WO2009053950A2

WO2009053950A2 - A heat transfer system

Info

Publication number: WO2009053950A2
Application number: PCT/IE2008/000101
Authority: WO
Inventors: James Carolan; Gregory Flynn
Original assignee: Kingspan Research And Developments Limited
Priority date: 2007-10-23
Filing date: 2008-10-17
Publication date: 2009-04-30
Also published as: GB0819057D0; GB2454075A; IE20080848A1; WO2009053950A3

Abstract

A building 210 has a plurality of insulating panels including wall panels 21 1 and roof panels 212. At least some of the passageways have passageways therein for a heat exchange medium. A heat transfer system 200 comprises the panels 21 1, 212 and a heat pump 230 which is provided with pre-heated air which has passed through the panels 21 1, 212. Energy is drawn from an output circuit 250 of the heat pump 230.

Description

— i —

"A heat transfer system^"

Introduction

With increasing energy costs there is a need for optimizing heat transfer to and from a building.

This invention is directed towards providing an improved heat transfer system which will address this issue.

Statements of Invention

According to the invention there is provided a heat transfer system comprising a plurality of insulating panels, at least some of the panels comprising a first sheet, a second sheet, and an insulating material therebetween, the insulating panel having a plurality of passageways located adjacent to at least one of the sheets for heat transfer between the sheet and a heat exchange medium in the passageways, and a heater for receiving the heated heat exchange medium from the passageways.

In one embodiment the heat exchange medium is air which may be heated on travel through the passageways of the panels and the pre-heated air from the panels is delivered to a heater.

In one embodiment the air source heater is a heat pump, especially an air source heat pump.

In one embodiment the system further comprises photovoltaic means for providing electrical power to the heat pump. The photovoltaic means may provide electrical power for circulation of a heat exchange medium through the panel passageways. In one case the photovoltaic means comprises a photovoltaic panel and a battery connected to the photovoltaic panel, the battery providing electrical power output. The photovoltaic panel may be a roof panel. The photovoltaic panel may be movable to follow incident solar energy.

O

In one embodiment the heater is an air source heater. The heater may heat pre-heated air delivered to the heater from the panel air passageways.

In one embodiment the system comprises a plenum chamber connected to the panel, the air passageways having an exit opening into the plenum chamber, and the pienum chamber having an outlet for discharge of air which has passed through the air passageways in the panel. In one case the panel has connecting passageways between the panel air passageways and the plenum. The panel air passageways may be located adjacent to a first sheet and the connecting passageways extend through the foam from the panel air passageway through the second sheet. In one case the plenum is attached to the second sheet. Preferably the plenum is sealingly attached to the second sheet.

The system may comprise air drawing means for drawing air into the plenum chamber from the panel air passageway.

In one embodiment the plenum chamber comprises a panel side sub-chamber and a room side sub-chamber and the drawing means draws air from the panel air passageways into the panel side sub-chamber, and air from the panel side sub-chamber into the room side sub-chamber for discharge from the plenum chamber. In one case the plenum chamber is divided into the sub-chambers by a partition wall and the air drawing means is mounted to the partition wall. The air drawing means may comprise a fan. The system may comprise control means for controlling the operation of the air drawing means. In one embodiment the control means comprises a panel air inlet temperature sensor, an air exit temperature sensor and a controller for controlling the operation of the air drawing means in response to the differential between the air inlet and air exit temperatures. There may be a thermostat for activating and/or deactivating the air drawing means.

In one embodiment the system comprises a plurality of insulating panels each having a plurality of air passageways therein and the plenum chamber is connected to a number of adjacent panels. There may be a plurality of plenum chambers. The plenum chambers may be separated.

In one embodiment the air passageways extend longitudinally of the panel.

In one case the panel comprises a barrier between the passageway and the insulating material, especially foam. The barrier may comprise a membrane such as a foil or tape. Preferably the barrier is not planar.

In one case the barrier comprises a pair of longitudinally extending transversely spaced-apart sides defining a plane therebetween and the barrier extends outside of said plane.

