Patent Publication Number: US-9429334-B2

Title: HVAC personal comfort control

Description:
TECHNICAL FIELD 
     This application is directed, in general, to climate control, and, more specifically, to climate control systems and methods of operating such systems. 
     BACKGROUND 
     Climate control systems may take different forms depending on the application. In a residential or commercial building, for example, typically a heating, ventilating and air conditioning (HVAC) system is used to heat and/or cool the air within the building. In automobiles, cooling may be provided by an engine-driven compressor, and heating may be provided by a heat exchanger that warms the passenger cabin with engine-warmed coolant. In either case, climate control may be provided by a controller that modulates the duty cycle of the cool air source and/or the warm air source. In some cases, the controller may also control the humidity in the conditioned space. The comfort perceived by an occupant of the conditioned space is typically a function of both an absolute temperature (e.g. a dry-bulb temperature) and the relative humidity. 
     SUMMARY 
     One aspect provides a climate control system that includes a cooling source and/or a heating source, and a controller. The cooling and/or heating sources are configured to respectively cool and heat an enclosed space. The controller is configured to receive an apparent temperature set point. The controller is further configured to operate the cooling and/or heating sources to maintain an absolute air temperature within the enclosed space that is different from the apparent temperature set point. 
     Another aspect provides a method of manufacturing an HVAC system. The method includes in one step configuring a cooling source and/or a heating source to respectively cool and heat an enclosed space. In another step a controller is configured to receive an apparent temperature set point and to operate the cooling and/or heating sources to maintain an absolute air temperature within the enclosed space that is different from the apparent temperature set point. 
     Yet another aspect provides a climate control system. The system includes a cooling source and/or a heating source, and a controller. The cooling and/or heating sources are configured to respectively heat and cool an enclosed space. The controller is configured to display in lieu of a numerical value a non-alphanumeric icon representative of an apparent temperature set point. The controller is further configured to operate the cooling and/or heating sources to maintain air within the enclosed space at the apparent temperature set point. 
    
    
     
