 B1
`
`5
`the calculator may determine the amount of expected energy
`savings to be expected for a single temperature set point
`modification.
`
`For programmable thermostats that use set point tempera-
`ture setup/setback schedules for ensuring comfort conditions
`and saving energy, the preprogrammed time, the recovery
`ramp rate and duration of the recovery period are available
`within the thermostat logic as described in US. Pat. Nos.
`5,555,927 and 5,192,020, both of which are incorporated
`herein by reference. The data on the recovery ramp rate and
`duration of the recovery period,
`in conjunction with the
`availability of the enclosure space temperature set points
`both at the comfort condition and at the energy savings
`setup/setback conditions, the times of the day at which the
`temperature set points are changed, and the outdoor air
`temperature from an outdoor air temperature sensor may all
`be used to determine the potential energy savings from
`setup/setback for an enclosure and HVAC equipment being
`controlled by the thermostat.
`
`The data from the thermostat logic may be applied in
`several ways to determine the energy savings. Two
`approaches are described herein. Note that the temperature
`values are presented for a climate control system operating
`in the heating mode. The algorithms are equally applicable
`for a climate control system operating in the cooling mode.
`
`In a preferred embodiment, an energy balance on an
`enclosure results in the following equation for the time rate
`of change of the sensed enclosure temperature:
`
`am
`mop d1 = q — UA(TS — Tog) or,
`
`_ Ts—Toa
`dTS/dt
`
`(1)
`
`(2)
`
`£1
`fl _
`UA _ UAdTS/dt
`
`where:
`
`mcp=Overall thermal capacity of the enclosure,
`q=Time rate of heat
`input
`into the enclosure from a
`heating or cooling device,
`T5=Sensed enclosure temperature at time t,
`Toa=Outdoor air temperature at time t, and
`UA=Overall heat transfer coefficient of the system.
`In equation (2), the ratio of the overall thermal capacity of
`the enclosure, mcp, to the overall heat transfer coefficient of
`the system, UA, is commonly known as the overall thermal
`time constant of the system, '55, which is expressed as:
`
`TS:
`
`mcp
`UA
`
`50
`
`(3)
`
`Those skilled in the art will note that once a thermal
`
`time constant, as
`its thermal
`system has been defined,
`defined by equation (3), will not vary significantly on a daily
`basis, nor between two consecutive days in particular.
`However, it should be noted that since the thermal and heat
`transfer properties of any material could vary with its
`temperature, the thermal system’s time constant during the
`low cold temperatures of the winter months could conceiv-
`ably be different than during the higher warmer temperatures
`of the summer months. Those skilled in the art will note that
`the heat transfer coefficient, UA, will be different during the
`winter months than during the summer months, and that the
`heat transfer coefficient is also influenced by wind speed,
`wind direction, and many other factors.
`
`55
`
`60
`
`65
`
`10
`
`15
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`20
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`25
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`30
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`35
`
`40
`
`45
`
`6
`
`Substituting equation (3) into equation (2), one obtains:
`
`TS
`
`
`Ts — Toa
`q
`= UAdTS/dt _ dTS/dt
`
`(4)
`
`Equation (4) permits the determination of the thermal
`time constant when the heating/cooling system is turned
`OFF, i.e., q=0, thusly:
`
`TS:
`
`
`TS_Toa
`_ dTS/dt
`
`Equation (1) can be re-written as:
`
`am
`q = mcpm + UA(TS — TM) or,
`
`q _mcpdT+(T T)
`UA_UA d1
`5
`0" or’
`
`dT
`q
`m=ndf+<Ts—Tm)
`
`(5)
`
`(6)
`
`Equation (6) can be used to determine the instantaneous
`amount of energy required, q, to maintain the enclosure at a
`set point temperature Tsp’ One then integrates equation (6)
`over a period of time, for example, 24 hours, to compute the
`total amount of energy required to maintain the enclosure at
`the set point temperature TSPl for that period of time, and
`then again integrates equation (6) over the same period of
`time to compute the total amount of energy required to
`maintain the enclosure at a different set point temperature
`Tspz. The results of these two integration process, when
`ratioed, will provide an indication of the expected energy
`saving between two different set point temperatures. In the
`case of where setup/setback schedules are used in thermo-
`stats to maintain the enclosure at different set point tem-
`peratures at different
`times of day, equation (6) can be
`integrated to determine the amount of energy required to
`maintain the enclosure at the different set point temperature
`values, and also to determine the amount of energy required
`to recover from energy savings set point temperature value
`to comfort set point temperature value.
