WO2024018200A1

WO2024018200A1 - A heating control system for a building

Info

Publication number: WO2024018200A1
Application number: PCT/GB2023/051889
Authority: WO
Inventors: Peter James JENNINGS
Original assignee: Jennings Peter James
Priority date: 2022-07-21
Filing date: 2023-07-19
Publication date: 2024-01-25
Also published as: GB202210664D0; GB2620771B; GB2620771A

Abstract

In one aspect, a method is provided for updating a heating system control system for a closed fluid heating system in a building. The heating control system is initially configured as a weather- compensated system in which a valve is adjusted to control fluid flow in the closed fluid heating system based on a measured outside air temperature. The method comprises disengaging a control connection for adjusting the valve based on the measured outside air temperature; and reconfiguring the heating control system to use the valve in conjunction with an optimal water temperature control system. In another aspect, a heating control system is provided for a closed fluid heating system in a building. The heating system comprises: a primary circuit including a heat source for heating a fluid; and one or more secondary circuits configured to receive the heated fluid from the primary circuit, to circulate the heated fluid around the building, and to return the heated fluid to the primary circuit for re-heating. The control system is configured to: control the temperature to which the fluid is heated by the heat source in the primary circuit in accordance with a temperature set-point and occupant defined comfort, wherein the temperature set-point is determined using a prior measurement of energy demand from the building to be satisfied by the heating system; receive a temperature reading from a space in the building associated with a secondary circuit which includes a valve; determine from said temperature reading a localised change in circumstance with respect to the prior measurement of energy demand; and control the valve to compensate for the localised change in circumstance.

Description

A HEATING CONTROL SYSTEM FOR A BUILDING

Field

The present application relates to a heating control system for a building and to a method of updating and using such a heating control system to manage a heating system located in a building.

Background

Boilers are widely used in heating systems for heating water in buildings ranging from small domestic premises to much larger buildings, including office blocks, factories, recreational venues such as cinemas, leisure centres, etc, and so on. Such boilers are normally powered by burning gas (but sometimes oil or coal) to heat water in a primary circuit. The primary circuit is coupled to one or more secondary circuits which circulate hot water from the primary circuit around the building to provide heating (and often also hot water services, such as hand washing) for occupants of the building.

The control system for the heating system aims to maintain the building at a desired temperature. Thus if the building is below the desired temperature, there is a loss of comfort for the occupants of the building. Conversely, if the building rises above the desired temperature, this may also result in a loss of comfort. Furthermore, overheating the building implies an excess consumption of fuel by the boiler, which is increasingly problematic for both environmental and economic reasons.

In broad terms, a building receives heat from the boiler (in thermodynamic terms, a heat source) and loses heat to the external environment (in thermodynamic terms a heat sink). At a more detailed level, the building may receive additional heat, for example, from sunlight falling onto the building and/or from occupation and use of the building, such as the heat produced by the operation of lighting, computers, and so on. The sources and sinks of heat may be distributed differently across the building - for example, sunlight may illuminate the south side of a building but not the north side, whereas a prevailing cold wind might be from the east. Furthermore, such factors may be timedependent. The overall thermodynamic behaviour of a building is therefore complex and changeable. One particular problem, especially for moderate and large buildings, is that there is no single position in the building which has a temperature that is sufficiently representative to use as feedback for controlling the boiler.

A widely-implemented approach for controlling boiler output to manage the level of heating provided to a building can be considered (in some respects) as a supply-based strategy. In this approach, the desired level of heat supply may be determined from estimating the likely demand based on factors including measurements of outside temperature. Accordingly, this approach is sometimes described as weather-compensated. An example of this approach is described at: https://www.grantuk.com/knowledge-hub/education-area/weather-compensation/.

An alternative approach does not use weather compensation, but rather measures heating demand and uses this to control the heat supply. This approach, referred to herein as optimal water temperature (OWT) control, operates a central heating system with a view to producing the lowest water temperature which is capable of maintaining specified levels of occupant comfort. It will be appreciated that using the lowest temperature for the water (or other heat transfer medium) helps to minimise the energy usage of the central heating system. In a typical implementation of OWT, the control of the heat supply is achieved by adjusting a boiler set-point temperature (the temperature to which the boiler heats water in the primary circuit). In some respects, this latter approach can be regarded as using the whole building as a form of heating sensor.

Both of the above approaches represent an approximation to managing the (complex) overall thermodynamic behaviour of a building.

The EU Commission R&D project contract JOE3-6198-7010, produced a Final Report “Controller Efficiency Improvements for Commercial and Industrial Gas and Oil-Fired Boilers”, November 2001 , developed a model which can be used to calculate OWT as a heat source temperature control algorithm for centrally heated residential and non- residential buildings. WO 2003/074943 discloses one example of controlling heating using OWT in a building comprising a heating system, including a heat source for heating a medium, a circulation system for circulating the heated medium, and a control system for controlling the temperature to which the medium is heated in accordance with a temperature set point. An energy monitor generates a measure of energy consumed by the system, which is arranged for a predetermined period to have a fixed temperature set point. For a subsequent period, the temperature set point is set dependent on the energy used in the predetermined period and also current demand. Further information about OWT systems can be found, inter alia, in “A Simulation Study on the Energy Efficiency of Gas-Burned Boilers in Heating Systems. International Journal of Energy and Power Engineering” by Zaiyi Liao, Wei Xuan, Vol. 4, No. 6, 2015, pp. 327-332. doi: 10.11648/j . ijepe.20150406.11 , see also https://blog.swegon.com/uk/optimised-water-temperature-gives-lower-energy-consumption-and- higher-performance.

There is continued interest in the development of a heating control system for a building which provides a better approximation and reflection of the overall thermodynamic behaviour of a building, especially having regard to variable factors such as changes in solar heating.

Summary

The invention is defined in the appended claims.

In one aspect, a method is provided for updating a heating system control system for a closed fluid heating system in a building. The heating control system is initially configured as a weather- compensated system in which a valve is adjusted to control fluid flow in the closed fluid heating system based on a measured outside air temperature. The method comprises disengaging a control connection for adjusting the valve based on the measured outside air temperature; and reconfiguring the heating control system to use the valve in conjunction with an optimal water temperature control system.

In another aspect, a heating control system is provided for a closed fluid heating system in a building. The heating system comprises: a primary circuit including a heat source for heating a fluid; and one or more secondary circuits configured to receive the heated fluid from the primary circuit, to circulate the heated fluid around the building, and to return the heated fluid to the primary circuit for re-heating. The control system is configured to: control the temperature to which the fluid is heated by the heat source in the primary circuit in accordance with a temperature set-point and occupant defined comfort, wherein the temperature set-point is determined using a prior measurement of energy demand from the building to be satisfied by the heating system; receive a temperature reading from a space in the building associated with a secondary circuit which includes a valve; determine from said temperature reading a localised change in circumstance with respect to the prior measurement of energy demand; and control the valve to compensate for the localised change in circumstance.

