GB2534553A

GB2534553A - Central heating system control units and methods of controlling a central heating system

Info

Publication number: GB2534553A
Application number: GB1500917.8A
Authority: GB
Inventors: Suyeon Kim; Parsons Matthew
Original assignee: EXERGY DEVICES Ltd
Current assignee: EXERGY DEVICES Ltd
Priority date: 2015-01-20
Filing date: 2015-01-20
Publication date: 2016-08-03
Anticipated expiration: 2035-01-20
Also published as: GB201500917D0; GB2534553B

Abstract

The invention relates to a control unit 12 for controlling a central heating system for heating a building. The central heating system includes a heat pump 10 that supplies hot water to radiators 11 for space heating. The control unit 12 stores a plurality of different time-varying setpoint temperature profiles. Each of the time-varying setpoint temperature profiles has an early morning section with a first average setpoint temperature, an evening section with a second average setpoint temperature that is higher than the first average setpoint temperature, and a daytime section that transitions between the early morning and evening sections. A user interface 18 is provided through which the user can select one of the time-varying setpoint temperature profiles as a baseline time-varying setpoint temperature profile. The control unit 12 is further adapted to use the baseline time-varying setpoint temperature profile to control the operation of the central heating system.

Description

TITLE

Central heating system control units and methods of controlling a central heating system

DESCRIPTION

Technical Field

The present invention relates to control units for central heating systems, and in particular to electronic control units that use a setpoint temperature to regulate the operation of the central heating system.

Background to the Invention

In order to ensure comfort for the occupants, a central heating system for a building typically has an electronic control unit that regulates the supply of heat energy into heat exchangers (e.g., radiators) that warm the air in rooms and the fabric and contents of the building. The regulation of the supply of heat energy is performed such that the temperature inside the building is maintained within a suitably narrow range such as 20°C to 21°C, as measured by one or more temperature sensors that provide temperature information to the control unit. The energy consumed to maintain this temperature is proportional to the difference between the internal temperature of the building and the external ambient temperature. The internal temperature that the control unit aims to maintain (referred to herein as the setpoint temperature) therefore has a critical effect on the energy required and cost to heat the building.

The setpoint temperature can typically be selected by the user. In many cases, the setpoint temperature will be selected using a user interface and will be constant throughout the day unless it is manually adjusted by the user. However, time-varying setpoint temperature profiles are also known, e.g., to take account of times when the building is likely to be unoccupied. EP 0444308 (Bunderus Heiztechnik GmbH) and US 5790437 (Watlow Electric) provide methods for a user to enter a daily profile (i.e., a series of setpoint temperatures that are applicable in sequence depending on the time of day). -1 -

In order to minimise energy consumption and cost, the setpoint temperature should be at the lowest level consistent with the comfort of the occupants. It is known that human perception of comfort within a building is dependent on multiple factors such as inter alit( metabolic rate, humidity, and clothing worn. It is also known that in a building such as a domestic residence where there is natural ventilation, and the occupants are able to adjust their clothing or open windows, a wider temperature range is acceptable for comfort, and that the temperature range is influenced by the climate external to the building. This kind of occupant environment permits what is known as adaptive comfort some aspects of which are embodied in standards such as ISO 7730 and EN 15251.

Weather forecast information provided to the control unit can be exploited using methods which are typically based on the physical properties of the building. For example, US 20120259470 (Nijhawan) discloses a method for acquiring weather forecast information and using it to predict the effect of prevailing weather on the building and from that prediction determine an adjustment to the setpoint temperature.

There is a need for an improved method and control unit that makes use of knowledge concerning adaptive comfort by using a time-varying setpoint temperature profile that takes account of ongoing variations in the parameters that affect comfort, such that energy consumption is minimised.

Summary of the Invention

The present invention provides a method of controlling a central heating system for heating a building, the method comprising the steps of providing a plurality of different time-varying setpoint temperature profiles (e.g., that have different overall average setpoint temperatures and/or different profile shapes), each of the time-varying setpoint temperature profiles having an early morning section with a first average setpoint temperature, an evening section with a second average setpoint temperature that is higher than the first average setpoint temperature, and a daytime section that transitions between the early morning and evening sections; -2 -a user selecting one of the time-varying setpoint temperature profiles as a baseline time-varying setpoint temperature profile; and using the baseline time-varying setpoint temperature profile to control the operation of the central heating system.

