GB2490125A

GB2490125A - Hydronic radiant heating and cooling system comprising a phase change material

Info

Publication number: GB2490125A
Application number: GB1106535.6A
Authority: GB
Inventors: Michael Holland Goddard
Original assignee: CAPLIN SOLAR SYSTEMS Ltd
Current assignee: CAPLIN SOLAR SYSTEMS LTD
Priority date: 2011-04-18
Filing date: 2011-04-18
Publication date: 2012-10-24
Anticipated expiration: 2031-04-18
Also published as: GB2490125B; GB201106535D0

Abstract

The system comprises a closed-loop fluid circuit, one or more packs 8 containing a phase change material, and an energy management controller. At least part of the circuit 6 is located in or adjacent a structural element 10,12 of a building space. The one or more packs are located in or adjacent the structural element. A working fluid is circulated around the circuit under the command of the controller and is in a heat exchange relationship with the one or more packs. The system may include a device 30, such as a photovoltaic thermal hybrid panel, heat pump or thermal energy store, to heat or cool the working fluid, wherein the device is fluidly connected to the circuit by a manifold 2. The system may include a ground energy store 40 to store heat energy during the summer months for release during winter. The store may be further connected with a heat pump 50. The system may include temperature sensors, valves and pumps controlled by the controller. The working fluid may be water or a water glycol mix. A method of heating or cooling a building space is also claimed.

Description

TITLE

Heating and cooling systems

DESCRIPTION

Technical Field

The present invention relates to heating and cooling systems for buildings, and in particular to heating and cooling systems that can be installed in walls, floors and ceilings to provide space heating and cooling.

Background Art

In December 2006 the UK Government launched the Code for Sustainable Homes (CSH) which required progressive reductions in the environmental impact of new houses. In particular, a timetable of progressively greater targets for the reduction of energy use has been adopted, with an aim of having a zero carbon' output by 2016 for private housing and 2013 for public housing. A zero carbon' house is one that has zero net emissions of carbon dioxide from all energy use within the home'. This means in effect that it must generate more energy over a year than it uses.

The UK Government is currently considering incoorating parts of the Code into the building regulations with an emphasis on progressive increase in energy efficiency and the reduction of carbon dioxide emissions.

The inventor believes that a number of technical problems need to be solved before zero carbon houses can become a practical and economic reality. These include: 1. Most demand for heat and electrical energy occurs when the sun is not shining, either at night on a diurnal basis, or in winter on a seasonal basis. There is no readily available means of storing either electricity or heat for when it is most needed.

2. Photovoltaic (PV) cells or panels -the tatter being a packaged, interconnected, assembly of PV cells -are a common method for energy generation and generate electricity from sunlight but they give maximum output when they are cool and their performance degrades as they become heated by the sun.

3. Another common method for capturing heat from the sunlight is the use of solar thermal panels. However, the south facing roof space required to accommodate both PV cells for electricity generation and solar thermal panels for the generation of adequate heat for a zero carbon' home is not easily found on conventionally designed roofs.

There are two existing, but as yet little used technologies, which, if applied in combination under control of a single energy management controller, could address each of these shortcomings and make it practical to store and release heat energy while maximising the generation of electrical energy. They are: (i) the use of photovoltaic thermal (PV/T) hybrid cells in which heat energy is removed from the conventional PV cells by fluid cooling to enable them to operate at more efficient temperatures while also capturing heat energy in a similar manner to conventional solar thermal panels, and (ii) phase change materials (PCMs) in which latent heat absorbed during the solid-liquid phase change is used as a storage medium for heat energy. When a PCM reaches its melting temperature it is capable of absorbing and storing significant amounts of heat while maintaining an almost constant temperature until the material is transformed to the liquid phase. The stored latent heat is then subsequently released if the PCM is transformed back to the solid phase. Common types of PCM include eutectics, typically having a phase change temperature below 0°C, and salt hydrates (inorganic) or organic materials, typically having a phase change temperature above 0°C.

Under floor heating systems are well known and include a single-or multi-layer tubing or pipework loop that connects to a manifold. The tubing is typically laid in a serpentine pattern and clipped to an underlying layer of insulation. A concrete screed is then laid on top of the insulation and the tubing. The tubing can also be installed in timber suspended floors, or in walls or ceilings.