A corresponding method for controlling a closed fluid heating system in a building is also provided.

Brief Description of the Figures

Various implementations of the claimed invention will now be described by way of example only with reference to the following drawings.

Figure 1 is a schematic diagram of an example of the primary circuit of a central heating system for a building.

Figure 2 is a schematic diagram of an example of the secondary and tertiary circuits of a central heating system which work in conjunction with the primary circuit of Figure 1 .

Figure 3 is a schematic diagram illustrating a weather effect on the secondary and tertiary circuits of the central heating system of Figure 2.

Figure 4 is a flowchart illustrating an example of a method for updating a heating control system as described herein.

Figure 5 is a flowchart illustrating an example of a method for controlling a heating system for a building as described herein.

Detailed Description

Central heating control using a building automation system (BAS)

Accurate control of occupant comfort temperatures with optimal use of energy for central heating systems are key objectives of a building management system. In the past couple of decades, especially for non-residential properties, programmable and computerised Building Automation Systems (BAS) have been widely installed for this purpose. Skilled BAS engineers apply established control strategies and bespoke programmes to manage heating system equipment and to develop solutions for comfort control and the efficient use of heating energy.

BAS is usually applied in buildings served by a central heating system in which hot water is the medium for the transfer of heat energy. The hot water is sourced from an appliance such as a boiler or heat pump in a primary circuit, and the generated hot water is then supplied to one or more secondary circuits. The hot water in these secondary circuits is generally pumped for distribution through a system of motorised valves to tertiary circuits in which heat energy is transferred from the hot water to air by various types of heat emitters such as radiators. These heat emitters are often locally temperature-controlled to satisfy local comfort demand.

The heating system in its entirety not only acts as a means for energy generation and distribution but also provides a framework for managing heating energy losses and wastage. The water temperature in the primary circuit depends directly on the amount of heat supplied by the boiler. As described above, a central heating system may control the operation of the boiler to meet comfort demand in the building with minimal waste heat and to replace physical heat losses from the building to the environment. However, the heat flow in most buildings is thermodynamically complex. Therefore most BAS implementations adopt an approximation which includes weather compensation by sensing outside air temperatures in order to adjust the temperatures of the primary and/or secondary circuits to compensate for variable weather and the resulting effect on heating demand. This use of weather compensation is effective in some weather conditions but less effective in others.

Overview of non-domestic central heating systems

A BAS seeks to ensure that adequate heat is delivered to the building for occupant comfort, i.e. to provide a temperature which is acceptable to the occupants, and also for hot water service (HWS) if relevant. The heat generated by the boiler in the primary circuit is distributed to the building via the secondary and tertiary circuits which serve heat emitters such as radiators, air handling units, etc. It is usual for the secondary circuits and the associated tertiary circuits to be assigned to different zones in the building. These different zones may be used for different purposes and different comfort levels serving one or more rooms or spaces. Zone space comfort is generally monitored by temperature sensors as a comfort demand reference against which zone heat is supplied.

One known type of secondary heating circuit is a Constant Temperature (CT) heating circuit, which may potentially be weather-compensated by a weather compensation strategy as described above (although in practice, CT heating circuits are normally not weather compensated). The secondary CT circuits (and/or the tertiary circuits connected thereto) may host heat emitters such as Air Handling Units (AHU’s) or Fan Coil Units (FCU’s). In these devices, air is warmed by passing over heater batteries or coils. Another type of CT secondary circuit may be used for hot water services (HWS), which usually have a lower requirement for hot water than heating does. On the other hand, the hot water for HWS is often provided at a higher temperature than the hot water used for heating.

Variable temperature (VT) secondary circuits are also known. These VT circuits are normally weather-compensated to deliver water at various temperatures (usually lower than CT water temperatures) to serve tertiary heat emitters such as radiators or panel heaters. Local controls may be used to maintain desired space temperatures, usually by controlling the flow of the variable temperature water into the radiators (or other emitters). The radiators emit heat into internal building space to replace losses to the outside ambient environment (or to other, cooler, internal portions of the building). The rate at which heat is lost depends, inter alia, on the thermal resistance of the building (which is generally constant) and the outside temperature (which is dynamic or changeable according to the weather). As described herein, equipment designed and installed in a VT (and/or potentially CT) secondary circuit to support a weather-compensation strategy may be redeployed for use in an optimal water temperature heating control strategy.

Building controls for weather compensation

Weather compensation can be provided for primary temperatures or for secondary circuit temperatures to condition their supply temperature to tertiary circuits to reflect a change in heating demand due to weather variation. This approach for temperature adjustment involves the application of prevailing outside air temperature (OAT) as a data input. OAT sensing is important for a number of building heating control attributes such as Optimum Start/Stop and Frost protection. Although some building scientists have argued that the direct application of OAT sensed data is not the best way to determine current weather-related primary or secondary temperatures to control the supply of heat to tertiary circuits and emitters for comfort demand in a building, nevertheless, it is regarded by many as internationally established “best practice” for both domestic and non-domestic buildings.

In practice, measured values for sensed OAT are provided as input to a formula or graph (known as a compensation curve) to directly adjust primary (boiler or heat pump) set-point temperature and/or secondary VT circuit heat supply to related zones and tertiary circuits to meet comfort demand. Such weather compensation is generally applied in different ways according to whether the building is domestic or non-domestic. In the former case (and also for some smaller nondomestic properties), the compensation calculation is generally applied as an adjustment to the primary temperature or boiler set-point, usually for the boiler flow but sometimes for the return, thereby providing direct optimal control of the heat source (e.g. a boiler or heat pump).

In the latter case of non-domestic buildings, especially medium to large non-residential buildings which include multiple heating circuits, the compensation calculation is managed by a modern building control system (usually BAS) which applies weather compensation techniques to the secondary VT circuits. In such cases, primary temperatures for delivering heat to CT or HWS secondary circuits are rarely compensated. Rather, such primary temperatures are normally set by the BAS to ensure adequate (weather-compensated) heat for the VT secondary circuits and also the CT circuits.

A BAS weather compensation system for a VT secondary circuit generally includes a VT motorised mixing (or diverting) valve. This valve is usually a 3-port device with primary hot water flowing in through a first port to a chamber where it is mixed with (or partially diverted to) cooler water which is being returned from a secondary circuit for re-heating and which flows in through a second port. The weather compensating temperature, derived from the compensating slope, is implemented usually as a scaled voltage signal supplied to the actuator of the valve which modulates (adjusts) the flow of water out through the third valve port to control the VT compensated water temperature supplied to the appropriate zone and tertiary emitters to meet comfort demand.