`In order to correctly determine, by integration, the total
`amount of energy required to maintain the enclosure at the
`energy savings set point temperature value, one needs to
`know the time at which the enclosure temperature will have
`reached the energy saving set point temperature value from
`the comfort set point temperature value. This is accom-
`plished by monitoring the time rate of change of the enclo-
`sure temperature and recording the time at which the enclo-
`sure temperature equals the energy saving set point
`temperature. Note, that in order to correctly determine the
`total amount of energy required for maintaining the enclo-
`sure at a set point temperature, the integration should not be
`done during periods when the heating/cooling system is
`OFF, i.e., the instantaneous amount of energy required, q,
`equals zero. Alternatively, a value of zero could be inte-
`grated into the total energy calculation whenever the
`heating/cooling system is OFF.
`The above identified equations and methodology may be
`used to estimate the total amount of energy required to
`maintain an enclosure at any setup/setback schedule. The
`computation for different setup/setback schedules can then
`be compared to determine the approximate amount of
`energy savings that may be expected between alternatives.
`In another embodiment, the percentage of energy savings
`is determined as follows. A conditioned enclosure is being
`
`8
`
`

`

`US 6,478,233 B1
`
`7
`maintained at a dry-bulb temperature T1 which is higher than
`the outside temperature To, to which the conditioned enclo-
`sure is exposed. The rate of heat loss from inside to the
`outside is given by:
`
`Q1=UA(T1—To)
`Where:
`
`(7)
`
`Q1 is the rate of heat loss from inside to outside when the
`indoor dry-bulb temperature is T1
`U is overall U-value of the structure exposed to the
`outside temperature TO
`A is the area of the structure exposed to the outside
`temperature To.
`The inside/enclosure temperature T1 and the outside tem-
`perature T0 are provided by operatively attached sensors.
`The U-value and the area of the structure exposed to the
`outside temperature may be entered into the thermostat.
`When the thermal comfort controller used for maintaining
`the enclosure dry bulb temperature T1 is reset to a new
`energy saving value T2, which is lower than T1 in the heating
`mode, then the new and reduced rate of heat loss from the
`inside to the outside is given by:
`
`10
`
`15
`
`20
`
`Q2=UA(T2—To)
`
`(8)
`
`25
`
`Where Q2 is the rate of heat loss from inside to outside,
`when the inside dry-bulb temperature is T2.
`Because T2 is less than T1 and all other parameters are the
`same, the fraction of energy savings probable by maintain-
`ing the enclosure at an energy saving temperature T2 lower
`than temperature T1 is given by:
`
`(9)
`
`30
`
`35
`
`Substituting equations (7) and (8)
`respectively,
`
`for Q1 and Q2,
`
`
`1_ g: _ UA(T2-To)=1_ (Tz-To)
`UA(T1 - T0)
`Q1
`(T1 - To)
`
`1_ g 2 (T1 —T2)
`(T1 — To)
`Q1
`
`r
`
`,
`
`40
`
`(10)
`
`Therefore, if the conditioned enclosure is always main-
`tained at a comfort dry-bulb temperature of T1, then for any
`fixed or variable outdoor temperature To, the occupant can
`determine the potential energy savings, if the enclosure were
`permitted to operate at an energy savings dry-bulb tempera-
`ture T2 by using equation (10):
`
`
`(T1 - T2)
`(T1 — To)
`
`to obtain the fraction of energy savings, or using:
`
`
`(T1 — T2)
`(T1 — To)
`
`X100
`
`(11)
`
`12
`
`(
`
`)
`
`to give the percentage of potential energy savings.