The method provides a practical way of implementing adaptive comfort, and is particularly applicable for a building that permits adaptive comfort such as a domestic residence. The method can be implemented by a control unit for the central heating system that uses the baseline time-varying setpoint temperature profile (or a modified baseline time-varying setpoint temperature profile -see below) to regulate the supply of heat energy (e.g., from a boiler or other heat source) into heat exchangers (e.g., radiators) in a known manner.

The different time-varying setpoint temperature profiles are preferably predetermined and provide different levels of comfort. Any suitable number of different time-varying setpoint temperature profiles can be provided, but between 3 and 6 might be typical.

Each time-varying setpoint temperature profile can include a set of setpoint temperatures, each setpoint temperature being associated with a respective time period. For example, each time-varying setpoint temperature profile can include a set of 24 setpoint temperatures where the first setpoint temperature is associated with the time period 00:00-00:59, the second setpoint temperature is associated with the time period 01:00-01:59, the third setpoint temperature is associated with the time period 02:00 to 02:59, and so on. It will be readily appreciated that each setpoint temperature is used by the control unit to regulate the supply of heat energy during the respective time period, unless modified or adjusted by ambient climate information -see below.

The early morning section can start at around 00:00 and can end during the morning, e.g., around 09:00. The evening section can start during the early evening, e.g., around 18:00, and can end at around 23:59.

The different setpoint temperature profiles can have different start and end times. -3 -

The first average setpoint temperature for the early morning section can be substantially constant. Put another way, the setpoint temperatures that define the early morning section of each time-varying setpoint temperature profile can be substantially the same.

The second average setpoint temperature for the evening section can be substantially constant. Put another way, the setpoint temperatures that define the evening section of each time-varying setpoint temperature profile can be substantially the same. The second average setpoint temperature can be between about 0.5°C and about 2.0°C higher than the first average setpoint temperature to take account of the fact that the human metabolic rate is normally lower in the evening when people are relaxing than it is earlier in the day when they are more likely to be physically active.

The setpoint temperatures that define the early morning and/or evening sections of each time-varying setpoint temperature profile do not have to be constant and can have any suitable profile. The 'average setpoint temperature' can be the arithmetic mean of the respective setpoint temperatures for the overall profile or section as appropriate. For example, the overall average setpoint temperature for a particular profile can be the sum of the individual setpoint temperatures divided by the number of setpoint temperatures that are used to define the profile.

The daytime section can have any suitable profile that transitions between the early morning and evening sections.

If the building is unoccupied it may be appropriate to set a much lower, fixed, setpoint temperature (e.g., I 4°C). Because the time-varying setpoint temperature profiles are intended to provide comfort for building occupants who are present and awake, it is expected that the control unit (or overall heating control system) will include a timer and/or occupancy detection unit that can control when the central heating system is operational, i.e., when the control unit should use the baseline (or modified baseline) time-varying setpoint temperature profile to regulate the supply of heat energy.

Alternatively the setpoint temperature can be switched to and from a lower, fixed, setpoint temperature to the time-varying setpoint temperature profile.

The method can further include the steps of: obtaining information indicative of the ambient climate external to the building; using the ambient climate information to modify the baseline time-varying setpoint temperature profile; and using the modified baseline time-varying setpoint temperature profile to control the operation of the central heating system (instead of the baseline time-varying setpoint temperature profile).

The information indicative of the ambient climate external to the building can include information about one or more weather-related parameters including inter alict temperature, wind speed and direction, insolation, precipitation, barometric pressure etc. Such ambient climate information can relate to the prevailing (or current) conditions or to future conditions, i.e., the information can optionally be predicted or forecast information. The ambient climate information can include a set of values for each weather-related parameter, each value being associated with a respective time period. Ambient climate information can be obtained from one or more external sensors or from a commercial weather forecast service/data provider such as the DataPoint service provided by the Meteorological Office. The ambient climate information can be provided over the Internet or any other suitable connection, including a wireless connection.