The VT circuit supply temperature may be determined using OAT in conjunction with a compensating slope (curve) which directly maps outside air temperature to the compensated VT supply temperature setting. As applied to the valve, this mapping has no direct reference to the zone or collective space comfort demand. However, the gradient or slope of the weather compensation curve can be changed or developed by user adjustment of its co-ordinates to empirically develop a weather compensation supply temperature to satisfy such zone or collective space comfort temperatures. These temperatures can be read by sensors as a desirable zone comfort demand reference to fine tune the empirical curve co-ordinate adjustment. The VT compensated valve actuators can then be used as a supply temperature limiting device by the BAS to shut off zone or collective space compensated heat supply if sensed zone temperatures exceed the BAS upper temperature limit for space comfort.

However, some aspects of VT weather-compensation may lead to inaccuracy or inefficiency within the system according to one or more of the following factors:

1 . The determination of a weather compensating curve for a given building is usually performed by an experienced engineer based on judgement and experience; but the determination may be subject to some degree of error.

2. The determination of the compensating slope generally errs on the high side with respect to weather-compensated temperatures, i.e. the result is that in the event of inaccuracy, the building will generally be heated to a temperature which is too high rather than too low.

3. The primary supply temperature set-points for water flowing into the first port of the VT mixing valve are derived with no reference to changing comfort demand.

4. Primary supply heat (typically hot water from the primary circuit) entering the VT mixing valve via the first port may be wastefully degraded through mixing with cooler return water received via the second port to arrive at the VT weather-compensated supply flow temperature.

5. The operation of the VT mixing valve typically involves at least some primary heat energy (from the primary circuit) being unused or degraded and then returned to the primary source for reheating.

(In more detail, this approach is considered to be wasteful because the heat energy from the boiler already undergoes losses through its casing as well as distribution pipework before it gets to the valve, at which point more supply energy is lost by mixing it with colder return water. Therefore any water leaving the boiler which is at a higher temperature than the calculated compensated VT set-point is sent back by the valve via the return water to the boiler).

In addition to the above issues, OAT based weather-compensation is at best an approximation of the optimal thermodynamic heat supply to meet demand from a central heating system and the building it serves.

Replacing weather compensation techniques in buildings with optimal water temperature (OWT) control.

As described herein, the thermodynamic intelligence of modern building controls may be raised by replacing a traditional weather compensation strategy with an optimal water temperature strategy. With the introduction of optimal water temperature, the traditional weather compensation technique and its associated expensive equipment and processes are no longer needed. In other words, equipment which has been used for weather compensation becomes redundant for this purpose. However, such equipment may be redeployed as described herein to improve space temperature demand control to provide optimal water temperature with an additional heating demand compensation component with which to improve further the optimisation of system supply temperature set-points.

Such an approach offers significant benefits for the reduction of heating energy and CO2 emissions in most non-residential buildings, particularly those with modern building controls. With few exceptions, such buildings are currently using modern but thermodynamically questionable weathercompensation techniques. As described herein, the integration with OWT helps to address the thermodynamic shortcomings of these existing heating control systems, whilst at the same time making selective alternative use of equipment and processes installed in such modern BAS installations to improve further the benefits of OWT.

OWT exploits the thermodynamic limitations of the internationally accepted ‘best practice’ for heating systems in both domestic and non-domestic central heating systems, in particular in relation to weather compensation. Weather compensation has been used globally for decades as a way to improve efficiency and comfort in such buildings and (in the absence of a practical alternative offered by the international building controls supply industry) is recognised by building scientists worldwide as an adequate solution for such heating control. It provides a convenient but approximate weather corrective adjustment to system temperatures to help optimise the temperature set-points at which water (or other medium for energy transfer, distribution and space heat emission) should be heated by appliances such as boilers and heat pumps to accommodate both demand (desired heating comfort and optionally HWS) and weather-related losses while ensuring a low level of waste. However, detailed computer modelling has shown that true weather compensation along with heating demand compensation is a complex thermodynamic challenge for control systems.

The OWT approach as used herein was developed by extensive modelling of a wide range of centrally heated buildings and their heating systems, applying their physical constants together with a simulation of various weather conditions. With a few simple programmable inputs, an OWT system performs an iterative process to emulate the thermodynamic profile of a given building and heating system which is adaptive to weather variation on a daily basis. From this process, optimal primary water temperature set-points may be set for the rest of the day (as described in WO 2003/074943, as referenced above).

As described herein, OWT may be integrated with computerised primary circuit control systems (primarily BAS) for non-domestic buildings to help reduce heating energy costs and carbon emission and to improve occupant comfort. In particular, for non-domestic buildings with central heating systems managed by BAS, existing weather compensation techniques may be replaced with OWT algorithms for controlling the primary heat source using optimal water temperatures. Although OWT remains an approximation of a complex thermodynamic challenge, scientific research has supported its use in building heating control systems to provide a more efficient approximation than OAT based weather compensation

A traditional OAT based weather compensation system can be viewed as a supply side technique with very little recognition of building heating demand (other than as used empirically for reference in setting the co-ordinates of the weather compensating curve). In contrast, OWT technology does take into account heating demand to develop its optimal primary water supply temperatures. A replacement from weather compensation to OWT control as described herein includes a change of use of secondary VT circuit system controls which had previously (e.g. at installation) been configured to implement weather compensation. This re-use in an OWT context of what would otherwise be redundant VT compensating valves and circuitry provides an additional dimension to OWT to refine its existing capabilities. In effect, redundant secondary heating supply side compensation equipment is converted (repurposed) into an additional balancing function between optimal total system heating supply and demand.

Existing OWT technology typically develops a daily optimal water temperature to determine the efficient supply of heat to the system - typically using an early morning reference for determining the thermal mass of the building as the basis for setting OWT (such as described above in WO 2003/074943). During the day, OWT updates a temperature set-point for the boiler to heat water based on measured heat demand. The demand can be measured according to the heat energy provided by the boiler to heat the return water in the primary circuit up to the temperature set-point (based on the known operating properties of the boiler). Alternatively (or additionally) demand may be determined based on the difference between (i) the measured temperature of the primary water supply flow (from the boiler), (ii) the measured temperature of the primary water return (from the secondary circuit(s), and (iii) the water flow rate into the boiler.

The existing OWT approach generally considers the heat loss (or gain) by a building in aggregate. However, a building (particularly with significant glazing) may be affected by solar gain on the east side during the morning and the west side in the afternoon, and the south side for both. This localised variation in solar gain is not directly accounted for in the aggregate approach of existing OWT. A similar situation may arise (for example) if a strong cold wind initially impacts a north facing side of a building, but subsequently the wind direction shifts to impact an east facing side of the building. Both such conditions can present the heating system with a change in localised demand (e.g. for an individual zone) which has not been accounted for in determining the OWT aggregated zonal demand at the start of the day. This may present one or more zonal heat emitters with a change in heating load which may be challenging to accommodate within the use of existing OWT primary water set-points.