In one embodiment the barrier extends into the foam. The barrier may extend inwardly of the first sheet and/or inwardly of the second sheet.

In one embodiment between adjacent air passageways the foam is in direct contact with the sheet(s).

In one case adjacent barriers are spaced-apart.

In one embodiment the first sheet is profiled. Alternatively or additionally the second sheet is profiled.

Preferably the profile defines a profile recess and the recess forms part of the passageway. The passageway may be larger than the profile recess. In one case the passageway comprises the profile recess part and a foam recess part. In one case the foam recess part is oppositely directed with respect to the profile recess part. In one embodiment the foam recess part is of a shape which is substantialiy a mirror image of the profile recess part.

In one embodiment the first sheet comprises a plurality of longitudinally extending profiled crowns, at least some of the crowns defining the passageway. One of the crowns may define an underlap for jointing with an adjacent like panel and the underlap crown is filled with foam.

The panel may be a roof panel, a wall panel, and/or a floor panel.

The invention also provides a building incorporating a heat transfer system of the invention.

Brief Description of the Drawings

The invention will be more clearly understood from the following description thereof given by way of example only, in which :-

Fig. 1 is a perspective view of an insulating panel of the invention;

Fig. 2 is a cross sectional view of the panel of Fig. I ;

Fig. 2(a) is an enlarged view of a barrier used in the panel;

Fig. 2(b) is an enlarged view of a detail of the panel of Figs. 1 and 2; Figs. 3 and 4 are cross sectional views of illustrating an overlap joint between adjacent panels of Figs. I and 2;

Fig. 5 is a perspective view of an apparatus used to manufacture panels of the invention;

Figs. 6(a) to 6(e) are cross sectional views illustrating various steps used in the manufacture of the panels;

Figs. 7(a) to 7(c) are perspective views of an external sheet part of a panel at various stages during the manufacturing process;

Fig. 8 is a cross sectional view of another panel according to the invention:

Fig. 9 is a cross sectional view on an enlarged scale of portions of the panel of₀

Fig. 8;

Fig. 10 is a cross sectional view of a further panel according to the invention;

Fig. 1 1 is a cross sectional view on an enlarged scale of portions of the panel of

Fig. 10;

Figs. 12 to 31 are cross sectional views of various examples of panels according to the invention;

Fig. 32 is a plan cross sectional view of a building comprising a plurality of panels of the invention;

Fig. 33 is a cross sectional view of a top corner of the building of Fig. 32;

Fig. 34 is a cross sectional view of another corner of the building of Fig. 33. Fig. 35 is a perspective view of an insulating panel system of the invention:

Fig. 36 is a perspective view of a plenum chamber detail of the panel system of Fig. 35;

Figs. 37 and 38 are elevational views of the plenum of Figs. 35 and 36;

Fig. 39 is a transverse cross sectional view of a plenum chamber and panel;

Fig. 40 is an enlarged cross sectional view of the insulating panel and plenum system;

Fig. 41 is a perspective view of another insulating panel system of the invention;

Fig. 42 is a perspective view of a plenum chamber detail of the panel system of Fig. 41

Fig. 43 is an elevational view of the plenum system of Fig. 42;

Fig. 44 is a cross sectional view of the plenum chamber of Figs. 41 to 43;

Fig. 45 is a cross sectional view of a roof panel plenum system of the invention;

Fig. 46 is a cross sectional view on the line x-x in Fig. 45;

Fig. 47 is an enlarged view of detail A in Fig. 45;

Fig. 48 is an enlarged view of detail B in Fig. 45; Fig. 49 is a cross sectional view on the line y-y in Fig. 50 of a wall panel plenum system of the invention;

Fig. 50 is a cross sectional view on the line x-x in Fig. 49;

Fig. 51 is a perspective view of a building having a plurality of insulating panels;

Fig. 52(a) is another view of the building of Fig. 51;

Fig. 53 is a diagram of a heat transfer system of the invention;

Fig. 54 is a graph of coefficient of performance of the system at various intake temperatures;

Fig. 55 is a perspective view of another building; and

Fig. 56 is a diagram of another heat transfer system of the invention.