The ambient climate information can be used to appropriately modify or adjust the baseline lime-varying setpoint temperature profile to provide a minimum setpoint temperature that will maintain the user's comfort level by taking into account the human psychological, physiological, and behavioural responses to the prevailing external climate. The modification or adjustment to the baseline time-varying setpoint temperature profile can be determined using the following multi-term equation to reflect the simultaneous influence of multiple weather-related parameters on human comfort: -5 -A -k1P1 + k2P2 + k3P3 + .k"Pi, where A is the adjustment value, P/..P,, are the weather-related parameter values, and are the weighting factors expressing the influence of each weather-related parameter. The weighting factors are themselves can be dependent on the weather-related parameters through the application of threshold values for the weather-related parameters of the form: for Pi> vp, ki, -vk," otherwise lc, -0 This reflects the fact that weather-related parameters normally have a range of values over which no setpoint temperature adjustment is required, but when a value is outside this range an adjustment is needed that is proportional to the weather-related parameter. It will be readily appreciated that other ways of determining or calculating the modification or adjustment to the baseline time-varying setpoint temperature profile can be used.

A set of adjustment values can be determined, each value being associated with a respective time period and using information indicative of the ambient climate external to the building that is applicable for the same time period. The set of adjustment values can then be used to adjust the respective setpoint temperatures and hence modify the baseline time-varying setpoint temperature profile. For example, an adjustment value associated with the time period 10:00-10:59 determined using information relating to one or more weather-related parameters for the same time period can be used to modify the setpoint temperature associated with the time period 10:00-10:59, an adjustment value associated with the time period 11:00-11:59 determined using information relating to one or more weather-related parameters for the same time period can be used to modify the setpoint temperature associated with the time period 11:00-11:59, and so on. The setpoint temperatures can be increased or decreased by the respective adjustment values as appropriate. -6 -

The present invention can include a control unit (e.g., an electronic control unit) for controlling a central heating system using the method described above.

The present invention further provides an apparatus comprising: a control unit (e.g., an electronic control unit) for controlling a central heating system for heating a building, the control unit being adapted to store (e.g., in a memory) or access (e.g., from an external source) a plurality of different time-varying setpoint temperature profiles, each of the time-varying setpoint temperature profiles having an early morning section with a first average setpoint temperature, an evening section with a second average setpoint temperature that is higher than the first average setpoint temperature, and a daytime section that transitions between the early morning and evening sections; and a user interface through which the user can select one of the time-varying setpoint temperature profiles as a baseline time-varying setpoint temperature profile; wherein the control unit is further adapted to use the baseline time-varying setpoint temperature profile to control the operation of the central heating system.

The control unit can receive information indicative of the ambient climate external to the building. For example, the control unit can be connected to the Internet (optionally by means of a connected peripheral device such as a router) so that the information can be downloaded, or can include a communication unit that is capable of receiving the information from an external source. The control unit can be further adapted to use the ambient climate information to modify the baseline time-varying setpoint temperature profile, and to use the modified baseline time-varying setpoint temperature profile to control the operation of the central heating system.

The user interface can provide different options (e.g., comfort options) to the user, each option being selected using a button or switch on the user interface. Each option will correspond to a different time-varying setpoint temperature profile. The options can be presented as graphical indications or images that allow the user to select a desired comfort level. The user interface can be a portable electronic device (e.g., a tablet computer or smart phone) that can be wirelessly connected to the control unit (or to a -7 -connected peripheral device such as a router, for example) using a suitable wireless communication protocol. The control unit can also be connected to the Internet through the peripheral device. It will be readily appreciated that other user interfaces can be used.

During the periods of time when heating is demanded or needed (such periods optionally being set independently by means of a timer unit or when an unscheduled demand for heating is made, or when the building is occupied, for example), the control unit will control the operation of the central heating system with reference to the baseline (or modified baseline) time-varying setpoint temperature. For example, one or more temperature sensors can provide information to the control unit about the temperature inside the building. This measured temperature information can be compared against the applicable setpoint temperature, optionally as modified by an adjustment value. If the measured temperature is less than the applicable setpoint temperature, the control unit can demand heating from the boiler or other heat source. In other words, the control unit can control the ON/OFF operation of the boiler or other heat source that forms part of the central heating system.