In other words, there may be unpredicted, relatively short-term heat gain or loss in different parts of the building, i.e. localised to certain parts of the building rather than being shared across the entire building. Such a short-term heat gain or heat loss may have little impact if it is small in scale compared with the thermal mass (capacity) of the building. However, if the heat gain or heat loss is significant compared with thermal mass of the building (this applies in particular to solar gain for buildings with substantial glazing), this can affect space temperatures and comfort in a relatively quick timeframe, thereby presenting the heating system with a balancing problem. In such cases, the thermodynamic profiling for OWT development, which is built on an aggregate heat loss and prediction for the building as a whole, may be confused by (for example) an unexpected high inflow of solar heat energy from outside the building into a localised portion of the building (such as the southfacing side of the building). As described herein, an OWT implementation is able to address the above issue by exploiting sensed internal temperature information to enhance the ability of OWT to accommodate such shortterm, localised changes. Note that such internal sensors are generally provided in a building as a part of (or linked with) the BAS. Hence the approach described herein may be based on the re-use of existing (already installed) hardware, rather than imposing any requirement for new hardware.

By way of example, sensed temperatures for actual spaces within a building may be used to detect short-term extraneous changes. In particular, based on the sensed temperatures, a suitable control signal may be sent to the actuator of a VT compensation valve to control the primary flow of OWT heating water in response to the unplanned but sensed changes in space temperature (and hence demand). In some cases, a building may be equipped with a secondary VT circuit for each of the different zones of the building. OWT optimisation can then be employed as the main basis for providing a balanced supply of heat to the different zones, with the converted space sensing valves then being used for fine adjustment of the OWT flow according to specific thermal conditions.

In practice, handling short term space or zone temperature gains arising from solar heating are the most likely beneficiary of such an approach. With an effective reduction in source heat demand (due to the supplementary solar heating), unused heat from the OWT supply may be returned through the return port back to the heat source for re-heating to the OWT set-point. The OWT system may have a return temperature sensor and when this effective reduction in system demand due to solar gain becomes apparent, the optimal OWT supply can be automatically reduced to save energy and improve comfort. In addition, by converting all VT weather-compensated supply valves to space temperature demand control valves, the optimised primary water can be distributed to ensure that space temperatures are efficiently supplied with stable comfort.

Figure 1 is a schematic diagram of an example of the primary circuit 100 of a central heating system for a building. Figure 2 is a schematic diagram of an example of the secondary and tertiary circuits 200, 300 of a central heating system for a building. It will be appreciated that the primary circuit 100 of Figure 1 may be utilised in combination with the secondary and tertiary circuits 200, 300 of Figure 2, such that the combination provides a substantially complete central heating system for a building.

Referring first to Figure 1 , this shows a primary circuit having two boilers 110A, 110B (referred to collectively as 110) for heating water as part of the central heating system. It will be appreciated that although the primary circuit 100 of Figure 1 comprises two boilers, in other implementations, there may be only a single boiler or more than two boilers. In addition, it will be appreciated that boilers 110 represent an energy source for providing the central heating, and may typically be powered by burning gas or oil. However, the primary circuit 100 may utilise any appropriate energy or heating source (or combination of sources), including, for example, a heat pump, a geothermal heat source, a solar heat source, and so on. In addition, the primary circuit 100 and also the secondary and tertiary circuits 200, 300 generally use water as the medium to supply and distribute heat from the boilers 110 to the building and the description of Figures 1 and 2 will proceed on this basis. However, it will be appreciated that the central heating system shown in Figures 1 and 2 is not limited to the use of water, and any other suitable medium may be adopted for the supply and distribution of heat within the building.

Each of the two boilers 110A, 110B is provided with a respective pump 120. The boilers 110A, 110B (and their respective pumps 120) are configured in parallel. In general, the primary circuit 100 forms a relatively simple loop in which water flows clockwise around the loop (with respect to the depiction in Figure 1 ). In particular, water is pumped by pumps 120 through the boilers 110 to produce the primary supply flow 102 of water for heating. The primary supply flow 102 travels to circuit interface 150, where water in the primary circuit 100 may pass into the secondary circuit 200 (as described below with reference to Figure 2). Water is then received back from the secondary circuit 200 by the primary circuit 100, also via circuit interface 150, to form the primary return flow 103. Depending on the heating requirements, in particular at times of low demand, some of the primary supply flow 102 may not pass through the circuit interface 150 to the secondary circuit(s) 200, but may remain in (and circulate around) the primary circuit.

The water in the primary return flow 103, which will have cooled as it traverses the secondary circuit 200, is fed back by the pumps 120 through their respective boilers 110A, 110B, for (re) heating to function as the primary supply again, whereby the above cycle is performed repetitively. The primary circuit arrangement of Figures 1 and 2 is generally known as a Low Loss Header which protects the boilers from the pressure fluctuations of secondary circuit pumping arrangements. Another common system has the water flow and return water collected in separate flow and return manifolds for direct connection to pumped secondary circuit flow and return circuits.

Figure 1 further depicts a control system 130, a temperature sensor (thermometer) 140 coupled to the primary supply flow 102, and a temperature sensor 141 coupled to the primary return flow 103. The control system 130 may include a BAS which may be configured to control the heating system in the building using, for example, a weather compensation strategy as described above. The BAS is normally provided with a communications network (not shown in Figure 1 ) which may be implemented, for example, as a local area network to provide wired and/or wireless links between the various electronic and electrical components of the heating system, typically including the pumps, boilers, thermometers and valves, to support the exchange of data and commands between these components.

In some implementations, the temperature sensor 140 may directly measure the water temperature by being at least partly located within the water flow. In other implementations, the temperature sensor 140 may indirectly measure the water temperature, for example via an additional component (not shown in Figure 1 ) which is in good thermal contact with both the water and the temperature sensor 140. The temperature sensor 141 may likewise measure the water temperature of the primary return flow 103 directly or indirectly. The difference between the temperature (Tout) of the supply flow 102 as measured by thermometer 140 and the temperature (Trtn) of the return flow 103 as measured by thermometer 141 provides an indication of the temperature drop (and hence heat loss) of the water passing around the secondary circuit(s) 200.

The amount of heat energy (i.e. demand) provided by the primary circuit 100 scales with (i) the temperature of the water, and (ii) the flow-rate of the water. The above temperature difference combined with a measurement of the flow rate (not shown in Figure 1 ) may therefore be used in some implementations to estimate the demand for applying optimal water temperature control.