The manifold is typically connected to a boiler (or other heat source such as a heat pump) and has an in-built circulation pump, blending valve, pressure gauge etc. to control the flow of heated fluid from the boiler to each zoned area of tubing at the correct temperature.

Summary of the Invention

The present invention provides a hydronic radiant heating or cooling system which may be installed in a building, and in particular a building that aims to meet the zero carbon' standard. The system comprises a closed-loop heating or cooling circuit, at least part being located in or adjacent a structural element (e.g. floor, wall or ceiling) of a building space, fluid being circulated around the circuit under the control of an energy management controller to heat or cool the building space, and one or more packs or cassettes containing phase change material (PCM) located in or adjacent the structural element in heat exchange with the fluid and adapted to heat or cool the building space, e.g. by radiant heating or cooling.

Heat energy is actively transferred between the fluid and the PCM in a controlled manner. For example, the PCM can be heated or cooled in an active' manner by circulating heated or cooled fluid around the closed-loop circuit under the control of the energy management system. Such operation might be contrasted with PCM located in building structures which operates passively' by responding only to changes in ambient conditions.

For space heating then the system is typically operated so that the PCM absorbs and stores heat energy when such heat energy is readily available (e.g. during the daytime) and subsequently releases the stored heat energy to provide radiant space heating when other sources of heat energy are not readily available (e.g. during the night-time). The heat energy is provided by the fluid that is normally heated by an external heating device before it is circulated past the packs or cassettes containing the PCM.

When the PCM cools and solidifies, the stored heat energy is radiated into the building space through the structural element, which may optionally be constructed to optimise the transfer of the stored heat energy from the packs or cassettes containing the PCM into the building space. The aim is to keep the building space at a substantially constant temperature, but in practice daytime temperatures will normally be slightly higher than those during the night. While the PCM is absorbing heat energy -or is being charged' -then the heat energy from the fluid will be mostly transferred into the PCM, although some heat energy will be radiated through the structural element into the building space. There will be times when the stored heat energy in the PCM will not be sufficient to provide the necessary space heating.

However, this is likely to be at times when an altemate heat source will be in the use and the temperature at the structural element of the building space (e.g. the under floor temperature) may be increased above the phase change temperature of the PCM.

The system can also be operated in reverse to provide space cooling. In this case, the system is typically operated so that the PCM absorbs and stores heat energy from the building space (e.g. during the daytime) to provide space cooling and the stored heat energy is subsequently removed from the PCM by the fluid that is normally cooled by an external cooling device.

As mentioned above, the closed-loop heating or cooling circuit preferably includes a heating or cooling device for heating or cooling the fluid (e.g. water or a water/glycol mix). Any suitable device may be used, but the inventor believes that the following devices have certain technical and environmental benefits, most particularly when they are used together: a photovoltaic thermal (PV/T) hybrid array, a thermal energy store and a heat pump, for example an air source heat pump (ASHP) or a ground source heat pump.

The inventor believes that the use of PCM in heat exchange with the heated or cooled fluid circulated around the closed-loop heating or cooling circuit by the energy management controller addresses the requirements for heating and cooling over the diurnal cycle (e.g. storing heat energy generated during the daytime to provide space heating during the night-time) while the thermal energy store is preferably designed for the long-term storage of heat energy, over a period of weeks or months, for example, and addresses the seasonal cycle (e.g. storing heat energy generated during the summer to provide space heating during the winter). The thermal energy store may have any suitable construction but can be provided in the form of a ground or earth energy store with heat collecting coils selectively connected to another heating or cooling device for part of the year (e.g. to the PV/T array during the summer so that fluid heated by the PV/T array can be circulated through the heat collecting coils to warm the surrounding earth) and to the closed-loop heating or cooling circuit for the rest of the year (e.g. during the winter where fluid circulated through the heat collecting coils can be heated by the surrounding earth and then used to provide heat energy to the PCM). The heat pump can be used to provide hot water for the building but can also be used in conjunction with the thermal energy store as a secondary source of heat energy for the PCM.