The setpoint temperature is automatically varied depending on the time of day and the current state of weather-related parameters so that energy is saved and comfort is improved.

Drawings Figure I is a schematic diagram illustrating a central heating system including a control unit and user interface according to the present invention; Figure 2 is a graph showing a plurality of Lime-varying setpoint temperature profiles; Figure 3 is a schematic diagram showing a first user interface according to the present invention; Figure 4 is a schematic diagram showing a second user nterface according to the present invention; Figure 5 is a schematic diagram showing a first conventional user interface; and Figure 6 is a schematic diagram showing a second conventional user interface. -8 -

A central heating system 1 is shown in Figure 1 and include a heat pump 10 that heats a building by circulating hot water through radiators 11. A control unit 12 for the heat pump 10 is connected to a room temperature sensor 13. The control unit 12 regulates the generation of hot water by the heat pump 10 and the flow of hot water to the radiators 11 so that the room temperature as measured by the room temperature sensor 13 is as close as possible to an applicable setpoint temperature.

The control unit 12 is connected by an Ethernet cable 14 to a router 15 that is connected to the Internet 16 and equipped with a local WiFi® transmitter and receiver 17. The user can send instructions to the control unit 12 using a portable electronic device 18 (e.g., a tablet computer or smart phone) with a WiFi® transmitter and receiver 19. It will be readily appreciated that other communication protocols can also be used. The portable electronic device 18 connects to the router 15 using the WiFi® network. The control unit 12 runs software that includes a webserver which publishes web pages over the local WiFi network so that they can be displayed to the user on the portable electronic device 18. The portable electronic device 18 acts as a user interface that allows the user to select options for the control unit 12. Different user interfaces can also be used.

With reference to Figure 2, the control unit 12 stores four different time-varying daily setpoint temperature profiles (hereinafter referred to as 'daily profiles') 20a-20d. The daily profiles can be stored in a memory unit. Alternatively, the daily profiles can be stored at an external source and accessed by the control unit, e.g., using the router 15 to access the Internet 16. The daily profiles 20a-20d have different overall average setpoint temperatures and different profile shapes, e.g., different gradients. Each daily profile has an early morning section 21 with a first average setpoint temperature, an evening section 22 with a second average setpoint temperature that is higher than the first average setpoint temperature, and a daytime section 23 that transitions between the early morning and evening sections. The second average setpoint temperature is typically between about 0.5°C and about 2.0°C higher than the first average setpoint temperature to take account of the fact that the human metabolic rate is normally lower -9 -in the evening when people are relaxing than it is earlier in the day when they are more likely to be physically active. For each daily profile, the early morning section 21 starts at 0:00 and ends at 09:59, the evening section 22 starts at 18:00 and ends at 23:59. The daytime section 23 starts at 10:00 and ends at 17:59. But it will be readily appreciated by the skilled person that the daily profiles can have different start and end times. The daily profiles 20a-20d can also be specific to the days of the week. For example, the daily profiles 20a-20d shown in Figure 2 could be used on weekdays and a different set of four daily profiles could be used on weekends.

The first daily profile 20a has a first average setpoint temperature of 18.5°C that is applicable during the early morning section 21 and a second average setpoint temperature of 20°C that is applicable during the evening section 22. The daytime section 23 has a profile with a two-part gradient where the setpoint temperature increases from 18.5°C to 20°C as shown in Figure 2. The fourth daily profile 20d has a first average setpoint temperature of 21.5°C that is applicable during the early morning section 21 and a second average setpoint temperature of 22.5°C that is applicable during the evening section 22. The daytime section 23 has a profile with a one-part gradient where the setpoint temperature increases from 21.5°C to 22.5°C as shown in Figure 2. It can therefore be seen that the daily profiles 20a-20d provide increasing levels of comfort, with the first daily profile 20a having the lowest overall average setpoint temperature (and hence providing the lowest comfort level) and the fourth daily profile 20b having the highest overall average setpoint temperature (and hence providing the highest level of comfort). The first daily profile 20a might be suitable for a building with younger or more active occupants, or occupants that want to minimise heating costs, whereas the fourth daily profile 20d might be suitable for a building with older or less active occupants.