Detailed Description

Referring to the drawings and initially to Figs. 1 and 2 thereof there is illustrated an insulating panel 1 used in the invention comprising a first sheet 2, a second sheet 4 with an insulating body, in this case an insulating foam 5 therebetween. The foam may, for example be a polyisocyanurate foam or a phenolic foam. In this case the panel 1 is a roof panel 1 comprising a profiled external sheet 2 which may be of painted galvanized steel. The profile in this case comprises a plurality of projections, in this case raised crowns 3. The crowns 3 in this case are of generally trapezoidal form and extend longitudinally along the length of the panel. The panel also comprises an inner metal liner sheet 4. The foam defines a plurality of longitudinally extending conduit means 7 through which a suitable heat exchange medium such as air is circulated. The panel thus has an integral heat collecting means provided in some of the crowns 3 of the external sheet which are devoid of insulation 5. The conduits 7 extend through the crowns 3 and air is circulated through the conduits 7. The conduits 7 run through the roof and/or wall in the external envelope of the building and the air absorbs solar energy. Conduits 7 may alternatively or additionally be provided in floor panels for heat circulation. The warmed air may be pumped back into the building to provide heat to the building space. Once the heated air passes through the building and transfers its energy, it may flow back to the conduit in the roof and/or wall and/or floor panels and the process may be repeated in a closed loop.

Barriers, in this case in the form of a membrane such as a tape or foil 10 are located below the crowns 3 to prevent foam entering the crowns 3 and in this case also to create additional foam-free voids below the crowns 3. This creates an enlarged void space through which air may be circulated to enhance the solar collecting efficiency of the panel. Referring in particular to Figs. 2(a) the barriers 10 in this case have projecting side portions or legs 1 1 which may be attached, for example by adhesive to the inner face of the outer skin 3 of the panel. There is a free area 12 between individual barriers 10 to which the foam may directly bond to ensure direct foam bonding to the skin 3. The barriers 10 may be any suitable material such as foil or tape.

In the invention, the barrier 10 is not planar and can be used to define conduits of any desired size and/or shape. The barrier 10 has a pair of longitudinally extending transversely spaced-apart sides, 11 defining a plane therebetween and the barrier extends outside of said plane. The barrier can therefore be extended into the main body of the foam. The barrier can extend inwardly of the first sheet 2 and/or the second sheet 4 to provide a conduit of any desired size and shape. The first and/or second sheets may be profiled and at least some of the profile recesses may form a conduit. To increase the heat transfer capabilities the conduit may be larger than the recess defined by the profile of the sheet. There may be a foam recess part and a profile recess part of the conduit. These may be oppositely directed to enlarge the size of the conduit. In one case the foam recess part is of a shape which is substantially a minor image of the profile recess part.

It will be noted that the cross sectional area of the void space 7 created between the crowns 3 and the barriers 10 is relatively large for optimisation of air flow and heat transfer. Utilising barriers of different size, the void area can be adjusted to suit the particular requirements of a building. In this case an underlap crown 8 is filled with insulation foam so that when overlapped on assembly with an overlap hook 9 of an adjacent panel (see especially Figs. 3 and 4), the panels at the joint can be readily jointed or stitched together. The compressive strength at the joint is enhanced.

Composite panels may be manufactured on a continuous production line by leading the outer sheet 2 along a flat bed with the recesses defined by the crowns 3 facing upwards. The sheet 2 may be of metal such as thin gague steel. The profiled sheet 2 is led to a lay-down area at which liquid foam reactants are spread across the sheet 2 using a lay-down poker or the like. As the foam rises a backing sheet is applied over the foam and the sandwich thus formed is then led through an oven and subsequently cut to length. The backing sheet 3 may be of metal such as thin gague steel. The manufacturing technology is described in our UK-A-2227712, UK-A-2257086, and UK-A-2325640, the entire contents of which are herein incorporated by reference.

In the panels of the invention longitudinal conduit means 7 are defined by the foam.