The heating or cooling circuit preferably further includes a pump for circulating the fluid around the circuit. The pump can be operated under the control of the energy management controller.

The heating or cooling circuit preferably further includes valves (e.g. solenoid valves) for controlling the movement of the fluid around the circuit. The valves can be operated under the control of the energy management controller.

The heating or cooling circuit can further include a heating or cooling manifold. The manifold can be similar to those used in conventional under floor heating systems and can include at least one inlet and at least one outlet connected to an outlet and inlet, respectively, of an extemal heating or cooling device by suitable tubing or pipework.

A plurality of inlets and outlets may be provided, each inlet and outlet connected to a different heating or cooling device. Each circuit defined by an inlet and outlet of the manifold may have its own pump and valves so that it is independent of the others.

The energy management controller will typically control the system so that the fluid that is circulated in heat exchange with the PCM is heated or cooled only by a single heating or cooling device at any time. This may involve selecting one of a plurality of different closed-loop heating or cooling circuits together with the appropriate pumps etc. The energy management may control the system in response to temperature information provided by temperature sensors as discussed in more detail below.

The manifold can include at least one inlet (or supply) and outlet (or return) connected to a loop of suitable tubing or pipework -typically of the sort used in conventional under floor heating systems -which is at least partly located in or adjacent the structural element. If the manifold is to supply heating or cooling fluid to a plurality of zoned areas, each having its own loop, then a plurality of inlets and outlets can be provided. A particular zoned area may also have more than one loop.

The manifold can include a blending valve for controlling the temperature of the fluid circulated through the tubing loop(s). The manifold can include a pump for circulating the fluid around the closed-loop heating or cooling circuit, including the tubing loop(s). The pump can be operated under the control of the energy management controller. The manifold may include additional components for the normal operation of the heating or cooling system such as actuators, valves, pressure gauges etc. The system can include temperature sensors providing temperature information to the energy management controller. The temperature sensors may be positioned to provide temperature information of the fluid at various locations around the closed-loop heating or cooling circuit, e.g. at the packs or cassettes containing the PCM, at the outlet of each external heating or cooling device, at the manifold etc. Temperature sensors may also be positioned to provide the ambient temperature outside the building and the internal temperature within the building space to be heated or cooled.

The heating or cooling circuit, and in particular the tubing loop, is preferably interspersed between neighbouring packs or cassettes. The packs or cassettes containing the PCM can be incorporated into an under floor concrete screed. A steel reinforcing mesh can be placed on top of the packs or cassettes before the screed is poured.

The packs or cassettes can contain any suitable PCM having the desired phase change temperature.

The energy management controller is preferably electronic and controls the operation of the closed-loop heating or cooling circuit and its various components. The energy management controller for the system may be a stand-alone unit or be incorporated within an overall building management system.

The present invention further provides a method of heating or cooling a building space by circulating fluid around a closed-loop heating or cooling circuit, at least part of the circuit being located in or adjacent a structural element of the building space, under the control of an energy management controller, the method comprising the steps of: heating or cooling the fluid before it is circulated through the at least part of the circuit that is located in or adjacent the structural element; transferring heat between the fluid and phase change material located in or adjacent the structural element; and using the phase change material to heat or cool the building space, e.g. by radiant heating or cooling.

Drawings Fig. 1 is a schematic drawing showing a hydronic radiant heating system according to the present invention; and Figs. 2 to 6 are schematic drawings showing different flow modes of the heating system of Fig. 1.

Although the following description concentrates on a hydronic radiant heating system, it will be readily appreciated that the same principles can be easily applied to a cooling system where the fluid that is circulated around the under floor heating system is cooled rather than heated.

With reference to Fig. 1 a hydronic radiant heating system according to the present invention consists of an under floor heating system 1 as a means of delivering a controlled supply of heat energy from different heating devices. The heating system is installed in a building, e.g. a domestic house.

The under floor heating system includes a heating manifold 2 having an outlet 4a (or supply) and an inlet 4b (or return) connected to a tubing loop 6 to provide radiant under floor heating to a building space. Although only one tubing loop is shown in Fig. 1 it will be readily appreciated that two or more tubing loops may be connected to the same heating manifold, each tubing loop providing radiant heating to the same building space or, more typically, to different building spaces.