In a typical implementation, the boiler pumps 120 are integrated with each boiler and are small and designed to continuously pump water through their respective boilers 110 for re-heating (or not, according to the setting of the boiler 110). The pumps 120 then deliver heated water from the boilers, at any set-point temperature, to the primary supply flow 102. The primary water is then directed according to the laws of fluidics. If there is secondary circuit demand, the primary supply flow 102 is drawn out of the primary circuit 100 by the larger secondary circuit pumps (as discussed below with reference to Figure 2). If there is no secondary circuit demand, the primary supply flow will remain in the primary circuit 100 and the boiler pumps 120 will re-cycle the primary water back around the primary circuit to the boiler(s) for re-heating. In this latter case, heat loss is limited to the primary circuit 100 and therefore relatively low, likewise heat demand from the boilers 110 is also low. In contrast, in the former case, the heat loss experienced within the secondary circuits is relatively high, and likewise the heat demand from the boilers 110 is also higher.

Another (or additional) method for estimating demand for applying OWT is based on measuring the boiler output used to heat the return water back to the OWT temperature set-point. The control system 130 may then manage the temperature of the water in the primary circuit in accordance with the measured demand. By way of example, the control system may estimate heat output from the boiler based on metering the flow of fuel (e.g. gas or oil) to the boiler as it is operated as part of the heating system.

In some implementations, the demand on the heating system may be measured based on a scaled voltage which is used to actuate a fuel valve controlling the supply of fuel to the boiler(s). Thus if the temperature of the primary water supply 102 (e.g. as measured by Tout 140) starts to fall below a temperature set point, the control system 130 may raise the voltage so that the fuel valve(s) open further. This allows more fuel to enter the boiler(s) 110, thereby maintaining the temperature set-point of the primary water supply 102. Conversely, if the temperature of the primary water supply 102 starts to rise above a temperature set-point, the voltage set by the control system 130 may be lowered to cause the fuel valve(s) to close somewhat. This allows less fuel to enter the boiler, and thereby decreases the temperature of the primary water supply. The voltage applied to the boiler(s) to maintain a temperature set point therefore provides a measure of demand in the system, which may in turn by used to modify the temperature set point in accordance with OWT control. Note that if the heat source is a heat pump (rather than a boiler), a similar approach may be adopted based on controlling the electrical supply to the compressor of the heat pump and monitoring energy demand from an electricity meter.

Accordingly, in the OWT approach, if the measured demand is increasing, the temperature set point for the primary water supply 102 is increased, while if the measured demand is decreasing, the temperature set point for the primary water supply 102 is reduced. The boiler output can then be set (thermostatically controlled) to satisfy the new temperature set-point.

Referring now to Figure 2, this is a schematic diagram of an example of the secondary and tertiary circuits 200, 300 of a central heating system for a building. As noted above, the secondary and tertiary circuits 200, 300 of Figure 2 may be used in combination with the primary circuit 100 of Figure 1 , such that the combination provides a substantially complete central heating system for a building. The central heating system of Figures 1 and 2 is typically utilised to provide weather- compensated control of heating for the building. However, as described herein, such a central heating system may also be utilised to control heating of the building based on enhanced OWT (such as depicted in the method of Figure 5). A transition from weather-compensated control to enhanced OWT control may be achieved by modifying the operation of the control system 130, but without involving any other hardware changes.

The example shown in Figure 2 has three secondary circuits 200A, 200B, 200C (referred to collectively as secondary circuits 200), but other implementations may have only single secondary circuit, two secondary circuits, or more than three secondary circuits, according to the circumstances of any given implementation. Typically, each secondary circuit corresponds to a different physical zone of the building - thus in Figure 2, secondary circuit 200A is associated with Zone 1 , secondary circuit 200B is associated with Zone 2, and secondary circuit 200C is associated with Zone 3. The provision of multiple secondary circuits 200A, 200B, 200C corresponding to respective zones allows different heating in different zones (according to the settings applied to the associated secondary circuits).

In the example shown in Figure 2, each secondary circuit 200 has (feeds) a corresponding tertiary circuit 300, whereby a tertiary circuit may be implemented, for example, by a radiator or other form of heating device (heat emitter). It will be appreciated that each tertiary circuit is generally located in the same zone as the corresponding secondary circuit. Although Figure 2 shows one tertiary circuit 300 associated with each secondary circuit 200, there may be multiple (or zero) tertiary circuits associated with a given secondary circuit, and the number of associated tertiary circuits may vary from one secondary circuit to another. Moreover, the multiple secondary circuits 200 may all share the same configuration, or may have different configurations. For example, in Figure 2, the secondary circuits 200A and 200B are configured as VT circuits, which are typically provided with at least one radiator and/or panel heater, whereas the secondary circuit 200C is configured as a CT circuit, which is typically provided with at least one air handling or fan coil unit.

In operation, heated water comprising the primary supply flow 102 is received from the primary circuit 100 via the circuit interface 150 (see also Figure 1 ). This water then circulates around the secondary and tertiary circuits 200, 300, before being directed back to the primary circuit 100 as primary return flow 103, again via the circuit interface 150.

Each secondary circuit 200 includes a respective pump 220 to support the circulation of heating water around that secondary zone (and any associated tertiary zones). A further pump 240 is also shown in Figure 2; this is shared between the secondary circuits 200 and is used to facilitate return of water from the secondary circuits 200 back to the primary circuit 100 as described above. The skilled person will be aware of other possible configurations of pumps 220 within the secondary and tertiary circuits 200, 300. The pumps 220, 240 are generally responsible for drawing sufficient primary supply hot water from the circuit interface 150 of Figure 1 to perform the desired level of heating for each zone and then to return this water back to the primary circuit for reheating by the boiler.

Also shown in Figure 2 are three temperature sensors (or thermostats), indicated as T1 , T2, and T3. Each temperature sensor is associated with a respective tertiary circuit (and its associated secondary circuit). Note that there may be zero, one or more temperature sensors for any given zone, and the number of temperature sensors may differ from one zone to another. Furthermore, the temperate sensors may be primarily associated with a secondary circuit 200 or with a tertiary circuit 300. These temperature sensors T1 , T2, T3 provide temperature information for the physical space associated with their respective zones. This temperature information can be fed back (by a wired or wireless connection) to the control system 130 to help the control system manage the heating system in the building, for example by way of space temperature compensation. The heating system may also contain one or more temperature sensors which are located outside the building to measure outside air temperature (OAT) (these external temperature sensors are not shown in Figure 2). Again, the temperature information acquired by these external temperature sensors can be fed back by a wired or wireless connection to the control system 130 to help the control system manage the heating system in the building, for example, by way of weather compensation. (However, as described in more detail below, the configuration of Figure 2 may be used to implement a heating control system which does not utilise weather compensation).

In non-domestic systems, especially those controlled by BAS, a communications network is generally used to transmit information between the control system and other components of the central heating system, such as the boilers, pumps, and mixing valves (as described below). Such a communications network may be provided, for example, as a local area network, such as an Ethernet. This communications network may support both wired and wireless communications between the various components of the central heating system.