Referring in particular to Figs 5 to 7 a panel according to the invention is manufactured by leading an external sheet 2 along a flat bed defined by a conveyor having rollers 20. A transverse support 21 is mounted by brackets 22 above the bed. In this case, four anchor blocks 23 are mounted to the support 21 and a former 25 is mounted to each block 23 by screw threaded rods 26. The longitudinal extent of a former 25 may be adjusted by moving the rod 26 relative to the associated anchor block 23. The formers 25 remain static with respect to the moving profiled sheet 2. Barriers which in this case comprise foil strips 10 are applied over the formers 25 and in this case are bonded to the inside face of the sheet 2 on each side of the profiled recess. Adhesive 30 is applied to the inner sheet face by nozzles 31 which are supplied from a supply tank 32. In this case a suitable lubricant 35 is applied to the underside of the barrier strips 10 by brushes 36 supplied from a supply tank 37. The lubricant assists the movement of the barrier strips 10 on the static formers 25. Shaping rollers 40 shape the strips 10 to conform with the exposed profile of the formers 25.

After application of the strips 10 over the formers 25, liquid foam reactants are laid down over the applied barrier strips 10 and the upper face of the sheet 2. A backing sheet 4 is applied and the foam is allowed to expand to fill the space between the sheet 2, barriers 10 and the sheet 4. In this case, the formers 25 only extend for a length sufficient to allow the foam to at least partially set whilst supporting the barrier 10.

The panel with the conduit means defined in the foam continues through an oven to cure the foam. The panels may then be cut to a desired length and various further operations may be performed.

The formers 25 may be of any size and shape and may be located anywhere along a sheet 2 (whether profiled or not). Thus, the method can be utilized to produce a very wide range of panels, including those illustrated by way of example in Figs. 8 to 31. The panels of Figs. 8 to 31 are similar to those of Figs. 1 and 2 and like parts are assigned the same reference numerals.

The panel 100 of Figs. 8 and 9 with two conduits 101 will have the ability to collect and circulate energy but will not be as efficient as the panel of Figs. 1 and 2.

The panel 1 10 of Figs. 10 and 1 1 is similar to that of Figs. 1 and 2. In this case the panel has engagement formations in the form of recesses 1 1 1 and projections 1 12 for engagement of adjacent like panels, lnterengagement features may be provided on any of the panels of the invention.

The panels of the invention may or may not have projections/crowns on their external face. These projections/crowns may or may not be used to provide conduits 7. Using the technology of the invention conduits 7 may be provided in any desired shape at any desired location of the panel.

In the panel 120 of Fig. 12 and the panel 130 of Fig. 13 conduits 7 extend inwardly from the face of the external sheet of the panel. Because the face against which solar energy impinges is generally flat the collection efficiency is likely to be diminished.

The panel 140 of Fig. 14 is similar to that of Fig. 2 except that the crowns/projections 141 are of curvilinear - such as accurate - shape. In the panel 150 of Fig. 15 the crowns/projections 151 are of triangular shape.

The panels 160, 170, 180, 190, of Figs. 16 to 19 are of similar profile and are generally flat with external sheets 2 and/or internal sheets 4 with or without small formations such as microribs.

Referring to Fig. 20, in this case a panel 200 is a roof tile panel with an external sheet of undulating or corrugated form. Panels of this type are described in UK-A -2384500.

The panels 210 and 220 of Figs. 21 and 22 respectively are roof panels of different types incorporating conduits 7.

The panels 230 to 310 of Figs. 23 to 31 respectively again illustrate the application of the invention to a wide range of panel types with different joint details and/or internal sheet and/or external sheet detailing/profiles.

The panels may be used to construct part of or all of the building envelope including the roof, walls and floor. One such building is illustrated in Figs. 32 to 34. Each of the walls and the roof of the building comprise a plurality of the panels 50. Air circulating through the conduit means defined by the foam is directed into ducting 51. The flow or air may be controlled using one or more fans 52. The ducting may have venting system 53 which may be motorized to facilitate ease of operation and control. The circulating air is again heated by solar energy. This hot air is captured and may be passed into the heating/ventilation ductwork of the building, again assisting in heating the building. The heated air may also or alternatively be circulated through a heat exchanger for transfer of solar heat to another heat collector. The system may be set to take air from the warmest or coldest elevations depending on the internal and external temperatures. The system can be used for heating and/or cooling.