The published web page displaced on the portable electronic device 18 includes a set of four comfort options 24a-24d and 25a-25d as shown in Figures 3 and 4. A comfort level can be selected by the user, e.g., by pressing a button or switch on the portable electronic device 18 which would include a region of a touch-screen display. Each comfort option 24a-24d and 25a-25d allows the user to select a particular comfort level.

-10 -For example, comfort option 24a, 25a would be a 'cool' comfort level, comfort option 24b, 25b would be a 'less warm' comfort level, comfort option 24c, 25c would be a 'warm' comfort level, and comfort option 24d, 25d would be an 'extra warm' comfort level. The comfort options represent a different type of user interface. Conventional user interfaces are shown in Figures 5 and 6 and allow the user to select a particular setpoint temperature. Figure 5 shows a rotary dial 26 with a pointer 27 allowing the user to select a setpoint temperature by reference to a marked scale on the dial. Figure 6 shows a unit where the setpoint temperature is displayed on a screen 28 and where the user can adjust the setpoint temperature by pressing up and down buttons 29. These conventional types of user interface based on selection of a specific setpoint temperature are unsuitable for automation of adaptive comfort for three reasons. First, it encourages the user to think in terms of a preferred temperature at which they will be comfortable. Such a preference is not supported by the scientific evidence relating to user comfort and is contrary to the concept of the present invention. Second, if a specific setpoint temperature is selected, it will often have to be changed shortly afterwards in response to changes in the factors that affect comfort. This would lead to an undesirable perception by the user that the central heating system is challenging their judgement and not responding to their requirements. Third, it is a common misapprehension by users of continuously variable setpoint temperature controls that by setting the control to its maximum, the heating of the building is accelerated. This misunderstanding leads to significant inefficiency.

These problems are addressed by providing the user with a limited range of comfort options 24a-24d or 25a-25d. Each comfort option is marked qualitatively using a text label (e.g., 'cool', 'less warm', 'warm' and 'extra warm' -see Figure 5) or some form of graphical indication of the warmth it provides. For example, the range of comfort options may be displayed with a progressive shift in colour from cool tones such as grey or blue to warm tones such as orange or red. In practice it may be appropriate to combine text labels with graphical images or icons. The number of comfort options provided to the user will typically be the same as the number of daily profiles stored in the control unit 12.

Each comfort option 24a-24d and 25a-25d is associated with a different daily profile 20a-20d. For example, if the user selects comfort option 24a or 25a, which represents a 'cool' comfort level, the control unit 12 will use the first daily profile 24a which has the lowest overall average setpoint temperature. If the user selects comfort option 24d or 25d, which represents an 'extra warm' comfort level, the control unit 12 will use the fourth daily profile 24d which has the highest overall average setpoint temperature.

The published web page can also provide an interface allowing the user to set times when the building is unoccupied or when they expect to be asleep and do not require heating to the comfort level provided by the daily profile. At such times, a much lower, fixed, setpoint temperature can be used.

The control unit 12 stores the postcode for its location, which can be entered by the user or by an installation technician. It also stores an application program interface key (API key) provided by the Meteorological Office for their DataPoint system. These two data items allow the control unit 12 to obtain weather forecast information for its location from the DataPoint system using the Internet connection provided by the router 15. With the DataPoint system, the weather forecast information for the next day takes the form of eight values for each of four weather parameters. These parameters are temperature, wind speed, ultra violet index, and probability of precipitation. Each value is a forecast for a 3 hour period so the weather forecast information covers 24 hours in total. Ultraviolet index is a value from 0 to 7 expressing the risk of sunburn. However it can be interpreted as the level of sunshine. Probability of precipitation expresses the likelihood that there will be rain or snow in the given time interval, but it can also be interpreted as an estimate of humidity and complements the ultraviolet index in indicating when the sky is likely to be overcast and daylight levels low.