As shown in Figure 2, the two secondary circuits 200A, 200B which are VT circuits also include a respective mixing valve 230A, 230B (referred to collectively as valves 230). As previously described, these valves 230 may be installed as VT weather-compensated supply valves and are three-port devices, with (i) a first port acting as a first input to receive primary supply flow 102 via the circuit interface 150; (ii) a second port acting as a second input to receive a controllable portion of the water that has already circulated around the majority of the secondary circuit 200 and would otherwise be returned to the primary circuit 100 via the circuit interface 150 as the primary return flow 103, and (Hi) a third port acting as a first output to allow the mixed water from the first and second ports to circulate around the secondary circuit which contains the mixing valve 230.

In general terms, the mixing valve can be adjusted to control the relative amount of water fed into the third port from the primary supply flow and the secondary circuit return flow. The secondary circuit return flow is cooler than the primary supply flow (because heat has been transferred out from the water as the water circulates around the relevant secondary circuit). Accordingly, to provide a secondary circuit (and associated tertiary circuit) with a relatively high level of heating, the amount of cooler water entering the second port from the secondary circuit return flow should be decreased (or potentially zero) relative to the primary intake through the first port in order to utilise more heat provided by the primary supply flow 102. The secondary circuit is then supplied via pump 220 with water that is therefore taken all or largely from the primary supply flow, and so is relatively hot. In contrast, to provide a secondary circuit (and associated tertiary circuit) with a relatively low level of heating, the amount of cooler water entering the second port from the secondary circuit return flow is increased relative to the primary intake through the first port.

Each of the valves 230A, 220B may therefore be equipped with an actuator (not shown in Figure 2) that is used to control the amount of water input from the second port relative to the amount of water input from the first port. These actuators may be controlled by the control system 130 using, inter alia, information provided by temperature sensors located outside the building. In such an implementation, the output from the 3^rd port may therefore be referred to as a weather-compensated VT flow.

Figure 3 is a schematic diagram illustrating the effect of weather on the secondary and tertiary circuits of the central heating system of Figure 2. As was the case with Figure 2, the secondary and tertiary circuits 200, 300 of Figure 3 may be used in combination with the primary circuit 100 of Figure 1 , such that the combination provides a substantially complete central heating system for a building. Since the components of the heating system shown in Figure 3 are the same as those in Figure 2, the description of these components will not be repeated. However, Figure 3 specifically illustrates a localised weather effect on the building, and hence on the heating system for the building. In particular, the sun associated with Zone 1 in Figure 3 indicates that this zone is currently receiving significant solar heating.

As described herein, the control system 130 in Figure 1 may be constructed or configured in different ways to perform the control of the secondary and tertiary circuits of Figures 2 and 3. In particular, the components of Figures 2 and 3 may be controlled to operate a weather-compensated control scheme as described above, or these components may be configured to use a modified (enhanced) version of the OWT approach. It will be appreciated that a permanent transition from the former approach to the latter approach is supported by the ability of both approaches to run on the same equipment, including the same communication network, which is typically provided by, or in combination with, a BAS. In other words, this transition does not involve the expense and complexity of installing new hardware (or modifying former hardware), but rather the transition Is implemented by a reconfiguration of the existing hardware.

Figure 4 is a flowchart illustrating an example of a method for converting a heating control system for a building from a weather-compensated system to a OWT system as disclosed herein. At the commencement of the method, the building operates a weather compensation system in which measured outside temperatures are used to control the setting of at least one valve (operation 410).

This system is now updated firstly by disconnecting the valve from the weather compensation system (operation 420) and then installing an OWT control system which is connected to the valve (operation 430). Note that in this approach, the valve remains plumbed into the heating system in the same manner, however, the control system which is used to manage the operation of the valve is changed, from a weather compensation system to an OWT system. The disconnection of the valve in operation 420 and the connection of the valve in operation 430 may in some implementations involve re-wiring, but in many cases may be implemented as a software change. For example, software running on a BAS may be reconfigured, such as by deactivating software used by the weather compensation system to connect to and control the operation of the valve, and installing and/or activating new software in order to implement the OWT control system, including connecting to the valve to allow the OWT control system to manage the operation of the valve.

In effect, the operations shown in Figure 4 allow the valve to be repurposed for use as part of the OWT control system, and hence the investment in providing the valve as part of the heating system is maintained. It will be appreciated that although Figure 4 illustrates just a single valve being re-purposed, in some cases the heating system may comprise multiple valves which are repurposed in this manner (e.g. different valves from different secondary circuits).

Figure 5 is a flowchart illustrating an example of a method based on OWT for controlling a heating system for a building as described herein (and such as shown by the combination of Figures 1 and 2/3). This method may be implemented by suitable programming of the control system 130. This method may be used, for example, by a heating control system which has been updated using the method shown in Figure 4.

The method of Figure 5 commences with performing a process to measure the energy demand from the heating system (operation 510) and then performing OWT control based on this measured demand (operation 520). It will be appreciated that these two operations match (and may be implemented by) the approach disclosed in WO 2003/074943.

During the performance of OWT control in operation 520, the control system also receives information on internal temperatures within the building being heated (operation 530). This information generally comprises readings from temperature sensors (e.g. thermometers) fixed in different locations within the building. These readings therefore reflect the temperature at the different locations in the building, which may be associated with different zones, different secondary circuits and different tertiary circuits. For example, temperature readings may be obtained from different rooms, offices, etc.

At operation 540, the control system 130 reviews the received temperature readings, generally on an ongoing basis as the readings are received by the control system 130. The control system checks to see if there is a discrepancy at a given location between an expected temperature (determined using an existing OWT approach) and a measured temperature - for example, if the measured temperature is significantly above or below an expected temperature to provide the required user comfort.

A typical reason for such a discrepancy is a localised variation in solar heating which is not identified as part of the measured energy demand from operations 510, 520. For example, one portion of a building may be in bright sunlight, and hence receive significant solar heating, whereas another portion of a building may be in shade, and hence receive little or no solar heating. This is illustrated schematically in Figure 3, in which only zone 1 is associated with an image of the sun. Another example of such a localised discrepancy between measured and predicted temperature might arise from wind variations. For example, a cooling wind might be received from the north, but the wind direction may then shift around to be received from the east. It will be appreciated these examples of solar and/or wind factors are by way of example for causing a temperature discrepancy, and such a discrepancy may arise from various meteorological (and non-meteorological) features.

Since OWT is usually developed over a short period in the morning based on aggregated demand from all emitters as engines for space comfort in all zones, it does not differentiate between the localised demand at the zone level, but this localised zone-level demand may vary from one zone to another based, for example, on solar heating effects as discussed above. Re-purposing of the mixing valves as described herein enables the aggregated OWT heat to be apportioned dynamically to satisfy comfort in each zone. In other words, rather than managing OWT heat supply on the basis of an average level of (say) solar gain across the entire building, the OWT heat supply can now be controlled at the zone level using the valves 230 to accommodate localised effects such as solar gain.