       BRIEF DESCRIPTION 
       Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates a climate control system according to one embodiment, including a control layer of a user interface (controller) configured to operate the system to maintain an apparent temperature; 
         FIG. 2  illustrates an embodiment of a physical layer of the user interface of  FIG. 1 ; 
         FIG. 3  is a graphical representation according to one embodiment of a range of absolute temperature and relative humidity that provides a comfortable ambient to a building occupant; 
         FIGS. 4A and 4B  illustrate examples of a user interface display during operation of the system of  FIG. 1  to transition from one apparent temperature set point to another apparent temperature set point; 
         FIG. 5  presents a method of operating the system of  FIG. 1  according to one embodiment; 
         FIGS. 6 and 7  illustrate example displays of the user interface display in which a selected apparent temperature is represented by a non-alphanumeric icon; and 
         FIG. 8  illustrates a method of manufacturing a climate control system in one embodiment, e.g. the system of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     In the following discussion and in the claims, the following terms have following associated meanings: 
     Relative humidity (RH): the ratio of the partial pressure of water vapor in the air to the saturation vapor pressure of water vapor at the pressure and temperature of the air. 
     Absolute temperature (T a ): a measure of the temperature of air without regard to the relative humidity thereof. As an example, a dry-bulb thermometer provides a measure of absolute temperature. 
     Apparent temperature (AT): a value that describes human physiological perception of comfort in a conditioned (heated and/or cooled) space, the value taking into account both T a  and RH. 
     Depending on the RH, heat loss can cause a person to feel warmer or colder than the absolute temperature alone would suggest. Thus, apparent temperature is sometimes referred to as a “feels like” temperature, may be equivalently referred to herein without loss of generality. However, some operators of a climate control system, e.g. homeowners, may not have an interest or the ability to easily determine a combination of RH and absolute temperature to provide a desired level of personal comfort. 
     The inventors provide herein a new paradigm for controlling a climate control system to maintain a desired personal comfort level. Rather than require the individual to maintain personal comfort by independently adjusting multiple environmental parameters, e.g. absolute temperature and humidity, the climate control system controls such parameters to maintain a selected apparent temperature. The system determines a suitable combination of absolute temperature and/or RH and controls system components as necessary to achieve the desired combination. This control may be transparent to the user, who as mentioned previously may be uninterested in the particular combination of absolute temperature and humidity that results in the desired comfort level. 
       FIG. 1  illustrates a climate control system  100  according to an illustrative nonlimiting embodiment. The system  100  is described as an HVAC system associated with a residential building, without limitation thereto. Those skilled in the pertinent art are able to apply the principles disclosed herein to other climate control systems, e.g. commercial HVAC systems, rooftop HVAC systems and automotive climate control systems. 
     The system  100  includes a controller  110 , an outdoor unit (OU)  120  and an indoor unit (IU)  130 . The controller  110  may be referred to synonymously herein as a user interface (UI)  110 . The controller  110  is configured to control the OU  120  and the IU  130 , and may be configured to appear similar to a conventional wall-mounted thermostat. See, e.g. U.S. Patent Application No. 2010/0101854, incorporated herein by reference in its entirety. The controller  110  communicates via a bidirectional communication bus  140  with the OU  120 , IU  130 , and other components as described further below. 
     The communication bus  140  may be any suitable wired or wireless network. In some embodiments, the network is an RSBus network as described in U.S. Patent Application No. 2010/0106320 (the &#39;320 application), incorporated herein by reference in its entirety. Such a system provides a protocol for addressed communication between networked devices. In other embodiments the bus  140  is a 4-wire system such as an RYWG 24-volt control system. In embodiments using a heat pump system, the bus  140  may be, e.g. a 7-wire control system. 
     The OU  120  and the IU  130  may be conventional. The OU  120  includes a compressor  120 - 1  and a condenser (not shown). The IU  130  includes an evaporator  130 - 1  and a furnace  130 - 2 . The compressor  120 - 1  and the evaporator  130 - 1  are configured to cool air passing through the IU  130 , thereby operating as a cooling source. The furnace  130 - 2  is configured to warm air passing through the IU  130 , thereby operating as a heating source. The IU  130  may thereby heat and/or cool air enclosed within the associated building. 
     The controller  110  is configured to receive an apparent temperature set point and to operate the compressor  120 - 1  and the furnace  130 - 2  to maintain the set point. Maintaining the set point includes at least actively controlling an absolute temperature of the indoor space, and in some embodiments also includes actively controlling the RH of the indoor space. 
     The system  100  may include a humidifier  160  and/or a dehumidifier  170 . The controller  110  may control the humidifier  160  and/or the dehumidifier  170  as described below to maintain a selected RH within the conditioned space. In other embodiments, the evaporator  130 - 1  may provide dehumidification, e.g. by undercooling. Such dehumidification may include, e.g. reducing airflow over the evaporator  130 - 1  to increase the residence time of the air in contact with the evaporator coils. In some embodiments the humidifier  160  may be omitted, such as when natural sources of humidity provide sufficient moisture to the enclosed space of the building. In such embodiments the controller  130  may select an absolute temperature that provides a desired apparent temperature with the naturally generated humidity level. 
     The controller  110  receives environmental data from a comfort sensor (CS)  150 . The CS  150  includes a temperature sensor  150 - 1  and a relative humidity (RH) sensor  150 - 2 . While shown as collocated in the figure, the sensors  150 - 1 ,  150 - 2  may be spatially separated, may be enclosed in separate enclosures, and may be independently addressed via the communication bus  140 . The temperature sensor  150 - 1  senses the absolute temperature of the air in the enclosed space conditioned by the system  100 . The RH sensor  150 - 2  senses the RH of the air. In some embodiments the sensors  150 - 1  and  150 - 2  report the temperature and RH to the controller  110  via the bus  140 , e.g. upon receiving a request from the controller  110 . In other embodiments the sensors  150 - 1 ,  150 - 2  are collocated with the controller  110  and bypass the bus  140  to communicate directly with the controller  110 . 