`The percentage of potential energy savings may be dis-
`closed to the occupant by graphical display on the
`thermostat, printed out on an attachable printer, or the like.
`Additionally, the energy savings estimator may be used for
`diagnostic functions. The occupant may maintain a running
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`estimate of potential energy uses and/or savings to deter-
`mine the energy efficiency of the enclosure. The running
`estimate may indicate something is wrong with the
`enclosure, such as a leak in the building structure, or the like.
`The diagnostic functions, as well as the energy savings
`estimation, may be transferred or maintained by remote
`access with a standalone PC or PDA.
`Alternatively, where a time varying profile is available for
`any of the dry-bulb temperatures T1, T2, and T0, the calcu-
`lations could be done for each time step in the setup/setback
`schedule, and then arithmetically manipulated (e.g.
`integrated, averaged, or the like) to obtain the average
`energy savings.
`Additionally, the energy savings estimation may be done
`for a thermostat that does not have AIR algorithms.
`Although the invention has been described in terms of
`particular embodiments and applications one of ordinary
`skill
`in the art,
`in light of this teaching, can generate
`additional embodiments and modifications without depart-
`ing from the spirit of or exceeding the scope of the claimed
`invention. Accordingly,
`it
`is to be understood that
`the
`drawings and descriptions herein are proper by way of
`example to facilitate comprehension of the invention and
`should not be construed to limit the scope thereof.
`What is claimed is:
`
`1. An apparatus for cooperating with a thermal comfort
`controller having an indoor temperature sensor providing an
`indoor temperature signal encoding an indoor dry-bulb
`temperature, and which controls the operation of a climate
`control system to maintain an indoor temperature based
`upon a preprogrammed setup/setback schedule, the appara-
`tus for further providing an accurate estimate of energy
`savings, said apparatus comprising:
`an outdoor temperature sensor providing an outdoor tem-
`perature signal encoding an outdoor dry-bulb tempera-
`ture; and
`a calculator receiving an indoor temperature signal from
`the indoor temperature sensor which encodes the
`indoor temperature and the outdoor temperature signal,
`the preprogrammed setup/setback schedule from a ther-
`mal comfort controller memory, and a second indoor
`temperature set point
`from the thermal comfort
`controller, for computing a potential energy savings if
`the thermal comfort controller uses the second indoor
`temperature.
`2. The apparatus of claim 1, wherein the second indoor
`temperature is entered at the thermal comfort controller.
`3. The apparatus of claim 1, wherein the climate control
`system is any one of the group consisting of a furnace, air
`conditioner, heat pump, and fan coil unit.
`4. An apparatus for cooperating with a thermal comfort
`controller having an indoor temperature sensor, a user
`display, and which controls the operation of a climate
`control system to maintain an indoor temperature based
`upon a preprogrammed setup/setback schedule, the appara-
`tus for further providing an accurate estimate of energy
`savings, said apparatus comprising:
`an outdoor temperature sensor providing an outdoor tem-
`perature signal encoding an outdoor temperature;
`a calculator receiving an indoor temperature signal from
`the indoor temperature sensor which encodes the
`indoor temperature and the outdoor temperature signal,
`the preprogrammed setup/setback schedule from a ther-
`mal comfort controller memory, and another setup/
`setback schedule from the thermal comfort controller,
`wherein both setup/setback schedules comprise at least
`one indoor temperature set point, for computing an
`
`9
`
`

`

`US 6,478,233 B1
`
`9
`amount of energy savings if the thermal comfort con-
`troller uses the said another setup/setback schedule;
`wherein the amount of energy savings is determined by:
`determining the amount of energy required to maintain
`the enclosure at said at least one indoor temperature
`set point for both setup/setback schedules;
`determining the amount of energy required to recover
`from an energy savings set point temperature to the
`sensed indoor temperature;
`determining the amount of energy required to recover
`from an energy savings set point temperature to said
`at least one indoor temperature set point of said
`another setup/setback schedule; and
`comparing the amount of energy required to maintain
`the enclosure at both setup/setback schedules, and
`the amount of energy required to recover from an
`energy savings set point temperature to the sensed
`indoor temperature and to said at least one indoor
`temperature set point in said another setup/setback
`schedule; and
`wherein the amount of energy savings is displayed on the
`thermal comfort controller display.