The software used by the control system 12 holds a set of weighting factors k/... k4 and threshold values v21 1),4 that are applied to the weather parameters provided by the DataPoint system to calculate an appropriate setpoint temperature adjustment. This adjustment will be described in more detail by an example of how the control unit 12 might operate over a 24 hour period.

-12 -Before midnight (e.g., at 23.45) the control unit 12 will obtain weather forecast information from the DataPoint system. For the purposes of this example, it will be assumed that the weather forecast information relates to just one weather parameter, namely the probability of precipitation (P1). But in practice, it will be readily understood that the weather forecast information will normally relate to other weather parameters such as temperature, wind speed, ultra violet index and also others not provided by the DataPoint system. The weather forecast information for the following 24 hours is shown in Table 1.

Time 00:00- 03:00- 06:00- 09:00- 12:00- 15:00- 18:00- 21:00- 02:59 05:59 08:59 11:59 14:59 17:59 20:59 23:59 P1 (?/b) 12 25 30 45 75 99.9 99.9 60

Table

It will be assumed that the user has selected a daily profile which is shown in Table 2. It will be readily appreciated that for the purposes of this example the daily profile has been simplified to include only eight setpoint temperatures (7) Time 00:00- 03:00- 06:00- 09:00- 12:00- 15:00- 18:00- 21:00- 02:59 05:59 08:59 11:59 14:59 17:59 20:59 23:59 T (°C) 18.5 18.5 18.5 18.9 19.3 19.6 20.0 20.0

Table 2

The control unit 12 uses the weather forecast information to calculate the adjustment to each setpoint temperature. The calculation of the adjustment for all other weather parameters are processed similarly, nitrous mittcmclis. The final adjustment is then the sum of all the individual adjustments arising from each weather parameter.

-13 -The threshold value v1,1 for probability of precipitation stored in the control unit 12 is 50%. No adjustment is made for any probabilities of precipitation that are lower than the threshold value.

The weighting factor k1 stored in the control unit 12 is 0.8. This is multiplied by the probabilities of precipitation that are higher than the threshold value to provide an adjustment that reflects the psychological and physical impact on comfort of increased humidity, loss of light, and actual rain. The adjustment values (Ai) are shown in Table 3.

Time 00:00- 03:00- 06:00- 09:00- 12:00- 15:00- 18:00- 21:00- 02:59 05:59 08:59 11:59 14:59 17:59 20:59 23:59 P1 (yb) 12 25 30 45 75 99.9 99.9 60 Al 0 0 0 0 0.6 0.80 0.80 0.48

Table 3

The adjustment values are added to the respective setpoint temperatures to provide modified setpoint temperatures (Tr) and a modified daily profile as shown in Table 4. This modified daily profile is then used by the control unit 12 to control the operation of the central heating system as described in more detail below.

Time 00:00- 03:00- 06:00- 09:00- 12:00- 15:00- 18:00- 21:00- 02:59 05:59 08:59 11:59 14:59 17:59 20:59 23:59 T (°C) 18.5 18.5 18.5 18.9 19.3 19.6 20.0 20.0 Al 0 0 0 0 0.6 0.80 0.80 0.48 I" (°C) 18.5 18.5 18.5 18.9 19.9 20.4 20.8 20.48

Table 4

For clarity of explanation it is assumed that the other weather parameters have values throughout the day that fall below their respective thresholds such that no adjustment -14 -from each is required. At 00.00 it is assumed that the user is asleep and has turned off the heating with a timer set to turn it back on again at 07:00. The room temperature in the building cools slowly from the level of about 20°C achieved the previous evening as determined by the daily profile. At 07:00 the control unit 12 measures the current room temperature using the room temperature sensor 13. The current room temperature is slightly below the setpoint temperature of 18.5°C applicable during the time period 06:00-08:59 so the control unit 12 operates the heat pump 10 to circulate hot water through the radiators 11. The control unit 12 will continue to regulate the heat output of the heat pump 10 so that the room temperature is close to the applicable setpoint temperature. In particular, during the period 07:00-08:59 the control unit 12 will keep the room temperature close to a setpoint temperature of 18.5°C. During the period 09:00-11:59 the control unit 12 will keep the room temperature close to a setpoint temperature of 18.9°C. During the period 12:00-14:59 the control unit 12 will keep the room temperature close to a setpoint temperature of 19.9°C. During the period 15:0017:59 the control unit 12 will keep the room temperature close to a setpoint temperature of 20.4°C. During the period 18:00-20:59 the control unit 12 will keep the room temperature close to a setpoint temperature of 20.8°C. The user has set a timer to stop heating at 23:00 so at that time the control unit 12 ceases to track the adjusted daily profile. During the period 21:00-22:59 the control unit 12 will keep the room temperature close to a setpoint temperature of 20.48°C At 23:45 the control unit 12 will obtain weather forecast information from the DataPoint system for the following 24 hours, thereby completing the cycle.