     The comfort sensor  150  may also in some embodiments include an airspeed sensor  150 - 3  and a radiant energy sensor  150 - 4 . These sensors may be used in some embodiments, described below, to enhance the capability of the comfort sensor  150  to report various environmental conditions that may affect the perceived comfort of an occupant. 
     The controller  110  is capable of executing various control and computational algorithms. The controller  110  in  FIG. 1  is described by a control layer. As described below, the controller  110  may include a microcontroller and memory to implement the control layer for such operation. The control layer includes control blocks as follows. A user input block  110 - 1  receives and parses input from, e.g. a keypad or touch screen. Among various control inputs that may be provided to the controller  110  via the user input block  110 - 1  is an apparent temperature set point. A display control block  110 - 2  formats data, e.g. an apparent temperature, for presentation to an operator. A cooling/heating control block  110 - 3  provides control of the OU  120  and the IU  130  to cool or heat the enclosed space as described below. A humidity control block  110 - 4  controls operation of the humidifier  160  and the dehumidifier  170  to maintain an RH of the enclosed space. An apparent temperature control block  110 - 6  coordinates operation of the cooling/heating block control  110 - 3  and the humidity control block  110 - 4  to maintain the apparent temperature set point. This aspect is described in detail below. 
     Various sources may dynamically contribute to the moisture within the conditioned space. In a humid location, for instance, moisture from outside air may intrude into the conditioned space. Conversely, moisture from the conditioned space may be lost to the environment in an arid location. Also, the occupants of a building, appliances and activities such as cooking may contribute significantly to both the absolute temperature and humidity of the conditioned space. To effectively maintain a personal comfort level, the climate control system  100  accommodates such heat and moisture variations by actively adding or removing heat and/or moisture to the conditioned space as necessary to maintain desired absolute temperature and RH set points. Unlike a conventional system, which may for example control RH to a specific value, the system  100  may allow the absolute temperature and RH to change while maintaining the apparent temperature set point. This approach may reduce over-controlling the absolute temperature and RH, and reduce operating costs by avoiding, e.g. unnecessary dehumidification. 
       FIG. 2  illustrates a physical layer of the controller  110  in one illustrative and nonlimiting embodiment. The controller  110  includes a processor  210  and an instruction memory  220 . The processor  210  may be any conventional or unconventional type of processor, including, e.g. a microprocessor, a microcontroller or a state machine, and may include any combination of discrete logic, analog components and passive components configured to provide or support the control functions described herein. The instruction memory  220  may be any type of volatile or nonvolatile memory capable of storing instructions to support the control functions implemented by the controller  210 . Examples include without limitation static RAM, dynamic RAM, flash memory and programmable read-only memory (PROM). While the controller  210  and the memory  220  are shown as separate components, they may be portions of a single integrated device. 
     A touch screen  230  provides input to and receives output from the controller  210 . An operator may, e.g. enter a desired apparent temperature set point to the controller  110  via the touch screen  230 . The processor  210  may display on the touch screen  230  a current apparent temperature set point and/or a current apparent temperature as determined from the measured absolute temperature and the RH. In other embodiments, the display and input functions of the touch screen are respectively provided instead by a separate keypad and screen. 
     A network interface  240  provides an electrical interface between the processor  210  and the communication bus  140 . The interface  240  may include any combination of analog, digital, discrete and/or integrated components to provide interfacing functions. Without limitation, one embodiment of the network interface is described in the &#39;320 application. 
     A memory  250  may include tabular data associating a selected apparent temperature with one or more combinations of an absolute temperature and an RH level, as described further below. The memory  250  is not limited to any particular type, but may be, e.g. a PROM. While shown as a separate component, the memory  250  may be a portion of the memory space provided by the instruction memory  220 , or may be embedded within the processor  210 . 
       FIG. 3  presents an illustrative and nonlimiting graphical representation of one scheme for relating perceived comfort to absolute temperature and RH. This scheme is described in, e.g. in ASHRAE STD 55 §5.2, incorporated herein by reference. Two shaded quadrilateral areas  310 ,  320  represent ranges of absolute temperature and RH that are associated with occupant comfort of a conditioned space. The area  310  represents the case of such persons wearing clothing with an effective insulation value of 1.0 clo. The area  320  represents the case of the persons wearing clothing with an effective insulation value of 0.5 clo. Within each shaded area  310 ,  320  about 90% of persons are expected to report feeling neither too hot nor too cool (neutral) on a seven-point thermal sensation scale. 
     Either or both of the areas  310  and  320  may be represented in a format readable by the processor  210  in various embodiments described herein. For example, the area  310  may be described by the absolute temperature and RH at each corner of the quadrilateral corresponding to the area  310 . Alternatively or in combination, ranges of comfortable absolute temperatures on each RH curve that intersects the area  310  may be determined and tabulated. If desired, a separate tabulation may be determined for each of the areas  310 ,  320 . In some embodiments a tabulation associated with a lower clothing insulation value, e.g. the area  320 , is used in summer months, while a tabulation associated with a higher clothing insulation value, e.g. the area  310 , is used in winter months. 
     In some embodiments, an equation may be determined that predicts a perceived temperature, e.g. the apparent temperature T a . For example, Equation 1 below, attributed to Steadman (1994), predicts the apparent temperature AT (in ° C.) perceived by an individual as a function of absolute temperature (in ° C.) and RH. (See, e.g. www.bom.gov.au/info/thermal_stress.)
 