Packs 8 containing phase change material (PCM) with a phase change temperature Te for the solid-liquid phase of about 25°C are embedded in a concrete floor screed 10 and are positioned to be above and in heat exchange contact with the tubing loop 6 of the under floor heating system. In one practical arrangement the tubing loop 6 extends between and around neighbouring packs 8. A 75 mm deep, gypsum based, fast-flow concrete screed will encase the packs 8 and the pipework that forms the tubing loop 6. A steel reinforcing mesh 12 is placed over the packs 8 to strengthen the screed and ensure the stability of the packs during the pour. The packs 8 are filled with salt hydrates whose melting point may be selected over a wide temperature range. When filled and sealed, the packs 8 are adequately load-bearing for use in domestic situations. The packs 8 are 500 mm long, 250 mm wide and 45 mm deep and provide about 50 kWh latent heat per cu metre; i.e. > 2 kWh per square metre of floor space. The packs 8 can be positioned on I-beams in-filled with foam insulation (not shown).

The heating manifold 2 is connected to external heating devices by separate loops of suitable tubing or pipework. A first closed-loop heating circuit can be defined by the tubing loop 6 of the under floor heating system, the manifold 2 and the tubing loop 14 connecting the manifold to an array 30 of photovoltaie thermal (PV/T) cells. A second closed-loop heating circuit can be defined by the tubing loop 6 of the under floor heating system, the manifold 2 and the tubing loop 16 connecting the manifold to a ground energy store 40. A third closed-loop heating circuit can be defined by the tubing loop 6 of the under floor heating system, the manifold 2 and the tubing loop 18 connecting the manifold to a heat pump 50. Valves (e.g. solenoid valves) integrated within the heating manifold 2 can control the circulation of fluid around one or more of the closed-loop circuits at any time. Heated fluid is provided to the heating manifold 2 from the heating devices and is then circulated through the tubing loop 6 of the under floor heating system 1. Heated fluid can also be circulated from the heating manifold 2 to other devices, e.g. from the PV/T array 30 to the ground energy store 40 or from the ground energy store to the heat pump 50. An additional bypass tubing loop 20 for the circulation of fluid from the ground energy store 40 to the heat pump 50 is shown in Fig. 1 for ease of clarity but it will be readily appreciated that such circulation can also take place through the heating manifold 2. The circulation of the fluid around the various closed-loop circuits is controlled by the operation of pumps (not shown) that are also integrated within the heating manifold 2.

The number of photovoltaic thermal (PV/T) hybrid cells is arranged to suit the energy requirement of the building. In one practical arrangement the roof of the building will be covered with 40 square metres of Volther Powertherm PV/T cells manufactured under license from Solimpex Solar Energy Corp. Such PV/T cells are capable of extracting more energy per square meter of roof area than either conventional photovoltaic (PV) cells or solar thermal cells alone. Since space heating normally requires more energy than providing domestic hot water (DHW), and since south facing roof area is a finite resource, the ability to capture the maximum power is a key factor in the design of the heating system. Typically the peak electrical output is 190 W per square metre while the peak heat output is close to 500 W per square metre.

The Volther Powertherm PV/T cell prioritises thermal energy over electrical energy generation by covering the cells with a glass sheet inhibiting heat loss from the front surface in order that it can be removed by the cooling fluid circulating around the back face.

The heat pump 50 is an exhaust air heat pump (EAHP) similar in design to the NIBE 410P pump supplied in the UK by NIBE Energy Systems Limited and provides mechanical ventilation and heat recovery (MVHR) to the building, generating heat -10 -from the waste energy extracted from the building whose primary role is to provide DHW, but which can contribute to space heating during the winter. The heat pump typically consumes a total of 1 kW at full rated power. This is made up of 650 W compressor motor, a 100 Vt circulation pump with the remainder driving the MVHR fans. The MVHR fans collect waste heat from the kitchen, bathrooms and other areas of the building with south facing glazing and use it as their energy source for the heat pump. The heat pump 50 also has an immersion heater provided as a back-up and for occasionally heating the hot water to 60°C as a safety measure against bacteria.

