Building Construction
Accordingly, this invention provides a method for constructing a building, the method comprising: (i) providing a supporting framework; (ii)providing at least one power generation member (10), the power generation member (10) comprising, in a discrete unit, a first layer and a second layer, wherein the first layer comprises support material (30, 32, 34) and the second layer comprises at least one energy converter for converting solar energy into heat and/or electricity (12, 14); and (iii) attaching the power generation member (10) to the framework such that the power generation member (10) is substantially self supporting and provides an outer surface of the building.
This invention relates to a method and device for constructing a building, in particular one that simultaneously provides weather protection, insulation and solar energy capture (heat and/or power).
BACKGROUND TO THE INVENTIONWith rising concerns over emissions of carbon dioxide and the increasing scarcity of fossil fuels it is becoming ever more difficult and expensive to rely upon these resources as a source of electricity. Therefore a growing market has been established for the exploitation of renewable resources. Solar power represents one of the most mature technologies for exploiting the natural resources available to us, and is therefore growing in popularity. However, it is difficult to build monolithic solar power plants which produce power comparable to traditional fuel-burning plants, because of the large area of solar panels that is required to achieve this output. One way to overcome this problem is to use small installations of solar panels in many locations, such as on rooftops. These solar panels can then be used to generate electricity, or to capture heat from the sun, for example. Solar panels are often difficult to fit, being generally fragile. A method which allowed solar power to be incorporated quickly and easily into buildings would therefore be extremely desirable.
SUMMARY OF THE INVENTIONAccordingly, this invention provides a method for constructing a building, the method comprising:
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- (i) providing a supporting framework;
- (ii) providing at least one power generation member, the power generation member comprising, in a discrete unit, a first layer and a second layer, wherein the first layer comprises support material and the second layer comprises at least one energy converter for converting solar energy into heat and/or electricity; and
- (iii) attaching the power generation member to the framework such that the power generation member is substantially self supporting and provides an outer surface of the building.
In this way the invention provides a simple and effective method for constructing a building using parts which act as structural components as well as providing heat and/or electricity. Power generation members according to the invention can be manufactured off-site as complete integrated panels, before being taken to the construction site and simply fastened in place to form a wall or roof. Thus the method of the invention combines a solar panel with a roof or wall panel to greatly simplify the construction process and can also provide weather protection and insulation. It can replace rafters, panelling, insulation and roof covering along with many other components typically found in building construction. By incorporating energy converter in this way, the structural components of the building also act to support the energy converter, removing the need for a second support. All of these features offer large savings in both build time and cost of materials.
The framework may comprise wood, steel, concrete, plastic, glass reinforced plastic or any other suitable material or combination of materials. Typically, the framework may be the A-frame of a roof. The framework may also be the inner walls of a building.
Typically, the energy converter may comprise a photovoltaic device, for example a thin film semiconductor device. Crystalline, thin film and die solar cells may all be used, for example. The energy converter may comprise at least one thermal collector, for example in addition to a photovoltaic device. In one embodiment, the power generation member comprises a third layer comprising at least one thermal collector, the third layer being secured between the first and second layers. Alternatively, the third layer may be substantially transparent and secured over the first layer; in this embodiment fluid will typically be passed through the third layer so that heat may be absorbed from the first layer. A thermal collector may both help to keep the photovoltaic devices cool and can be used to heat water, air or any other desired substance for subsequent use in and around the building, or for evaporative cooling.
In the presently preferred embodiment, the thermal collector comprises at least one metal pipe, the pipe being filled with a fluid in use, typically water. Alternatively, the pipe may be substantially evacuated in use except for an amount of a fluid such as water much smaller in volume than the inner volume of the pipe, when condensed. Alternatively, the thermal collector may simply comprise a pipe containing a suitable thermally conductive fluid, such as water, glycol, ammonia and the like.
The pipe may be straight, in which case a large number of parallel pipes will typically be used to cover the area beneath the photovoltaic device. Alternatively, a smaller number of pipes which curve or bend may be used to cover the same area.
Typically, the thermal collector comprises a flat plate, which may further comprise channels therein for the passage of fluid, which is extruded in manufacture so that it can readily be produced in the desired length, or cut to length subsequently. The extrusion can then be capped and sealed at either end by end caps designed to collect the fluid and direct it as required. Alternatively, flat plate collectors can be made from bonded or welded sheet metal and connected in the same manner. The thermal collector could also comprise an absorber plate with either (i) a coil/pipe or (ii) a heat pipe welded or bonded to its rear.