Referring especially of Figs. 33 and 34 suitable insulated cappings 55 may be provided. The building may also have insulated flashings 56.

Examples

We have found that the panel of Fig. 2 is particularly suitable for roofs, walls and for floors. The panel has a large exposed surface area and a high large internal void space whilst maintaining structural and insulation properties. The width L of the panel in this case is 1 meter. For optimum thermal efficiency there may be at least three and preferably at least four crowns 3. Each of the crowns 3 defines an area which is devoid of foam.

Referring to Fig. 2(b) the faces that are exposed to the external environment comprise an outer face x and two side faces which diverge inwardly from the outer face x. The angle α between the faces x, y is preferably 1 15 ° to 125°, most preferably 1 18° to 123° and in this case about 121°.

The width wl of the exposed face x is from 50mm to 60mm, most preferably in this case about 54mm. The height hi is from 30mm to 40mm, in this case about 36mm. The total cross sectional area above the dashed line in Fig. 2(b) is about 0.002906m². In this case the cross sectional area is further enlarged by providing an additional recessed section extending into the foam. This additional section has an inner face v and side faces z of which diverge outwardly from the inner face v. The angle α between the faces v and z is preferable 115° to 125°, most preferably 1 18° to 123°, and in this case about 120 .

The inner face v has a width w2 that may be from about 50mm to about 100mm, preferably about 65mm to 75mm, in this case about 70mm. The maximum width w3 of the cavity is in this case about 80mm to 120mm, preferably about 90mm to 1 10mm and in this case about 97mm.

The depth h2 of the recessed section is typically from 10mm to 40mm, preferably 20 to 35mm, and in this case about 27mm.

The cross sectional area of the recessed section below the dashed line is about 0.00236m².

The total cross sectional area of the cavity (void area) is 0.002906 + 0.00236 = 0.005266m²

The efficiency is calculated based on an air velocity through the cavity of 4.3m/s, operating through an elevation of 6m xlOOm.

The ASHRAE Standard 93-2003-equation for efficiency of a solar collector

n =

A-I

Test data generated using the panel of Fig. 2 indicates an approximately 9.5 deg C air temp rise at 500W/m"

The energy production possible the panel was calculated using RETscreen International Clean Energy Project Analysis software available at www.retscreen.net. The following assumptions were made: Building Location: North West England

Building Size: 1 Om x 100m x 100m - 10,000m² floor space.

South Facing Wall: 100m (W) x 10m (H)

Fan Air Speed: 7m / sec.

Using the panels of Figs. 1 and 2 to construct the south facing wall of the building and circulating air through the foam-free passageways results in the following energy production:

Renewable heating energy delivered in one year 183.08 MWhrs based on local wather data.

Referring to Figs. 35 to 40 there is illustrated a heat transfer system according to the invention comprising a plurality of insulating panels 60 which in this case are similar to the panels described above with reference to Figs. 1 to 4 and like parts are assigned the same reference numerals. A building is at least partially constructed from a plurality of the panels 60. Each of the panels 60 has a plurality of air passageways 7 therein. The system comprises plenum chambers defined by housings 61 into which air from the panel passageways is drawn. Only one such housing 61 is illustrated however several such housings may be provided at appropriate locations associated with the same or different groups of panels 60. Some of the plenums have been omitted in Fig. 35 for illustrative purposes. The housings 61 have outlets 62 for discharge of air.

In this case the backing sheet 4 of the panel and the foam 5 have connecting passageways 65 therein through which air is drawn from the panel passageways 7 into the housing 61 which in this case is attached to the backing sheet 4.

Plenum housings 61 of varying lengths (dependant on building design) span across the passageways 65. Expandable foam tape is applied around the perimeter of the plenum housing 61 to ensure sealing between the plenum and profiled liner tray 4. The plenum 61 may be pop riveted to the liner tray 4. Alternatively or additionally the housing 61 may be braced to support the steelwork, if required.