-15 -

Claims

CLAIMS1. A method of controlling a central heating system for heating a building, the method comprising the steps of providing a plurality of different time-varying setpoint temperature profiles, each of the time-varying setpoint temperature profiles having an early morning section with a first average setpoint temperature, an evening section with a second average setpoint temperature that is higher than the first average setpoint temperature, and a daytime section that transitions between the early morning and evening sections; a user selecting one of the time-varying setpoint temperature profiles as a baseline time-varying setpoint temperature profile; and using the baseline time-varying setpoint temperature profile to control the operation of the central heating system.
2. A method according to claim 1, wherein the different time-varying setpoint temperature profiles are predetermined.
3. A method according to claim 1 or claim 2, wherein the different time-varying setpoint temperature profiles are predetermined to provide different levels of comfort for the user.
4. A method according to any preceding claim, wherein between 3 and 6 different time-varying setpoint temperature profiles are provided.
5. A method according to any preceding claim, wherein each time-varying setpoint temperature profile includes a set of setpoint temperatures, each setpoint temperature being associated with a respective time period.
6. A method according to any preceding claim, wherein the first average setpoint temperature for the early morning section is substantially constant and/or the second average setpoint temperature for the evening section is substantially constant.

-16 -
7. A method according to any preceding claim, wherein the second average setpoint temperature is between about 0.5°C and about 2.0°C higher than the first average setpoint temperature.
8. A method according to any preceding claim, further comprising the steps of obtaining information indicative of the ambient climate external to the building; using the ambient climate information to modify the baseline time-varying setpoint temperature profile; and using the modified baseline time-varying setpoint temperature profile to control the operation of the central heating system.
9. A method according to claim 8, wherein the ambient climate information includes information about one or more weather-related parameters.
10. A method according to claim 9, wherein the ambient climate information includes a set of values for each weather-related parameter, each value being associated with a respective time period.
11. A method according to any of claims 8 to 10, wherein the ambient climate information is obtained from a commercial weather forecast service/data provider.
12. A control unit for controlling a central heating system using a method according to any preceding claim.
13. An apparatus comprising: a control unit For controlling a central heating system for heating a building, the control unit being adapted to store or access a plurality of different time-varying setpoint temperature profiles, each of the time-varying setpoint temperature profiles having an early morning section with a first average setpoint temperature, an evening section with a second average setpoint temperature that is higher than the first average setpoint temperature, and a daytime section that transitions between the early morning and evening sections; and -17 -a user interface through which the user can select one of the time-varying setpoint temperature profiles as a baseline time-varying setpoint temperature profile; wherein the control unit is further adapted to use the baseline time-varying setpoint temperature profile to control the operation of the central heating system.
14. Apparatus according to claim 13, further comprising a temperature sensor connected to the control unit.
15. Apparatus according to claim 13 or claim 14, wherein the control unit is further adapted to receive information indicative of the ambient climate external to the building.
16. Apparatus according to claim 15, wherein the control unit is further adapted to use the ambient climate information to modify the baseline time-varying setpoint temperature profile, and to use the modified baseline time-varying setpoint temperature profile to control the operation of the central heating system.
17 Apparatus according to any of claims 13 to 16, wherein the user interface provides different options to the user, each option being selected using a button or switch on the user interface.
18. Apparatus according to any of claims 13 to 17, wherein the user interface is a portable electronic device wirelessly connected to the control unit using a suitable wireless communication protocol.
19. Apparatus according to any of claims 13 to 18, wherein the control unit is connected to the Internet.