The ground energy store 40 (or earth energy bank') is constructed below the building foundations as a heat sink. The ground energy store 40 uses conventional heat collecting coils (not shown) found in commercial ground source heat pumps to deliver and extract heat energy. In one practical arrangement the ground energy store 40 consists of an area of 50 square metres of earth lying below the basement floor of the building bounded by the concrete foundations. It is formed by digging out the area between the foundations after they are cast down to a depth of 650 mm. The area is then covered with 50 mm sand and heat collecting coils of the slinky' type are laid over the whole area. A further 50 mm layer of sand is then laid so that the coils are in a sand sandwich' to give good thermal contact. Heave boards are then attached to the inner face of the foundation walls to form a heat retaining barrier. The void is then filled in and a layer of polythene laid on top to within 300 mm of the edge of the area. Assuming that the effective heat sink will extend 400 mm below the coils then, in a clay based sub-soil, a 50 square metre area will provide the equivalent heat capacity of about 100 tons of water. At peak output in high summer, the PV/T array 30 will be generating some 20 kW of heat energy. In theory, one sunny day will raise the teniperature of the ground energy store by 1°C. By the end of an average summer, the ground energy store 40 will have a temperature high enough to directly heat the building by melting the PCM contained within the packs 8. As the winter progresses and its temperature reduces, it will provide an excellent source of high grade heat as input to the heat pump 50, which will then be able to operate with a very high coefficient of performance to supplement the heat energy of the ground store. In a prolonged cold winter, the ground energy store could become exhausted in which case the immersion heater of the heat pump 50 can be used on an economy tariff to melt the PCM during the night so that it can provide its latent heat for space heating during the following day.

An electronic energy management controller (not shown) which receives temperature information from a variety of temperature sensors 24 and outputs control signals to control the operation of the heating system (e.g. to control the in-built pumps and valves of the heating manifold 2) to optimise heat distribution from the heating devices. The energy management controller can receive temperature information from temperature sensors (not shown) located outside the building and within the building space to be heated. Suitable proprietary energy management controllers can be used.

The heating system typically operates as follows: Daytime Solar energy falls on the PV/T array 30 providing electrical energy to power all electrical devices in the building including the compressor and circulating pumps of the EAHP 50 (<0.75 kW). Heat energy (normally about 2.5 times the electrical energy from the PV/T array) in the form of heated fluid -typically a water/glycol mix -is circulated around the first closed-loop heating circuit by a pump under the control of the energy management controller (Fig. 2). After being heated by the PV/T array 30, the fluid is circulated through the tubing loop 6 of the under floor heating system 1 where the heat energy can be absorbed by the PCM contained within the packs 8.

The PCM is heated until it reaches its phase change temperature Tc and starts to gradually melt.

Once the PCM is fully melted then any surplus heat energy from the PV/T array 30 is diverted to the ground energy store 40 by the energy management controller (Fig. 3).

More particularly, after being heated by the PV/T array 30, the fluid is circulated through the heat collecting coils of the ground energy store 40 to heat the surrounding earth. -12-

If the heat energy from the PV/T array 30 is not sufficient, and the measured temperature Ti of the PCM falls below its phase change temperature Tc, then the energy management controller will circulate fluid from the ground energy store 40 to the under floor heating system 1 through the second closed-loop heating circuit (Fig. 4). If the measured temperature T2 of the heated fluid from the ground energy store falls below the phase change temperature Tc of the PCM then the energy management controller will circulate fluid from the heat pump 50 to the under floor heating system through the third closed-loop heating circuit (Fig. 5).

Night-time When the measured temperature T3 of the heated fluid from the PV/T array 30 falls below the measured temperature Ti of the PCM contained within the packs 8 then the circulation of heated fluid through the first closed-loop heating circuit is stopped by the energy management controller. Latent heat is radiated from the PCM into the building space as it cools and gradually starts to solidify.