The plenum chamber 61 comprises a panel side sub-chamber 70 and a room side sub- chamber 71 which are divided by a partition wall 72. Drawing means in this case a fan 73, is mounted to the partition wall 72 and draws air from the panel air passageways 7 into the panel side sub-chamber 70 and into the room side sub-chamber 71 for discharge through the outlets 72.

The system comprises control means for controlling the operation of the fan 73 and hence the flow of air from the panels 50 into the room. The control means comprises a panel air inlet temperature sensor, an air exit temperature sensor and a controller for controlling the operation of the fan 73 in response to the differential between the air inlet and air exit temperatures. There is also a thermostat for activating or de- activating the fan 73.

When the fan 73 is activated it creates a uniform negative pressure across the sub- chamber 70, ensuring that an equivalent/balanced air flow through each passageway 7 is achieved. Warm air entering the sub-chamber 70 is drawn into the room side sub- chamber 71 creating an overall positive pressure. There is a pressure differential between the room side sub-chamber 71 and the internal building environment, forcing air to flow out of the plenum through gravity backdraught vents 75.

A thermostat communicates to the fan control system when the interna! building temperature falls outside the desired range. This will in turn activate the fans 73 which will draw air through the crowns/heat exchanger passageways 7 into the plenum

61 delivering heated fresh air to the building. In the event of low levels of solar radiance, whereby the surface temp of the panel is not adequate to heat the air to the required temp, an internal sensor encapsulated in the plenum senses the cold air drawn into plenum and deactivates the fan 73.

Referring to Figs. 41 to 44 there is illustrated another heat transfer system of the invention which is similar to that described with reference to Figs. 35 to 40 and like parts we assigned the same reference numerals. In this case a plenum chamber is defined by a plurality of channel section housings 77 which are interengagable and interlockable together. The housing 77 has a male projection 78 at one end for engagement with a corresponding recess 79 of an adjacent housing 77 may be readily assembled. A fan 73 is housed in a fan housing 80 which is fixed to the housing 77. In this case side outlets 81 are provided for discharge of air from the fan housing 80. This system is particularly useful as it is modular, lightweight and easy to fit. The plenum housing sections 77 comprise an insulation material to insulate the plenum and prevent cold bridging. Each section 77 may comprise a metal (such as steel) facing with an insulation material (such as an insulation foam board) bonded thereto. Alternatively the housing section 77 may be formed from a unitary material such as plastics which may be vacuum formed.

A roof panel plenum system is illustrated in Figs. 45 to 48. This incorporates the modular assembly system as described with reference to Figs. 41 to 44 and like parts are assigned the same reference numerals. The panels 60 and modular housing sections 77 are used to build up a heat transfer system, as illustrated. Ends of a run of housings 77 may be closed off with an end wall 83. Figs. 49 and 50 illustrate a wall plenum system of the invention which is similar to the roof plenum system described above and like parts are assigned the same reference numerals. In this case fan housing outlets 84 are provided on a front wall of the fan housing 80. Using wali panels is preferred because they provide for efficient solar energy collection, even in winter months when the sun is low.

Two temperature sensors are incorporated into the control system one in the plenum, measuring air intake temperature, and one externally measuring the temperature of the air entering the panel. This temperature differential dictates the speed at which the fan/fans 73 operate. For example in the morning when the sun is rising the surface temperature of the metal begins to heat up, subsequently warm air is drawn through the system slowly to ensure maximum heat transfer, hence is delivered to the building at a slow rate. As the temperature of the metal increases so to does the fan speed until the fan reaches full power.

The fans 73 continue to run at an optimal speed, dictated by the temperature differential, until either the thermostat or low levels of radiation deactivate the system.

It will be appreciated that the heat exchange system can be used in association with any suitable panel containing air passageways. Several non-limiting examples are illustrated in Figs. 8 to 31.

Referring to Figs. 51 to 54 there is illustrated a heat transfer system 200 and a building 210 both according to the invention.