Accordingly, at operation 550, the heating control system 130 reacts to the detected localised discrepancy between measured and expected temperatures. This discrepancy is normally manifested by a difference between a user defined comfort set-point temperature and a measured temperature for a given location. The heating circuits are then controlled to reflect the detected demand and remove or reduce the discrepancy. For example, if the measured temperature is too high compared to the user-specified temperature, this indicates that heating demand for the given location has fallen, and hence the supply of heating to this location can be lowered. Conversely, if the measured temperature is too low compared to the programmed user comfort set-point temperature, this indicates that heating demand from the given location has risen, and hence the supply of heating to this location can be increased.

There are various ways in which the control system 130 can manage the heating system to supply more or less heating to the given location to bring the measured temperature back into line with the programmed user set-point temperature for that location. For example, one way of varying the supply of energy is based on mixer valves 230 such as illustrated in Figures 2 and 3. These mixer valves output heating water for the secondary (or tertiary) circuit associated with the given location having the discrepant measured temperature. The two inputs to each mixer valve are heated water from the primary supply flow, and water which has already traversed around the secondary circuit (and so is cooler than the primary supply flow). The control system 130 can use a powered actuator to control the ratio of water provided by these two inputs, namely the hotter primary supply and the cooler secondary return, and this in turn controls the temperature of the water output from the mixer.

Note that such mixer valves are already frequently deployed to provide weather compensation for a BAS. The above approach allows these mixer valves to be repurposed for use in conjunction with an OWT implementation, thereby preserving the value of investment into the provision of such mixer valves and their associated controls. In other words, a previous VT weather compensated heat supply valve for a zone is repurposed to become a comfort demand compensating valve for the zone. Zone space temperature sensors (T1 , T2, T3) now provide a reference for space comfort demand control using the actuators of the mixing valves.

In operation, water from the primary supply flow enters through the first port of valve 230. The temperature of this primary supply flow generally matches the primary OWT set-point based on the daily thermodynamic profile of the building (as obtained earlier in the day). The water entering the valve through the second port for mixing with the primary supply water is supplied from the cooler secondary circuit which is water returning to the primary circuit for re-heating to the OWT set-point. The actuated flow of water exiting the third port of the valve 230A chamber is formed from a controlled combination of water from the first and second input ports based on the programmed comfort set point for the zone and the space temperature sensor (T1 ).

The repurposed configuration shown in Figure 3 supports system balancing by adjustment of the heat supply to individual zones, where each individual zone may have different and varying heating demand loads through the day. Although OWT provides the calculated control of the primary supply to meet aggregated zone demand (i.e. across all zones), the converted valves provide a facility to distribute heating flow effectively in a localised manner at secondary circuit level to serve individual (and changing) zone demand. As an example, a south facing zone which is exposed to solar gain will demand less heat from the heating system and the control system 130 may control the valve actuator to set the mixer valve accordingly in response to the comfort sensor for this zone to compensate for the localised heating. Another zone (e.g. north facing) may be exposed to a cold wind, and this localised cooling may require an increased share of aggregated heat. In this case, the space temperature signal provided (directly, or indirectly via the control system 130) to the converted zone valve actuator operates to open the valve to introduce more heat into the space to compensate for the localised heat loss.

It will be appreciated that the control of heating supplied to a given location to address a discrepancy between measured and user-defined space temperature can be implemented in a number of ways (without necessarily using the mixer valves described above). For example, in some implementations, pumps 220 (see Figures 2 and 3) may have a facility to control flow rate, hence the flow rate for a given zone may be increased by the control system to provide more heating or reduced to provide less heating to compensate for any observed discrepancy between measured and requested temperature.

In addition, an OWT strategy may support an effective change of use of an OAT sensor and the redundant weather compensation curve, particularly in buildings with a high content of glass. By way of approximation, OWT can be regarded as using an entire building and its thermal mass as a weather sensor - rather than using a single OAT sensor for this purpose (which bypasses the dynamic effect of building mass). Accordingly, an OAT sensor may be used to detect a sudden increase in solar activity which, in particular, affects glazed surfaces leading to often substantial space temperature increases. A conventional weather compensation curve may then be redeployed to modify the earlier predicted optimal water temperature setpoint (or, if appropriate, to disable the heating system completely for one or more zones).

The above approach provides a well-controlled central heating system based on optimal water temperature control of the primary circuit so as to satisfy demand for comfort heat and to replace physical heat losses from the building with a low (ideally minimal) level of waste heat. Accordingly, this approach replaces a traditional weather compensation strategy with a more efficient OWT solution. Furthermore, the approach described herein supports a change in the use of VT weather compensation system equipment, in particular the pipework of the secondary circuit, plus associated valves and controls.

The outcome of this conversion from weather compensation to an OWT approach (with the enhanced reuse of existing equipment) provides a control framework which improves the efficiency of OWT. The ability of OWT to learn and factor the aggregated demand from all zones within the building facilitates control of the optimal water temperature in the primary circuit. Furthermore, for heating systems which previously applied VT weather compensation techniques but are now replaced by OWT, their VT valves are available for fine tuning a zone in response to localised changes in heating demand as detected from single or averaged comfort space temperatures. Moreover, such fine tuning is generally available without the need for any hardware modification. Accordingly, the OWT approach may be integrated with the hardware previously used for weather-compensation to provide an enhanced solution for a heating control system.

The approach described herein therefore encourages the integration of OWT with BAS to replace more outdated weather and load compensation strategies and is more attractive to building operators than simply adopting OWT and ditching weather-compensated BAS because elements of BAS, such as the fine control of VT circuits, may be retained (and repurposed). Accordingly, this can be perceived as a network enhancement to the existing BAS investment, rather than discarding this prior investment. In addition, the use of OWT set-point algorithms within the BAS network also enables a system integrator to remotely access and analyse all BAS attributes and network data. This data relates to the entire heating system and the heat flow dynamic between the OWT enabled primary circuit and the secondary and tertiary circuits serving locally controlled comfort space temperatures. With the integration of an OWT controlled primary circuit into the BAS framework, it is no longer necessary for VT secondary circuits to host BAS weather compensation strategies.

The approach described herein therefore helps to improve the thermodynamic substance of modern building controls, replacing their traditional weather compensation strategies and by doing so, especially in the case of larger non-domestic buildings, allowing expensive equipment to be redeployed to facilitate primary heating optimisation with significant benefits for the reduction of energy and CO2 emissions.

The approach may be implemented using a heating control system for controlling a heating system in a building. Such a heating system includes a heat source, such as a boiler, for heating a fluid medium, such as water, which is then circulated within the building via a primary circuit and secondary and tertiary circuits as known in the art. The control system manages the temperature to which the water (or other medium) is heated by the boiler (or other heat source) in accordance with a temperature set point. In other words, the boiler heats the primary supply water to maintain a temperature equal (or close to) the temperature set-point. This temperature set-point represents the optimal set-point which is approximated and modified for sustainability for the duration of daily heating to reflect the dynamically changing thermodynamic state of the building.