Seasonal effects During the summer far more heat energy is generated than is used. Once the PCM contained within the packs 8 has been melted by the heated fluid provided by the PV/T array 30 circulating through the first closed-loop heating circuit (Fig. 2), the surplus heat energy is transferred to the ground energy store 40 (Fig. 3), which has a very large thermal capacity. By the end of the summer it will have reached a temperature far in excess of the surrounding earth.

During the autumn there will begin to be a requirement for space heating in the evenings and at night. This requirement for space heating will mostly be met from the PCM contained within the packs 8 with the heat energy being replaced during the day by the heated fluid from by the PV/T array 30.

During the winter there will be a deficiency of heat energy from the PV/T array 30 and there will be a need to rely on the heat energy stored in the ground energy store -13 -over the summer. For a time the temperature of the ground energy store 40 will be high enough for it to provide heated fluid directly to the under floor heating system, i.e. fluid can be circulated around the second closed-loop heating circuit (Fig. 4) where it will be heated by the surrounding earth as it flows through the heat collecting coils. Eventually the temperature of the ground energy store 40 will have cooled to the point where the heat energy is diverted as an input to the heat pump 50 through the bypass tubing loop 20. This in turn will be called on to provide only a modest rise in temperature enabling it to operate at very high coefficient of performance (COP).

Heated fluid from the heat pump can be circulated around the third closed-loop heating circuit (Fig. 5).

In extreme conditions of late-season enduring cold weather then it may be necessary for the immersion heater of the heat pump 50 to be used to provide additional heat energy. Under these circumstances it will typically run only during an economy tariff Is to provide heated fluid to the under floor heating system, i.e. heated fluid from the immersion heater can be circulated around the third closed-loop heating circuit during the night to melt the PCM contained within the packs 8, which will then provide radiant space heating during the day (Fig. 6).

In spring, as the days lengthen and get warmer, the heating system will gradually recharge itself starting with the PCM and only when this is fully melted will the ground energy store 40 receive the surplus heat energy provided by the PV/T array 30.

Energy Management System The energy management system will typically use the following logic to control fluid flows (F) between the PV/T array 30, the ground energy store 40, the heat pump 50 and the tubing loop 6 of the under floor heating system 1: Tc = phase change temperature of the PCM Ti = measured temperature of the PCM T2 = measured temperature of the fluid leaving the ground energy store -14-T3 = measured temperature of the fluid leaving the PV/T array F = FO then all fluid circulation OFF F = Fl then fluid circulation from the PV/T array to the under floor heating system through the first closed-loop heating circuit ON (Fig. 2) F = F2 then fluid circulation from the PV/T array to the ground energy store ON (Fig. 3) F = F3 then fluid circulation from the ground energy store to the under floor heating system through the second closed-loop heating circuit ON (Fig. 4) F = F4 then fluid circulation from the ground energy store to the heat pump and fluid circulation from heat pump to the under floor heating system through the third closed-loop heating circuit ON (Fig. 5) F F5 then fluid circulation from the heat pump (immersion heater ON) to the under floor heating system through the third closed-loop heating circuit ON IF Ti <Tc AND T3 > Ti THEN F = Fl IF Ti > Tc AND T3 <Ti THEN F = FO IFTi>TcANDT3>Ti THENF=F2 IFTi <TcANDT3<T1ANDT2>Tl THENF=F3 IFTi<TcANDT3<T1ANDT2<T1THENF=F4 IFFF4ANDT1 <TcTHENFF5 In practice a temperature margin of one or two degrees above and below Ti and T2 will be allowed to ensure complete solidification or melting of the PCM contained within the packs 8 before a change of flow occurs.

Claims

-15 -CLAIMS1. A hydronic radiant heating or cooling system for heating or cooling a building space, the system comprising a closed-loop heating or cooling circuit, at least part being located in or adjacent a structural element of the building space, fluid being circulated around the circuit under the control of an energy management controller to heat or cool the building space, and one or more packs containing phase change material located in or adjacent the structural element in heat exchange with the fluid and adapted to heat or cool the building space.
2. A system according to claim 1, wherein the heating or cooling circuit includes a heating or cooling device for heating or cooling the fluid.
3. A system according to claim 2, wherein the heating or cooling device is one of a photovoltaic thermal (PV/T) hybrid panel, a heat pump and a thermal energy store.
4. A system according to any preceding claim, wherein the heating or cooling circuit further comprises a pump for circulating the fluid around the circuit.
5. A system according to claim 4, wherein the pump is operated under the control of the energy management controller.
6. A system according to any preceding claim, wherein the heating or cooling circuit further comprises valves for controlling the movement of the fluid around the circuit.
7. A system according to claim 6, wherein the valves are operated under the control of the energy management controller.
8. A system according to any preceding claim, wherein the heating or cooling circuit further comprises a heating or cooling manifold.