Referring to Figs. 51 and 52 the building 210 has a plurality of insulating panels including wall panels 21 1 and roof panels 212. At least some of the panels have passageways therein for a heat exchange medium. For example, the panels are preferably of the type described above with reference to Figs. 1 to 50 with air passageways through which air is circulated as described. One such panel are those illustrated in Figs. 1 to 4.

The heat transfer system 200 of the invention includes the panels 21 1, 212 of the building 210. The system also comprises a heat pump 230 having a heat transfer circuit with an evaporator 231 , a compressor 232, a condenser 233 and an expansion valve 234. Input energy can be provided through one or more of the earth 235, air 236, or water 237. In this case the primary input is pre-heated air which has passed through the panels 21 1, 212 and transfer is effected by a loop 240 through which a heat transfer medium is circulated by a pump 241. Heat is transferred to the evaporator 231 of the heat pump and output from the condenser 233 of the heat pump is by way of a heat transfer output circuit 250 with a pump 251. Energy is drawn from the output circuit 250, for example to heat radiators 252 or the like heat output.

It will be apparent from the graph of Fig. 54 that the coefficient of performance is much higher when air which is pre-heated by passage through the insulating panels 211 is used. The efficiency is greatly enhanced over using ambient air input, especially during cold air temperature conditions. The heat pump can typically heat water to 35⁰C which in turn can heat an under-floor heating system or a fan-coil type heater.

An alternative heat transfer system 400 is illustrated in Fig. 56. This is similar to the system of Fig. 38 and like parts are assigned the same reference numerals. A building 410 used with the system 400 in this case has photovoltaic panels 41 1 which in this case are located on the roof of the building. The photovoltaic panels 41 1 are used to change a battery pack 420 which provides electrical power to the heat pump 230 and may power fans 421 used to circulate air through the panels 21 1. Such a building may be energy self-sufficient.

Alternatively or additionally the preheated air from the panel air passageways may be utilised as a source for any suitable heater such as a space heater or the like which may be a stand alone unit or may be integrated into a building heating system. Many variations on the embodiments described will be readily apparent. Accordingly the invention is not limited to the embodiments hereinbefore described which may be varied in detail.

Claims

1. A heat transfer system comprising a plurality of insulating panels, at least some of the panels comprising a first sheet, a second sheet, and an insulating material therebetween, the insulating panel having a pluraiity of passageways located adjacent to at least one of the sheets for heat transfer between the sheet and a heat exchange medium in the passageways, and a heater for receiving the heated heat exchange medium from the passageways.

2. A system as claimed in claim 2 wherein the heat exchange medium is air which is heated on travel through the passageways of the panels and the preheated air from the panels is delivered to the heater.

3. A system as claimed in claim 1 or 2 wherein the heater is a heat pump.

4. A system as claimed in any of claims 1 to 3 further comprising photovoltaic means for providing electrical power.

5. A system as claimed in claim 4 wherein the photovoltaic means provides electrical power for circulation of a heat exchange medium through the panel passageways.

6. A system as claimed in claim 4 or 5 wherein the photovoltaic means comprises a photovoltaic panel and a battery connected to the photovoltaic panel, the battery providing electrical power output.

7. A system as claimed in claim 6 wherein the photovoltaic panel is a roof panel.

8. A system as claimed in claim 6 or 7 wherein the photovoltaic panel is movable to follow incident solar energy.

9. A system as claimed in any preceding claim wherein the heater is an air source heater.

10. A system as claimed in claim 9 wherein the heater heats pre-heated air delivered to the heater from the panel air passageways.

1 1. A heat transfer system as claimed in any of claims 1 to 10 comprising a plenum chamber connected to the panel, the passageways having an exit opening into the plenum chamber, and the plenum chamber having an outlet for discharge of air which has passed through the air passageways in the panel.

12. A system as claimed in claim 1 1 wherein the panel has connecting passageways between the panel air passageways and the plenum.

13. A system as claimed in claim 12 wherein the panel air passageways are located adjacent to a first sheet and the connecting passageways extend through the foam from the panel air passageway through the second sheet.