20. Apparatus substantially as described herein and with reference to Figures 1 to 4.-18 -Amendments to the claims have been made as follows: *** * *** * * * * ** * * * **** * *** **** * * * ** * * **CLAIMS1. A method of controlling a central heating system for heating a building, the method comprising the steps of: providing a plurality of different time-varying setpoint temperature heating profiles for a particular day, each of the time-varying setpoint temperature heating profiles having an early morning section with a first average setpoint temperature, an evening section with a second average setpoint temperature that is higher than the first average setpoint temperature, and a daytime section that transitions between the early morning and evening sections, wherein the different time-varying setpoint temperature heating profiles are predetermined to provide different levels of comfort for the user; a user selecting one of the time-varying setpoint temperature heating profiles as a baseline time-varying setpoint temperature heating profile for the particular day; and using the baseline time-varying setpoint temperature heating profile to control the heating operation of the central heating system.2. A method according to claim 1, wherein between 3 and 6 different time-varying setpoint temperature heating profiles are provided.3. A method according to claim 1 or claim 2, wherein each time-varying setpoint temperature heating profile includes a set of setpoint temperatures, each setpoint temperature being associated with a respective time period.4. A method according to any preceding claim, wherein the first average setpoint temperature for the early morning section is substantially constant and/or the second average setpoint temperature for the evening section is substantially constant.5. A method according to any preceding claim, wherein the second average setpoint temperature is between about 0.5°C and about 2.0°C higher than the first average setpoint temperature.6. A method according to any preceding claim, further comprising the steps of: obtaining information indicative of the ambient climate external to the building; using the ambient climate information to modify the baseline time-varying setpoint temperature heating profile; and using the modified baseline time-varying setpoint temperature heating profile to control the operation of the central heating system.7. A method according to claim 6, wherein the ambient climate information includes information about one or more weather-related parameters.8. A method according to claim 7, wherein the ambient climate information includes a set of values for each weather-related parameter, each value being associated with a respective time period.9. A method according to any of claims 6 to 8, wherein the ambient climate information is obtained from a commercial weather forecast service/data provider.10. A control unit for controlling a central heating system using a method according to any preceding claim.11. An apparatus comprising: a control unit for controlling a central heating system for heating a building, the control unit being adapted to store or access a plurality of different time-varying setpoint temperature heating profiles for a particular day, each of the time-varying setpoint temperature heating profiles having an early morning section with a first average setpoint temperature, an evening section with a second average setpoint temperature that is higher than the first average setpoint temperature, and a daytime section that transitions between the early morning and evening sections, wherein the different time-varying setpoint temperature heating profiles are predetermined to provide different levels of comfort for the user; and a user interface through which the user can select one of the time-varying setpoint temperature heating profiles as a baseline time-varying setpoint temperature heating profile for the particular day; * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * wherein the control unit is further adapted to use the baseline time-varying setpoint temperature heating profile to control the heating operation of the central heating system.12. Apparatus according to claim 11, further comprising a temperature sensor connected to the control unit.13. Apparatus according to claim 11 or claim 12, wherein the control unit is further adapted to receive information indicative of the ambient climate external to the building.14. Apparatus according to claim 13, wherein the control unit is further adapted to use the ambient climate information to modify the baseline time-varying setpoint temperature heating profile, and to use the modified baseline time-varying setpoint temperature heating profile to control the operation of the central heating system.15. Apparatus according to any of claims 11 to 14, wherein the user interface provides different options to the user, each option being selected using a button or switch on the user interface. * OM * * ** * * * * * 00 * . * 0000 * *** * * . 16. Apparatus according to any of claims 11 to 15, wherein the user interface is a portable electronic device wirelessly connected to the control unit using a suitable wireless communication protocol.17. Apparatus according to any of claims 11 to 16, wherein the control unit is connected to the Internet.18. Apparatus substantially as described herein and with reference to Figures 1 to 4.