AT= T   a +0.33·(RH/100·6.105*exp(17.27· T   a /(237.7− T   a )))−4.00  (1)
 
     In some embodiments the parameters of Eq. 1 or a similar equation may be embedded in operating instructions of the processor  210 , enabling the processor  210  to directly compute a value of the apparent temperature from the measured T a  and RH. In some embodiments Eq. 1 or a similar equation may be used to generate tabular data that are then stored in the memory  250 . For example, Table I presents an illustrative and nonlimiting example of such tabular temperature data, determined from Eq. 1 for a range of absolute temperature consistent with expected operation of the system  100  in some embodiments. 
     
       
         
           
               
               
             
               
                   
                 TABLE I 
               
             
            
               
                   
                   
               
               
                   
                 Absolute Temperature 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 RH 
                 68 
                 69 
                 70 
                 71 
                 72 
                 73 
                 74 
                 75 
                 76 
                 77 
                 78 
                 79 
                 80 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 0 
                 61 
                 62 
                 63 
                 64 
                 65 
                 66 
                 67 
                 68 
                 69 
                 70 
                 71 
                 72 
                 73 
               
               
                 5 
                 61 
                 63 
                 64 
                 65 
                 66 
                 67 
                 68 
                 69 
                 70 
                 71 
                 72 
                 73 
                 74 
               
               
                 10 
                 62 
                 63 
                 64 
                 65 
                 66 
                 67 
                 68 
                 70 
                 71 
                 72 
                 73 
                 74 
                 75 
               
               
                 15 
                 63 
                 64 
                 65 
                 66 
                 67 
                 68 
                 69 
                 70 
                 72 
                 73 
                 74 
                 75 
                 76 
               
               
                 20 
                 64 
                 65 
                 66 
                 67 
                 68 
                 69 
                 70 
                 71 
                 72 
                 74 
                 75 
                 76 
                 77 
               
               
                 25 
                 64 
                 65 
                 67 
                 68 
                 69 
                 70 
                 71 
                 72 
                 73 
                 74 
                 76 
                 77 
                 78 
               
               
                 30 
                 65 
                 66 
                 67 
                 68 
                 70 
                 71 
                 72 
                 73 
                 74 
                 75 
                 77 
                 78 
                 79 
               
               
                 35 
                 66 
                 67 
                 68 
                 69 
                 70 
                 72 
                 73 
                 74 
                 75 
                 76 
                 78 
                 79 
                 80 
               
               
                 40 
                 66 
                 68 
                 69 
                 70 
                 71 
                 72 
                 74 
                 75 
                 76 
                 77 
                 79 
                 80 
                 81 
               