14. A system as claimed in claim 13 wherein the plenum is attached to the second sheet.

15. A system as claimed in claim 14 wherein the plenum is sealingly attached to the second sheet.

16. A system as claimed in any of claims 1 1 to 1 5 comprising air drawing means for drawing air into the plenum chamber from the panel air passageway.

17. A system as claimed in any of claims 1 1 to 16 wherein the plenum chamber comprises a panel side sub-chamber and a room side sub-chamber and the drawing means draws air from the panel air passageways into the panel side sub-chamber, and air from the panel side sub-chamber into the room side sub- chamber for discharge from the plenum chamber.

18. A system as claimed in claim 17 wherein the plenum chamber is divided into the sub-chambers by a partition wall and the air drawing means is mounted to the partition wall.

19. A system as claimed in any of claims 16 to 18 wherein the air drawing means comprises a fan.

20. A system as claimed in any of claims 16 to 19 comprising control means for controlling the operation of the air drawing means.

21. A system as claimed in claim 20 wherein the control means comprises a panel air inlet temperature sensor, an air exit temperature sensor and a controller for controlling the operation of the air drawing means in response to the differential between the air inlet and air exit temperatures.

22. A system as claimed in claim 20 or 21 comprising a thermostat for activating and/or de-activating the air drawing means.

23. A system as claimed in any of claims 1 1 to 22 comprising a plurality of insulating panels each having a plurality of air passageways therein and the plenum chamber is connected to a number of adjacent panels.

24. A system as claimed in claim 23 comprising a plurality of plenum chambers.

25. A system as claimed in claim 24 wherein the plenum chambers are separated.

26. A system as claimed in any of claims 1 1 to 25 wherein the air passageways extend longitudinally of the panel.

27. A system as claimed in any of claims 1 to 26 comprising a barrier between the passageway and the insulating material.

28. A system as claimed in claim 27 wherein the barrier comprises a membrane such as a foil or tape.

29. A system as claimed in claim 27 or 28 wherein the barrier is not planar. ^■

30. A system as claimed in any of claims 27 to 29 wherein the barrier comprises a pair of longitudinally extending transversely spaced-apart sides defining a plane therebetween and the barrier extends outside of said plane.

31. A system as claimed in any of claims 27 to 30 wherein the barrier extends into the insulating material.

32. A system as claimed in any of claims 27 to 31 wherein the barrier extends inwardly of the first sheet.

33. A system as claimed in any of claims 27 to 31 wherein the barrier extends inwardly of the second sheet.

34. A system as claimed in any of claims 27 to 33 wherein between adjacent air passageways the foam is in direct contact with the sheet(s).

35. A system as claimed in claim 33 wherein adjacent barriers are spaced-apart.

36. A system as claimed in any of claims 1 to 35 wherein the first sheet is profiled.

37. A system as claimed in any of claims 1 to 36 wherein the second sheet is profiled.

38. A system as claimed in claim 36 to 37 wherein the profile defines a profile recess and the recess forms part of the passageway.

39. A system as claimed in claim 38 wherein the passageway is larger than the profile recess.

40. A system as claimed in claim 38 or 39 wherein the passageway comprises the profile recess part and an insulation recess part.

41. A system as claimed in claim 40 wherein the insulation recess part is oppositely directed with respect to the profile recess part.

42. A system as claimed in claim 41 wherein the insulation recess part is of a shape which is substantially a mirror image of the profile recess part.

43. A system as claimed in any of claims 1 to 42 wherein the first sheet comprises a plurality of longitudinally extending profiled crowns, at least some of the crowns defining the passageway.

44. A system as claimed in claim 43 wherein one of the crowns defines an underlap for jointing with an adjacent like panel and the underlap crown is filled with insulation.

45. A system as claimed in any of claims 1 to 44 wherein the panel comprises a roof panel.

46. A system as claimed in any of claims 1 to 45 wherein the panel comprises a wall panel.

47. A system as claimed in any of claims 1 to 46 wherein the panel comprises a floor panel.

48. A heat transfer system substantially as hereinbefore described with reference to the accompanying drawings.

49. A building incorporating a heat transfer system as claimed in any preceding claim.