-16 -
9. A system according to claim 8, wherein the manifold includes at least one inlet connected to an outlet of a heating or cooling device by tubing and at least one outlet connected to an inlet of the heating or cooling device.
10. A system according to claim 8 or claim 9, wherein the manifold includes at least one inlet and outlet connected to a tubing loop, at least partly located in or adjacent the structural element.
11. A system according to claim 10, wherein the manifold includes a blending valve for controlling the temperature of the fluid circulated through the tubing loop.
12. A system according to any of claims 8 to 11, wherein the manifold includes a pump for circulating the fluid around the heating or cooling circuit.
13. A system according to claim 12, wherein the pump is operated under the control of the energy management controller.
14. A system according to any preceding claim, further comprising temperature sensors providing temperature information to the energy management controller.
15. A system according to any preceding claim, wherein the heating or cooling circuit is interspersed between neighbouring packs.
16. A system according to any preceding claim, wherein the packs are incorporated into a concrete screed.
17. A system according to any preceding claim, wherein a steel reinforcing mesh is placed on top of the packs.
18. A system according to any preceding claim, wherein the fluid is water or water/glyeol mix. -17-
19. A method of heating or cooling a building space by circulating fluid around a closed-loop heating or cooling circuit, at least part of the circuit being located in or adjacent a structural element of the building space, under the control of an energy management controller, the method comprising the steps of: heating or cooling the fluid before it is circulated through the at least part of the circuit that is located in or adjacent the structural element; transferring heat between the fluid and phase change material located in or adjacent the structural element; and using the phase change material to heat or cool the building space.
20. A method according to claim 19, wherein the phase change material absorbs and stores heat energy from the fluid that has been heated before it is circulated through the at least part of the circuit that is located in or adjacent the structural element and subsequently releases the stored heat energy to provide radiant space heating.
21. A method according to claim 20, wherein the stored heat energy is radiated into the building space through the structural element.
22. A method according to claim 19, wherein the phase change material absorbs and stores heat energy from the building space to provide radiant space cooling and the stored heat energy is subsequently removed from the phase change material by the fluid that has been cooled before it is circulated through the at least part of the circuit that is located in or adjacent the structural element.
23. A method according to claim 22, wherein the heat energy from the building space is absorbed through the structural element.
24. A hydronic radiant heating or cooling system for heating or cooling a building space substantially as described herein and with reference to the drawings.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWSCLAIMSI. A hydronic radiant heating or cooling system arranged to heat or cool a building space, the system comprising: a closed-loop heating or cooling circuit including a tubing loop, at least part of the tubing loop being located in or adjacent a structural clement of the building space, fluid being circulated around the circuit under the control of an energy management controller to heat or cool the building space; one or more packs containing phase change material having a phase change temperature located in or adjacent the structural element in heat exchange with the fluid flowing through the tubing loop and adapted to heat or cool the building space; a primary heating or cooling device arranged to heat or cool the fluid; a thermal energy store; and temperature sensors arranged to provide temperature information to the energy management controller indicative of the measured temperature of the phase change material, and hence its phase state, the measured temperature of the fluid leaving the thermal energy store, and the measured temperature of the fluid leaving the primary heating or cooling device; wherein the heating or cooling circuit further comprises a heating or cooling manifold that includes: a first inlet and outlet connected to the primary heating or cooling device; a second inlet and outlet connected to the thermal energy store; and a third inlet and outlet connected to the tubing loop; and , wherein the energy management controller uses the temperature information *:" 25 provided by the temperature sensors, and the phase change temperature of the phase *:::: change material, to control the circulation of fluid between the primary heating or cooling device and the tubing loop, between the primary heating or cooling device and the thermal energy store, or between the thermal energy store and the tubing loop. * 0 * 0** *: 30 2. A system according to claim 1, further comprising a heat pump connected to