Metals are preferred for the thermal collector because of their high thermal conductivity. However, any thermally conductive material could be used. Conductivity is improved where the thickness of material is small. In some embodiments, a plastic membrane suffices to allow rapid conduction of heat to the transmission fluid. Water is preferred for the transmission fluid because of its high heat capacity, which allows a small amount of water to be used to move a large amount of heat, reducing the amount of energy wasted in conveying the heat to its eventual destination. However, other substances which are liquid or gaseous at suitable temperatures and pressures, such as glycol or air, could be used.
As well as pipes, solid heat conductors could also be used. For example, metal fins could be used to conduct heat to a desired destination, such as a reservoir of water at one end of the power generation member.
Typically, the power generation member further comprises a protective layer which may be transparent. The protective layer may be secured over the energy converter. The protective layer may comprise at least one layer of sheet metal, glass, for example low iron or low e glass, plastic or other transparent or translucent materials. Low iron glass is favoured because it has good transmittance characteristics in the solar spectrum. The transparent protective member may also comprise a low emissivity coating. Low emissivity glass and other similar materials are useful because they can reflects much of the infra red radiation emitted within the power generation member, helping the member to maintain its temperature where this is desirable. In some instances, it may be possible that the solar energy converter is embodied in the protective layer.
The protective layer can both protect the energy converter and help to retain heat for the thermal collector. There may be a space between the protective layer and the photovoltaic device which can, for example, be evacuated or filled with argon, carbon dioxide, or some other light transmitting, insulating material or gas to further increase the retention of heat. In any event the power generation member should preferably form a sealed unit. The interior of the power generation member may be provided with inhibitors to prevent a build-up of water vapour and/or microbes. Air glass may be used to fill any space in the power generation member.
The method may further comprise:
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- (iv) providing a dummy member, the dummy member comprising a first layer which is a support member and a covering so that it resembles the power generation member; and
- (v) attaching the dummy member to the framework such that the dummy member is substantially self supporting and provides an outer surface of the building.
The use of a dummy member allows the entire surface of the building to be constructed from matching panels, even where energy converters are not required.
Typically the support member comprises an insulating material of low thermal conductivity. The insulating material may be a mineral wool, a plastic such as polystyrene or polyurethane foam, a plant or animal product such as cellulose or sheep's wool, or any other suitable material. This will provide insulation for the building. Polyurethane can also provide structural rigidity and sealing of the power generation member. The support member will usually comprise insulating material laid within a structure formed from a supporting material, such as wood, metal, concrete, plastic, glass reinforced plastic or any other suitable material.
A method as claimed in any preceding claim, further comprising the step of cutting the power generation member to a length that fits the supporting framework. Thus, the pre-fabricated power generation member may be cut to length in situ or when fabricated. In this case, end caps may be provided to seal one or both ends of the power generation member. Such end caps may provide electrical and/or fluid connections to the energy converter. Where a thermal collector is formed from a plurality of parallel channels, an end cap may be provided to connect adjacent channels, whereby to form a serpentine fluid pathway.
The invention further provides a power generation member as described above, and a dummy member as described above.
The invention also provides a device for converting solar energy to heat, the device comprising:
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- a substantially prismatic member, having defined therein plurality of substantially parallel channels; and
- at least a first end piece suitable for attaching to the member whereby the channels are brought into fluid communication via the end piece.
In this way, the invention provides a device which can be manufactured using standard processes and at standardised lengths, but which can then be reduced to any desired length by cutting the parallel channels and attaching the end piece. Once the desired length has been achieved the device can be installed and a fluid passed through the channels so that it is heated by solar energy. Where the ambient temperature is lower than the temperature in the channels, it would be possible for a device according to the invention to function as a radiator. In one embodiment, it is also possible to adjust the size of the device along another axis by cutting off some of the parallel channels completely, provided that the end piece is also cut to match.
Typically, the member will be formed as an extrusion.
In one embodiment of the invention, at least two of the plurality of parallel channels are connected via the first end piece, in use, so as to form a continuous channel.
