WO1995004006A1

WO1995004006A1 - Solar energy glazing systems and methods

Info

Publication number: WO1995004006A1
Application number: PCT/GB1994/001621
Authority: WO
Inventors: Frederick Brian Mckee
Original assignee: Frederick Brian Mckee
Priority date: 1993-07-28
Filing date: 1994-07-27
Publication date: 1995-02-09
Also published as: GB2280503B; AU7347394A; GB9415151D0; GB2280503A; GB9315584D0

Abstract

In one of its aspects the invention provides for the coating or doping of glazing panels or a fluid filled solar panel (40) the combined optical transmission qualities of the constituent parts of which permit transmission of light highly visible to the human eye, but which provide absorption of solar energy outside that spectrum. In another of its aspects the first aspect may form a part of a glazing system having two or more generally parallel panes or panels (13, 40) housed within a vented framework (11, 12, 19-22) to provide at least one vented air-space (15) therebetween. At least one of the panes or panels (40) is adapted to absorb solar energy and thereby 'heat' the air contained within the air-space (15) to cause convection currents therein. Inlet vents (20, 22) and outlet vents (19, 21) are respectively disposed above and below each of the panes or panels (13, 40) and by appropriate control of these it is possible to use the convection currents within the air-space (15) to vent air into or out of the building interior or to vent the air-space (15) externally of the building to cool the said at least one pane or panel (40).

Description

SOLAR ENERGY GLAZING SYSTEMS AND METHODS

This invention relates to solar energy glazing systems and use thereof generally and more particularly, but not exclusively, to solar energy glazing adapted to transmit therethrough only useful wavelengths of solar energy and/or to distribute by convection/conduction heat absorbed by panels of the glazing.

One of the major problems with large buildings is to reduce the heat gain due to incident solar and other energy incident on the building. Also, it is often desirable to reduce the heat escaping frcm the building in cold periods. One solution is to use heavily tinted or reflective glass often as part of a double-glazing system. Tinted glass tends to be heated by incident solar radiation thereby radiating that energy into the building at wavelengths iininhibited by the tinting agent. Reflective glass may not be aesthetically pleasing and during winter months the reflected energy could more usefully be used for heating the building interior.

In addition tinted and reflective glazing greatly restricts the visible natural daylight entering the building. This often necessitates the use of electrical lighting in day-time even during suππer months.

It is an object of the invention to provide an improved form of glazing.

In accordance with a first aspect of the invention a glazing system comprises a pane of transparent or translucent material and a doping agent and/or coating agent the ccπibined optical characteristics of the system providing solar energy transmission therethrough having a transmission curve closely approximating the photopic response function CTE 18(E-1.2)1970 of the human eye.

In accordance with a second aspect of the invention a glazing system comprises a pane of transparent or translucent material and a doping agent and/or coating agent applied to one surface of the pane the ccπibined optical characteristics of which permit light -transmission through the system of the majority of wavelengths of solar energy visible to the human eye and which provide for absorption by the glass and the coating of the majority of solar energy invisible to the human eye.

The doping agent and/or coating agent may be pthylocyanine and may have a concentration in a range equivalent to between 40 and preferably approximately 80 pp in aqueus solution.

In accordance with a third aspect of the invention a solar energy collecting panel comprises two panes of glass or generally transparent plastics and at least one fluid passageway therebetween with a solution of dyestuff contained within the passageway, with the arrangement providing that the combined optical characteristics of the panel provide solar energy transmission therethrough having a transmission curve closely approximating the photopic response function CTE 18(E-1.2)1970.

In accordance with a fourth aspect of the invention a solar energy collecting panel comprises two panes of glass or generally transparent plastics and at least one fluid passageway therebetween with a solution of dyestuff contained within the passageway, with the arrangement providi-ng that the cαiibined optical characteristics of the panel permit light transmission through the panel of the majority if not all wavelengths of solar energy visible to the human eye and which provide for -absorption by the glass and the coating of the majority of solar energy invisible to the human eye.

A solar panel in accordance with said third or fourth aspect of the invention, wherein the dyestuff may be water soluble pthylocyanine which may have a concentration in the range of 30 to 200 ppm, preferably in the range of 60 to 80 ppm. It may have a concentration in the order of 40 ppm.

According to a fifth aspect of the invention a vented windcw apparatus comprises a frame housing in spaced apart relationship a first pane of generally transparent glass or plastics and a first glazing system in accordance with said third aspect or said fourth aspect to define an air-space therebetween, having disposed above said first pane a first closable outlet vent, below said first pane a first closable inlet vent, above said first system or panel a second closable outlet vent and below said first system or panel a second closable inlet vent, with the arrangement providing that solar energy absorbed by said first pane, system or panel can be removed by convection of air through the air-space when one, other or both of said first inlet vents is or -are open and one, other or both of said first outlet vents is or are open.