               
                 45 
                 67 
                 68 
                 69 
                 71 
                 72 
                 73 
                 74 
                 76 
                 77 
                 78 
                 80 
                 81 
                 82 
               
               
                 50 
                 68 
                 69 
                 70 
                 71 
                 73 
                 74 
                 75 
                 77 
                 78 
                 79 
                 80 
                 82 
                 83 
               
               
                 55 
                 68 
                 70 
                 71 
                 72 
                 74 
                 75 
                 76 
                 77 
                 79 
                 80 
                 81 
                 83 
                 84 
               
               
                 60 
                 69 
                 70 
                 72 
                 73 
                 74 
                 76 
                 77 
                 78 
                 80 
                 81 
                 82 
                 84 
                 85 
               
               
                 65 
                 70 
                 71 
                 72 
                 74 
                 75 
                 76 
                 78 
                 79 
                 81 
                 82 
                 83 
                 85 
                 86 
               
               
                 70 
                 70 
                 72 
                 73 
                 75 
                 76 
                 77 
                 79 
                 80 
                 82 
                 83 
                 84 
                 86 
                 87 
               
               
                 75 
                 71 
                 73 
                 74 
                 75 
                 77 
                 78 
                 80 
                 81 
                 82 
                 84 
                 85 
                 87 
                 88 
               
               
                 80 
                 72 
                 73 
                 75 
                 76 
                 77 
                 79 
                 80 
                 82 
                 83 
                 85 
                 86 
                 88 
                 89 
               
               
                 85 
                 73 
                 74 
                 75 
                 77 
                 78 
                 80 
                 81 
                 83 
                 84 
                 86 
                 87 
                 89 
                 90 
               
               
                 90 
                 73 
                 75 
                 76 
                 78 
                 79 
                 81 
                 82 
                 84 
                 85 
                 87 
                 88 
                 90 
                 91 
               
               
                 95 
                 74 
                 75 
                 77 
                 78 
                 80 
                 81 
                 83 
                 84 
                 86 
                 88 
                 89 
                 91 
                 92 
               
               
                 100 
                 75 
                 76 
                 78 
                 79 
                 81 
                 82 
                 84 
                 85 
                 87 
                 89 
                 90 
                 92 
                 94 
               
               
                   
               
            
           
         
       
     
     The personal comfort model may also in some embodiments include other comfort characteristics. For example, as described above the comfort sensor  150  may include the airspeed sensor  150 - 3  and the radiant energy sensor  150 - 4 . ASHRAE STD 55 describes inclusion of the radiant energy (RE) and airspeed (AS) in a model of apparent temperature. Such a model may be generally expressed as
 
AT= f ( T   a ,RH,RE,AS).
 
For example, radiant energy from, e.g. windows or appliances may not be perceived by the temperature sensor  150 - 1 , but heat absorbed by an occupant&#39;s body may cause the occupant to perceive a higher temperature than would otherwise be the case. Moreover, moving air may cool the occupant, lowering the perceived temperature. The airspeed sensor  150 - 3  and the radiant energy sensor  150 - 4  provide a measure of these comfort characteristics to the user interface  110 . In some embodiments the airspeed sensor  150 - 3  and/or the radiant energy sensor  150 - 4  are portable units that may be collocated with the occupant to accurately reflect the microenvironment the occupant experiences. In some embodiments the airspeed sensor  150 - 3  and/or the radiant energy sensor  150 - 4  are wirelessly connected to the user interface  110  via a wireless extension of the communication bus  140  to enable greater portability.
 