Typically, the device comprises a second end piece suitable for attaching to the channels such that the channels are connected through the end piece. In use, the first end piece is then attached to one end of a channel and the second end piece is attached to the other end of that channel.
Typically, the device comprises a second end piece suitable for attaching to the member whereby the channels are brought into fluid communication via the end piece. In use, the first end piece is attached to one end of the member and the second end piece is attached to the other end of the member.
An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:
The PV cells 12 are thin film semiconductor cells which use a thin layer of amorphous silicon to generate electricity from sunlight. These cells 12 are produced in a flexible sheet and can easily be used to cover a large area. Their flexibility means that embodiments of this invention can be produced with curved surfaces if desired. The first heat exchanger 14 is produced by extrusion, and it can also be shaped when curved embodiments of the invention are required.
There are several parallel channels 24 set into the first heat exchanger 14. In use, the channels 24 are filled with water. When sunlight is shining on the first solar device 10, the PV cells 12 are heated up and this thermal energy is conducted through the adhesive layer 16 to the first heat exchanger 14. The water in the channels 24 absorbs the heat. This has two advantages. Firstly, the PV cells are cooled and can therefore work more efficiently. Secondly, the heated water in the channels 24 can be pumped out of the first solar device 10 for use. In order to avoid breaking the seal which maintains the low pressure in the channels 24, the heated water will usually be pumped through a sealed coil inside a tank which contains more water, which will then be heated by conduction. This will serve to cool down the water from the first solar device 10 before it is returned to the channels 24.
The sheet of glass 20 helps to prevent the loss of heat due to convection, and hence ensures that hotter water is produced by the first heat exchanger. Low iron glass is used for the sheet of glass 20 because it provides good light transmittance at a wide range of frequencies. The space 26 between the glass and the PV cells is filled with argon. Argon is used because it is inert, largely transparent and has very low thermal conductivity. A sealant 28 is provided around the spacer bars 22 in order to prevent the argon leaking
The support member 18 is composed of two parts, an inner core of insulating material 30 and an outer layer of stiffening material 32, 34. The inner core 30 is polyurethane foam which provides insulation for a building constructed using the first solar devices 10, as it has very low thermal conductivity. In particular, the used of insulation reduces the heat loss that might otherwise occur through the metal components in and surrounding the PV cells 12. In operation, this low conductivity also helps to reduce heat loss from the first heat exchanger 14 and provides insulation to the building. Other insulating materials can be used, and set such that building codes are complied with. The outer layer comprises two rafters 32 fixed to a facing board 34, and serves to protects the inner core 30 and strengthens the support member 18 so that the member can act as a support for the rest of the first solar device 10. As can be seen in
The facing board 34 used in the first solar device 10 is of a suitable quality and appearance that it can be left as the inner surface of a roof or wall if desired. However, inner facings such as plasterboard, timber, or soundproofing materials can easily be fitted in addition or as an alternative when required.
The dummy solar device 40 is intended for use in buildings that also use the first solar device 10. The dummy solar device 40 is a cheaper and less delicate than the first solar device 10, and is therefore suitable for use on sections of wall or roof which do not receive enough sunlight to make the use of a first solar device 10 cost efficient. This allows the building to posses a uniform appearance without sudden jarring changes of texture between, for example, the north and south facing walls.
In use, both the first solar device 10 and the dummy solar device 40 are typically fastened to a conventional framework of wooden beams, concrete, steel or any other suitable material to form part of a roof or wall in the building which is being constructed. The device provides external weather proofing, insulation and outerleaf structural elements as well as providing a means for converting solar energy to heat or power.
Furthermore, the space 96 between the glass 20 and the PV cells 12 of the third solar device 90 is evacuated to minimise heat loss rather than being filled with argon.
Although thin film semiconductor PV cells 12 are used in the embodiments described above, other solar to power conversion technologies can be used. For example, crystalline silicon cells may be used. Similarly, the transparent protective sheet 20 need not be low iron glass, which is expensive. Other protective covers can be used, such as polycarbonate.
The heat exchanger 14 described above uses water contained in channels to transport heat. However, other types of heat exchangers, such as fin, coil or heat pipe heat exchangers, can be used. The heat exchanger may also combine different techniques to transport the heat as desired. Where a fluid medium is used to transport the heat, that fluid will typically be water, but it may be some other suitable substance.