-According to a sixth aspect of the invention a method of heating a building has apparatus in accordance with said fifth aspect with said first pane exposed internally of the buil ing and said first panel or glazing system exposed externally of the building, wherein said second inlet vent is open, said first outlet vent is open and said other vents are closed to warm the building with air frcm outside the building, said second inlet and outlet vents are closed and said first inlet and outlet vents are open to warm the building with air circulated frcm inside, or both of said inlet vents are open, said first outlet vent is open and said second outlet is closed.

According to a seventh aspect of the invention a method of cooling or preventing solar heating of a building having apparatus in accordance with said fifth aspect has said first pane exposed internally of the building and said first panel or glazing system exposed externally of the building, wherein said first inlet vent is open, said second outlet vent is open and said other vents are closed to vent air frcm the building, said first inlet and outlet vents are closed and said second inlet and outlet vents are open to cool the apparatus with air circulated from outside the building, or both of said inlet vents are open, said first outlet vent is closed and said second outlet is open.

According to an eighth aspect of the invention a vented windcw apparatus comprises a frame housing in spaced apart relationship a first pane of generally transparent glass or plastics and a first glazing system in accordance with said first or second aspect or a first solar panel in accordance with said third or fourth aspect to define an air-space therebetween, having disposed above either said first pane or said first system/panel a closable outlet vent and below either said first pane or said first system/panel a closable inlet vent, with the arrangement providing that solar energy absorbed by said first pane, system or panel can be removed by convection of air through the air-space when the two vents are open.

According to a ninth aspect of the invention a vented window apparatus comprises a frame housing in spaced apart relationship a first pane of generally transparent glass or plastics and a first glazing system in accordance with said first or second aspect or a first solar panel in accordance with said third or fourth aspect to define an air-space therebetween, having disposed above either said first pane or said first systempanel an outlet vent and below either said first pane or said first system/panel an inlet vent, with the arrangement providing that solar energy absorbed by said first pane, system or panel can be removed by convection of air through the air-space.

Preferably, the frame houses a second pane of generally transparent glass or plastics, a second glazing system in accordance with said first or second aspect or a first solar panel in accordance with said third or fourth aspects to define a second air-space therebetween, having disposed above said second pane, panel or system a third outlet vent and below said second pane, panel or system a third inlet vent. Both of said third inlet and outlet vents may be closable.

Said first pane may be replaced by either a further glazing system in accordance said first or second aspect or a further solar panel in accordance with said third or fourth aspect.

-anbodiments of the invention will now be more particularly described by way of exaπple only and with reference to the acccπpaπying drawings, in which:-

Figure 1 is a graphical representation of 'black body' radiation of the sun and the photopic response function of a human eye; Figure 2 is a graphical representation of the photopic response function also shown in Figure 1, the transmission response of typical float glass, and the relative solar response of an embodiment of the invention;

Figure 3 is a vented windcw apparatus in accordance with a first embodimsnt according to one aspect of the invention;

Figure 4 is a vented window apparatus in accordance with a second embodiment of the invention with similar parts to those of said first embcdiment shown in Figure 3 being denoted by like numbers;

Figure 5 is a vented window apparatus in accordance with a third embodiment of the invention similar to the embodiment shown in Figure 3 with like parts being denoted by like numbers, and

Figure 6 is a vented window apparatus in accordance with another aspect of the invention.

The optical transmission characteristics of most transparent or translucent glazing materials can be defined by reference to their visible light transmission (LT) , energy absorption (EA) and solar shading coefficient (SC) . Desirably a glazing system should have high LT, high EA and low SC which would permit transmission of high natural daylight and low transmission of solar energy. However, solid materials having high EA usually mean that the glazing also acts as a radiator thus effectively increasing SC. Because of their broad spectral characteristics, most window/cladding elements of glazing systems cannot • exhibit the aforedescribed desirable cαnbination of high LT, high EA and low SC.

Typical values for reflective glass are:- LT 10%, EA 60%, SC 0.26 Typical values for tinted glass are:- LT 72%, EA 49%, SC 0.72 Typical values for clear float glass are:- LT 87%, EA 15%, SC 0.95

Hitherto, glass manufacturers have assumed that high LT, high EA and low SC in the same material is physically iipossible. The inventor considers this assumption to be based on the false premise that the human photopic response curve in the visible spectrum has the same profile as the solar transmission curve within that spectrum. As can be seen frcm Figure 1 that is not the case. Graph 1 is the internationally agreed photopic function CIE 18(E-1.2)1970 and graph 2 represents black body solar radiation.

In Figure 1 the chain lines at 'a' and 'd' illustrate the half power band width 510 to 610 milli-miσrons wavelength on curve 1, i.e. of the human eye. chain lines at 'A' and 'B' indicate the full response of the typical human eye i.e. between 360 and 830 millimicrons.

Although the response of the human eye extends between 360 to 830 millimicrons the major part of its sensitivity is in the aforementioned 'half power band' width of electrcmagnetic theory with a maximum at 555 millimicrons. At sea level the solar spectrum extends from 200 to 30,000 milli icrons with most of the energy within the range 240 to 2000 millimicrons. It will be appreciated that daylight within the 'half band pcwer width' between 'a' and 'b' is of particular value to human sight and the remaining wavelengths can be considered redundant for that purpose and provide unwanted solar energy in sunnier and valuable heating in winter.