       FIG. 4A  shows an illustrative nonlimiting embodiment of a display configuration of the touch screen  230 . The touch screen  230  displays an apparent temperature under the text “Currently feels like”, in this example 72° C. (˜22.2° C.). Absent from the screen is any display of the current absolute temperature or RH. While the scope of the claims includes embodiments that include one or both of the absolute temperature and RH, the embodiment of  FIG. 4A  advantageously presents an uncluttered display of the apparent (“feels like”) temperature, which in many cases is the parameter the operator most cares about. An up arrow  310  allows an operator to increment the apparent temperature set point of the system  100 , while a down arrow  420  allows the operator to decrement the apparent temperature set point. In  FIG. 4A  the down arrow  420  includes an unreferenced outline, indicating that this arrow has been recently selected to effect a change of the system  100  control set point.  FIG. 4B  illustrates the touch screen  230  after the indicated apparent temperature has stabilized at the selected value, e.g. 71° F. 
       FIG. 5  presents a method  500  of operating the system  100  in an illustrative nonlimiting embodiment. The method  500  is described with reference to the system  100 , without limitation thereto. The steps of the method  500  may be performed in another order than that shown, and the method may include steps other than the illustrated steps. The method  500  is also described with reference to  FIGS. 4A and 4B  to illustrate a nonlimiting example. In  FIG. 4A  the operator has recently decremented the apparent temperature, as indicated by the box drawn around the down arrow  420 . 
     The method  500  begins with a step  501 , such as a subroutine entry point called upon the activation of the down arrow  420 . In a step  510  the processor  210  receives the apparent temperature set point entry from the touch screen  230 . In a step  520  the controller  130  determines one or more combinations of actual temperature and RH that result in an apparent temperature about equal to the apparent temperature set point. The method  500  then advances to a decisional step  530 . 
     In the step  530  the controller  110  determines if there is at least one solution within a preferred RH range, e.g. between about 40% and about 60%. The controller  110  may be configured to allow the operator to input the preferred RH range via a setup screen, or this range may be programmed by the manufacturer. If the controller  110  determines there is at least one such solution within the preferred RH range the method  500  advances to a decisional step  540 . In the step  540  the controller  110  determines if there are multiple solutions in the preferred RH range. It is apparent by inspection of Table I that in some cases multiple combinations of T a  and RH may produce a same apparent temperature. If there are multiple solutions the method  500  advances to a step  550 . In the step  550  the controller  110  selects the solution that has an RH that is closest to the current RH as reported by the RH sensor  150 - 2 . The method  500  then advances to a step  560  in which the controller  110  controls for the selected T a  and RH. 
     If in the step  530  the controller  110  determines that there is not at least one solution within the preferred RH range, the controller  110  selects the solution with an RH closest to the upper or lower limit of the preferred range, e.g. 60% or 40%. For example, if the RH prior to the new apparent temperature set point is less than 40%, the controller may select a combination of T a  and RH that results in the desired apparent temperature while providing an RH as close to 40% as possible. The method then advances to the step  560  and controls for the selected solution. 
     If in the step  540  the controller determines there are not multiple solutions in the preferred RH range, the method  500  advances to a step  580 . In the step  580  the controller selects the unique solution within the preferred RH range. The method  500  advances to the step  560  and controls for the selected solution. The method ends with a return step  599  that returns, e.g. to a calling master control routine. 
     Returning to the example of the apparent temperature set point change in  FIGS. 4A and 4B , two cases are described. For the purpose of discussion, it is assumed that the apparent temperature set point is initially 72° F. (˜22.2° C.), the new apparent temperature set point is 71° C. (˜21.7° C.), and the preferred RH range is about 40% to about 60%. 
     In a first illustrated case, the T a  and RH are initially 73° F. (˜22.8° C.) and 35%, respectively prior to the change of apparent temperature. Referring to Table I, two possible combinations of T a  and RH that result in an apparent temperature of 71° F. are 72° F./40% and 74° F. (23.3° C.)/25%. Referring to the method  500  without limitation, the former combination is selected, because the RH is within the preferred range of 40%-60% RH. 
     In a second illustrative case, the RH at the initial absolute temperature set point of 72° F. is about 60%. Again referring to Table I, the absolute temperature that corresponds to an apparent temperature T a  of 72° F. at 60% RH is about 70° F. At the new apparent temperature set point of 71° F. ( FIG. 4B ) the absolute temperature may be about 69° F. at about 65% RH, or about 71° F. at about 45-50% RH. In this case the method  500  will select the solution at 71° F. and 45-50% RH, since the RH is in the preferred range. 