`5. An apparatus for cooperating with a thermal comfort
`controller having an indoor temperature sensor, a user
`display, and which controls the operation of a climate
`control system to maintain an indoor temperature based
`upon a preprogrammed setup/setback schedule, the appara-
`tus for further providing an accurate estimate of energy
`savings, said apparatus comprising:
`an outdoor temperature sensor providing an outdoor tem-
`perature signal encoding an outdoor dry-bulb tempera-
`ture;
`
`a calculator receiving an indoor temperature signal from
`the indoor temperature sensor which encodes the
`indoor temperature and the outdoor temperature signal,
`the preprogrammed setup/setback schedule from a ther-
`mal comfort controller memory, and a second indoor
`temperature from the thermal comfort controller, for
`computing a percentage of potential energy savings if
`the thermal comfort controller uses the second indoor
`temperature;
`wherein the percentage energy savings is determined by a
`first value determined by the first
`indoor dry-bulb
`temperature minus the second indoor temperature, the
`first value divided by a second value determined by the
`first indoor dry-bulb temperature minus the outdoor
`dry-bulb temperature, and the resulting fraction multi-
`plied by 100;
`and wherein the percentage of energy savings is displayed
`on the thermal comfort controller display.
`6. A thermal comfort controller, including:
`an outdoor temperature sensor providing an outdoor tem-
`perature signal encoding an outdoor dry-bulb tempera-
`ture;
`
`an indoor temperature sensor providing an indoor tem-
`perature signal encoding an indoor dry-bulb tempera-
`ture value;
`a memory storing a preprogrammed setup/setback sched-
`ule and a new indoor temperature set point entered into
`said thermal comfort controller; and
`
`a calculator receiving the indoor and outdoor temperature
`signals, the preprogrammed setup/setback schedule and
`entered new indoor temperature set point for computing
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`10
`
`10
`a percentage of potential energy savings using the
`second indoor temperature.
`7. A thermostat comprising:
`an outdoor temperature sensor providing an outdoor tem-
`perature signal encoding an outdoor temperature;
`an indoor temperature sensor providing an indoor air
`temperature signal encoding an indoor temperature
`value; and
`a calculator receiving the indoor and outdoor air tempera-
`ture signals, an entered preprogrammed setup/setback
`schedule and an entered indoor temperature, for com-
`puting a potential energy savings using the entered
`indoor temperature.
`8. The thermostat of claim 7, wherein the preprogrammed
`setup/setback schedule and entered indoor temperature are
`stored in a memory in the thermostat.
`9. The thermostat of claim 8, wherein the entered indoor
`temperature is input into the thermostat by a user.
`10. The thermostat of claim 7, further comprising a
`display for presentation of the computed potential energy
`savings.
`11. The apparatus of claim 7, wherein the thermostat is
`operatively attached to any one of the group consisting of a
`furnace, air conditioner, heat pump, and fan coil unit.
`12. A method of estimating the amount energy saved by
`a modification of a setup/setback schedule of a thermostat
`controlling the temperature within a structure, comprising:
`providing a preprogrammed setup/setback schedule;
`sensing a indoor temperature;
`sensing an o

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