As described herein, a heating control system for a building may be updated firstly by disconnecting a valve from the weather compensation system and then installing an OWT control system which is connected to the valve. In effect, this allows the valve to be repurposed for use as part of the OWT control system, and hence the investment in providing the valve as part of the heating system is maintained. The heating control system updated in this manner may control the flow of water from the primary circuit into a secondary circuit dependent on the heating demand of the building or one or more zones within the building. The OWT control system may incorporate a compensation system having one or more temperature sensors inside the building, and the monitored temperatures may exhibit localised variations due to factors not present when the OWT was configured during the predetermined time interval as described above. The OWT control system may then use the re-purposed valve to control the flow of water to compensate for these localised variations. Accordingly, repurposing the valve(s) as described herein not only protects the investment in such valves after conversion from a heating control system based on weather compensation to one based on OWT, but also goes beyond a conventional OWT approach, by controlling and adjusting the heating in different zones in response to localised factors, such as solar heating. Accordingly, the approach described here supports a more flexible and efficient approach for comfort heating within the building. In conclusion, while various implementations and examples have been described herein, they are provided by way of illustration, and many potential modifications will be apparent to the skilled person having regard to the specifics of any given implementation. Accordingly, the scope of the present case should be determined from the appended claims and their equivalents.

Claims

1 . A method for updating a heating system control system for a closed fluid heating system in a building, wherein the heating control system is initially configured as a weather-compensated system in which a valve is adjusted to control fluid flow in the closed fluid heating system based on a measured outside air temperature, said method comprising: disengaging a control connection for adjusting the valve based on the measured outside air temperature; and reconfiguring the heating control system to use the valve in conjunction with an optimal water temperature control system.

2. The method of claim 1 , wherein the heating system comprises: a primary circuit including a heat source for heating a fluid; and one or more secondary circuits configured to receive the heated fluid from the primary circuit, to circulate the heated fluid around the building, and to return the heated fluid to the primary circuit for re-heating.

3. The method of claim 2, wherein the heating control system uses the optimal water temperature control system to control the temperature to which the fluid is heated by the heat source in the primary circuit in accordance with a temperature set-point determined by the optimal water temperature control system.

4. The method of claim 3, wherein the temperature set-point is determined using a prior measurement of heat energy demand from the building to be satisfied by the heating system for providing occupant defined comfort.

5. The method of claim 4, further comprising: receiving a temperature reading from a space in the building associated with a secondary circuit which includes the valve; determining from said temperature reading a localised change in circumstance with respect to the prior measurement of energy demand; and controlling the valve to compensate for the localised change in circumstance.

6. The method of claim 5, wherein there are multiple secondary circuits, each secondary circuit being associated with a different respective zone of the building, and wherein the space in the building from which the temperature reading is received is located in the zone associated with said secondary circuit which includes the valve.

7. The method of claim 6, wherein the change in circumstance represents a significant increase or decrease in solar heating received by part of the building and/or a significant increase or decrease in wind cooling of part of the building.

8. The method of any of claims 5 to 7, wherein the valve is a motorised valve for operation by the heating control system and the method further comprises controlling the valve to compensate for the localised change in circumstance in accordance with the optimal water temperature system.

9. The method of any of claims 3 to 8, further comprising measuring the current heat energy demand by metering the amount of fuel used to heat, to the temperature set-point, the fluid returned by the one or more secondary circuits to the primary circuit.

10. The method of any of claims 2 to 9, wherein the valve is a three-port mixing valve and the heating control system comprises an actuator for use by the heating control system to control output from the valve.

11 . The method of claim 10, wherein the mixing valve comprises: (i) a first port acting as a first input to receive fluid from a primary supply flow;(ii) a second port acting as a second input to receive fluid that has circulated around a secondary circuit; and (iii) a third port acting as a first output to allow mixed fluid from the first and second ports to circulate around the secondary circuit.

12. The method of claim 11 , wherein the valve is used by the heating control system to adjust the relative contribution to the fluid exiting from the third port of (i) the fluid from the first port and (ii) the fluid from the second port, to control the heating effect of the fluid exiting from the third port.

13. The method of any of claims 2 to 12, wherein the one or more secondary circuits comprise a variable temperature circuit which includes at least one tertiary circuit including a radiator and/or heating panel.

14 The method of any preceding claim, wherein the heat source comprises a boiler or a heat pump, and/or wherein the fluid comprises water.

15. The method of any preceding claim, wherein the heating control system includes or links to a building automation system.

16. A heating control system for managing a heating system for a building, the heating control system having been updated using the method of any preceding claim.

17. A heating system for a building comprising: a primary circuit including a heat source for heating a fluid; one or more secondary circuits configured to receive the heated fluid from the primary circuit, to circulate the heated fluid around the building, and to return the heated fluid to the primary circuit for re-heating; a valve; and a heating control system according to claim 16.

18. A method for operating a heating control system for a closed fluid heating system in a building, wherein the heating system comprises a primary circuit including a heat source for heating a fluid, and one or more secondary circuits configured to receive the heated fluid from the primary circuit, to circulate the heated fluid around the building, and to return the heated fluid to the primary circuit for re-heating; wherein the method comprises the heating control system: controlling the temperature to which the fluid is heated by the heat source in the primary circuit in accordance with a temperature set-point and occupant defined comfort, wherein the temperature set-point is determined based on a measurement of current heat energy demand from the building to be satisfied by the heating system and/or wherein the temperature set-point is determined using a prior measurement of energy demand from the building to be satisfied by the heating system; receiving a temperature reading from a space in the building associated with a secondary circuit which includes a valve; determining from said temperature reading a localised change in circumstance with respect to the prior measurement of energy demand; and controlling the valve to compensate for the localised change in circumstance, including updating the heating control system according to the method of any of claims 1 to 15.

19. A heating control system for a closed fluid heating system in a building, wherein the heating system comprises: a primary circuit including a heat source for heating a fluid; and one or more secondary circuits configured to receive the heated fluid from the primary circuit, to circulate the heated fluid around the building, and to return the heated fluid to the primary circuit for re-heating; wherein the heating control system is configured to: control the temperature to which the fluid is heated by the heat source in the primary circuit in accordance with a temperature set-point, wherein the temperature set-point is determined based on a measurement of current heat energy demand from the building to be satisfied by the heating system; receive a temperature reading from a space in the building associated with a secondary circuit which includes a valve; determine from said temperature reading a localised change in circumstance with respect to the prior measurement of energy demand; and control the valve to compensate for the localised change in circumstance, the heating control system according to claim 20, the heating control system having been updated according to the method of any of claims 1 to 15.