In the embodiments shown in
In summary, this invention provides a method for constructing a building, the method comprising:
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- (i) providing a supporting framework;
- (ii) providing at least one power generation member 10, the power generation member 10 comprising, in a discrete unit, a first layer and a second layer, wherein the first layer comprises support material 30, 32, 34 and the second layer comprises at least one energy converter for converting solar energy into heat and/or electricity 12, 14; and
- (iii) attaching the power generation member 10 to the framework such that the power generation member 10 is substantially self supporting and provides an outer surface of the building.
Claims
1. A method for constructing a building, the method comprising:
- (i) providing a supporting framework;
- (ii) providing at least one power generation member, the power generation member comprising, in a discrete unit, a first layer and a second layer, wherein the first layer comprises support material and the second layer comprises at least one energy converter for converting solar energy into at least one of heat and electricity; and
- (iii) incorporating the power generation member to the framework such that the power generation member acts as a substantially self supporting load bearing structure of the building and provides an outer surface of the building as well as generating power.
2. A method as claimed in claim 1, wherein the energy converter is a photovoltaic device.
3. A method as claimed in claim 2, wherein the photovoltaic device comprises a thin film semiconductor device.
4. A method as claimed in claim 1, wherein the energy converter comprises at least one thermal collector.
5. A method as claimed in claim 1, wherein the power generation member further comprises a transparent protective layer, the protective layer being secured over the energy converter.
6. A method as claimed in claim 5, wherein the transparent protective member comprises at least one layer of low iron glass.
7. A method as claimed in claim 5, wherein the transparent protective member comprises a low emissivity coating.
8. A method as claimed in claim 1, wherein the support material comprises an insulating material of low thermal conductivity.
9. A method as claimed in claim 1, wherein the method further comprises:
- (iv) providing a dummy member, the dummy member comprising a first layer which is a support member and a covering so that it resembles the power generation member; and (v) attaching the dummy member to the framework such that the dummy member is substantially self supporting and provides an outer surface of the building.
10. A method as claimed in claim 1, further comprising the step of cutting the power generation member to a length that fits the supporting framework.
11. (canceled)
12. (canceled)
13. A device for converting solar energy to heat, the device comprising:
- a substantially prismatic member, having defined therein plurality of substantially parallel channels; and
- at least a first end piece suitable for attaching to the member whereby the channels are brought into fluid communication via the end piece.
14. A device as claimed in claim 13, the member being formed as an extrusion.
15. A device as claimed in claim 13, wherein at least two of the plurality of parallel channels are connected via the first end piece, in use, so as to form a continuous channel.
16. A device as claimed in claim 13, wherein the device comprises a second end piece suitable for attaching to the member whereby the channels are brought into fluid communication via the end piece,
- wherein, in use, the first end piece is attached to one end of a channel and the second end piece is attached to the other end of that channel.
17. A structural unit for a building comprising at least one power generation means, adapted at a first end for connection to a framework and adapted at the other end for connection to an upper structure, wherein, when connected, the power generation member extends from the framework to the upper structure and forms at least part of the outer surface of the building and acts as a substantially self supporting load bearing structure of the building and provides weather proofing to the building as well as generating power.
18. A structural unit according to claim 17, wherein the structural unit is a roof member for a building, adapted at the first end for connection to a substantially vertical wall and adapted at the other end for connection to a capping piece, wherein, when connected, the roof member extends from the wall to the capping piece and forms at least part of the roof structure.
19. A structural unit according to claim 18, wherein the roof member comprises an insulation layer so that, when in use, the roof member provides insulation to the building.
20. A structural unit according to claim 17, wherein the unit is a wall member for a building, adapted at a first end for connection to at least one of a wall and a foundation and adapted at the other end for connection to a top piece, wherein, when connected, the wall member extends from the wall to the top piece and forms at least part of the wall structure.
21. A structural unit according to claim 20, wherein the top piece is one of a wall and a roof structure.
22. A structural unit according to claim 20, wherein the wall member includes an insulating material of low thermal conductivity.
Type: Application
Filed: Sep 18, 2009
Publication Date: Oct 13, 2011
Inventor: Richard David Bankart (London,)
Application Number: 13/119,421
International Classification: E04D 13/18 (20060101); F24J 2/42 (20060101); E04H 14/00 (20060101);