     In both of these illustrative cases, the controller  110  operates the system  100  to maintain an apparent temperature of the conditioned space at 71° F. after the set point is reduced. However, the absolute temperature may differ from the displayed apparent temperature set point. In the first case, the displayed apparent temperature set point is 71° F., while the absolute temperature is 72° F. This feature is contrary to known climate control methods and systems, for which the system controller operates the climate control system to maintain an absolute temperature that is equal to a displayed temperature set point. 
       FIG. 6  shows an illustrative and nonlimiting embodiment of the display  230  in which the numeric display of T a  is replaced with a non-alphanumeric representation, or icon,  610 . The icon  610  is shown without limitation as a figure representing a house. The icon  610  may conveniently represent a comfort setting appropriate for times the conditioned space is occupied. Because the apparent temperature displayed, e.g. in  FIG. 4A , does not necessarily reflect the absolute temperature of the conditioned space, the numeric display of  FIG. 4A  may be replaced with the more symbolic representation of the apparent temperature provided by the icon  610  without significant loss of information. For many users, an abstract representation may be sufficient or even desirable, as many users are interested in perceived comfort rather than the particular combination of T a  and RH selected by the controller  110 . The icon  610  may therefore be designed to provide other information that may be more immediately relevant to the operator, such as which of several programmable time-of-day set points the controller  130  is using. 
     As an example,  FIG. 7  illustrates another display  700 , referred to without limitation as “FeelsLike™ Comfort Control Programming”. In this embodiment programmable time periods during a representative week may be programmed for weekdays (Monday-Friday) and the weekend (Saturday-Sunday). Weekdays and weekends are divided into four time ranges, and the apparent temperature may be independently programmed for each time range. Without limitation, three icons are shown in addition to the home icon  610 . A “wake time” icon  710  may represent an apparent temperature that a user selects for a time the user may arise in the morning. An “away” icon  720  may represent an apparent temperature selected by the user for use when the building is unoccupied. And a “bedtime” icon  730  may represent the apparent temperature selected by the user for sleeping hours. Of course other icons, time periods, and number of time periods may be selected and remain within the scope of the disclosure. 
     In some embodiments (not shown), the space conditioned by the system  100  is one of a plurality of zones in a conditioned building. For example, the controller  110  may be located in a first zone that includes bedrooms of a home. An occupant of a bedroom may select an apparent temperature that is subjectively more comfortable for sleeping via the controller  110  within that zone. The described capabilities of the system  100  allow the occupant to easily adjust the apparent temperature set point by numeric value or by symbolic icon for comfortable sleeping. An occupant of a second zone including, e.g. common areas of the home, may adjust the apparent temperature of the second zone independently of the first zone. Such control may be, e.g. via the controller  100  or a second controller. 
     Turning to  FIG. 8 , a method  800  is illustrated for manufacturing a climate control system in a nonlimiting illustrative embodiment. The method  800  is described without limitation with reference to features previously described with respect to the system  100 , e.g. in  FIGS. 1-8 . The steps of the method  800  may be performed in another order than the illustrated order, and in some embodiments may not be performed at all. 
     In a step  810  a cooling source and/or a heating source are configured to respectively cool and heat an enclosed space. In a step  820  a controller is configured to receive an apparent temperature set point. The controller is further configured to operate the cooling and/or heating sources to maintain an absolute air temperature with the enclosed space that is different from the apparent temperature set point. 
     In a step  830  the controller is further configured to maintain a relative humidity that, in combination with the absolute temperature, results in the apparent temperature. In a step  840  the controller is configured to maintain the relative humidity by undercooling the enclosed space. In a step  850  the controller is configured to maintain the relative humidity by operating a humidifier. 
     In a step  860  the controller is configured to display the apparent temperature set point. In a step  870  the controller is configured to display a non-alphanumeric icon representative of the apparent temperature set point. 
     In a step  880  the controller is configured to control the cooling and/or heating sources via a bidirectional communication bus. 
     In a step  890  the controller is configured to control both absolute temperature and relative humidity to maintain the apparent temperature. 
     Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.