the thermal energy store by means of a bypass tubing loop and arranged to extract energy from fluid that is heated or cooled by the thermal energy store and circulated around the bypass tubing loop; wherein the heating or cooling manifold of the heating or cooling circuit further includes a fourth inlet and outlet connected to the heat pump; and wherein the heat pump is arranged to heat or cool the fluid being circulated around the closed-loop heating or cooling circuit.3. A system according to claim 2, wherein the heat pump includes an immersion heater.4. A system according to claim 2 or claim 3, wherein the energy management controller uses the temperature information provided by the temperature sensors to control the circulation of fluid between the thermal energy store and the heat pump through the bypass tubing loop, or between the heat pump and the tubing ioop.5. A system according to any preceding claim, wherein the primary heating or cooling device is a photovoltaic thermal (P'V/T) hybrid panel.6. A system according to any preceding claim, wherein the heating or cooling circuit further comprises a pump arranged to circulate the fluid around the circuit.7. A system according to claim 6, wherein the pump is operated under the control of the energy management controller.*.* .* * * 8. A system according to claim 6 or claim 7, wherein the pump forms part of the manifold. * * * ** I9. A system according to any preceding claim, wherein the heating or cooling circuit further comprises valves arranged to control the movement of the fluid around the circuit, the valves being operated under the control of the energy management controller.10. A system according to any preceding claim, wherein the temperature sensors further provide temperature information indicative of the ambient external temperature and the internal temperature within the building space to be heated or cooled.11. A system according to any preceding claim, wherein the manifold includes a blending valve arranged to control the temperature of the fluid circulated through the tubing loop.12. A system according to any preceding claim, wherein the one or more packs are incorporated into a concrete screed.13. A system according to any preceding claim, further comprising a steel reinforcing mesh on top of the one or more packs.14. A system according to any preceding claim, wherein the one or more packs containing phase change material comprises a plurality of packs containing phase change material, and wherein the tubing loop of the heating or cooling circuit is interspersed between neighbouring packs.15. A system according to any preceding claim, wherein the fluid is water or water/glycol mix.16. A method of heating or cooling a building space by circulating fluid around a closed-loop heating or cooling circuit including a tubing ioop, at least part of the tubing loop being located in or adjacent a structural element of the building space, under the control of an energy management controller, the method comprising the steps of: * using a thermal energy store or a primary heating or cooling device to heat or *:* *: 30 cool the fluid before it is circulated through the tubing loop; transferring heat between the fluid and phase change material having a phase change temperature located in or adjacent the structural element; and using the phase change material to heat or cool the building space; wherein the energy management controller uses temperature information indicative of the measured temperature of the phase change material, and hence its phase state, the measured temperature of the fluid leaving the thennal energy store and the measured temperature of fluid leaving the primary heating or cooling device, and the phase change temperature of the phase change material, to control the circulation of fluid between the primary heating or cooling device and the tubing loop, between the primary heating and cooling device and the thermal energy store, or between the thermal energy store and the tubing loop.17. A method according to claim 16, wherein the phase change material absorbs and stores heat energy from the heated fluid that is circulated through the tubing loop and subsequently releases the stored heat energy to provide radiant space heating.18. A method according to claim 17, wherein the structural element of the building space is located between the phase change material and the building space such that stored heat energy is radiated into the building space through the structural element.19. A method according to claim 16, wherein the phase change material absorbs and stores heat energy from the building space to provide radiant space cooling and the stored heat energy is subsequently removed from the phase change material by the cooled fluid that circulated through the tubing loop. *.OS. * 020. A method according to claim 19, wherein the structural element of the 0::. building space is located between the phase change material and the building space such that heat energy from the building space is absorbed through the structural element. * 0' 00 ** **: 30 21. A hydronic radiant heating or cooling system arranged to heat or cool a building space substantially as described herein and with reference to the drawings.