A material or combination of materials having negligible reflection that matched the sensitivity function of the eye (particularly in the wavelength range 510 to 610 milli-microns) would have desirable optical characteristics having approximate values of LT in the visual spectrum of 89%, EA of 89% ad SC of 0.11. Such would appear glass clear but almost totally absorbing of the aforementioned redundant wavelengths of solar energy. Self-evidently with such a high degree of absorption the material or combination would tend to get 'hot' and radiate absorbed energy in the infrared band-width thus effectively degrading the SC. In one embodiment of the invention described hereinafter a ccmbination of materials is suggested having the aforementioned desirable characteristics. Whilst in the embodiments illustrated in Figures 3 to 5 'cooling' means described hereinafter are provided which will maintain a generally lew temperature for said material or combination thus obviating the otherwise degradi g effect on the SC thereof. By appreciating that it is the cc bined transmission response of glass, coating and/or doping materials which is of importance, the inventor has suggested in one em-xxiiment of his invention that a pane of float glass (not shown) be coated with a dye such as pthalocyanine at a suitable concentration to provide a solar response curve similar to that shown as curve 3 in Figure 2. In that Figure the curve 1 corresponds to the photopic response curve in Figure 1 and curve 4 is the transmission response curve of typical float glass.

In another embodiment a glazing unit (not shown) is in the form of two parallel panes of float glass separated by at least one channel carrying an energy absorbent cooling fluid. Preferably, the panes are 6mm thick separated by a 6πm fluid filled gap. The fluid is a water solution of pthalocyanine dye having a concentration of 40 ppm giving the response curve 3. This provides for combined characteristics LT in the human visual spectrum of approximately 60%, EA of about 74% and SC 0.07. A concentration of 200 ppm would give the undesirable characteristics of LT 16%, EA 94% and SC 0.07. It will be appreciated that the liquid used could be caused to circulate externally of the glazing unit to be dissipated elsewhere in suπmer and for heating purposes in winter, for exairple.

By appropriate choice of glazing materials, coating/doping agents and/or coolant coπposition, and physical dimensions and configuration it is possible to achieve characteristics better approximating curve 1. The choice of coolant and/or coating/doping agent can be made by appropriate mathematical analysis of the transmission characteristics of the energy source (the sun at the desired latitude), the ambient atmosphere, the glass ccπposition and the human eye. It will be appreciated that dyestuffs may be added to achieve any desired colouring effects.

The aforedescribed embodiπents provide for glazing systems which improve on existing solar energy systems using darkened glass and/or coolant fluids to achieve high EA. They also enable natural daylighting of buildings without enormous air-conditioning costs which makes them particularly useful in multi-storey structures. If embodiments using coolant are employed heat from the coolant may be extracted by suitable heat exchangers or heat-pumps. If these are placed in a -suitable area of the building, such as the well of a staircase, which will act as a flue then the upward movement of air can be used to ventilate floors of the building. In large buildings such air movement could be used to drive air-turbine generators during the night, for example

In the embodiment illustrated in Figure 3 a vented window apparatus 10 comprises a framework having an upper beam 11 and lower beam 12 and a pair of sheets of float glass panes 13,14 held in parallel spaced apart relationship to define an air-space 15 therebetween. The first pane 13, adapted to be disposed inwardly of a building to which the frame 1 is fitted, is a sheet of plain float glass which may have its outwardly disposed surface 16 coated with a low emissivity or long wavelength reflective agent. Said other pane 14 is typically in accordance with the aforesaid one embodiment of the invention wherein its inwardly disposed surface 17 or outwardly disposed sur ace 18 is coated with a suitable agent or agents. Both surfaces 17,18 could be coated. Alternatively, the glass of pane 14 could be doped and may also be coated with a suitable agent or agents. Consequently, it is the said other pane 14 which is mostly responsible for the solar energy absorption of the apparatus 10.

The apparatus 10 also comprises a plurality of vents. Disposed above and belc-w the first pane 13 are respectively closable outlet vent 19 and inlet vent 20 which can permit the interior/inside of the building to c ππunicate with the air-space 15. Similarly to permit ccmmunication with the exterior/outside of the building outlet vent 21 and inlet vent 22 are disposed respectively above and belcw said other pane 14.

Energy absorbed by said other pane 14 will heat air within the air-space 15. Controlled operation of vents 19 to 21 will allow convection to force movement of air between inlet and outlet vents that are open. Consequently, by appropriate operation of the vents, it is possible to vent that air externally or internally of the buil ing using air fran either the interior, exterior or both interior and exterior of the building. Alternatively, by closing all vents the glazing apparatus 10 performs as conventional double glazing. Different permutations of vent closure and opening permit variously heating, cooling and/or ventilation of the interior.

The first pane 13 will tend to remain at a low teπperature approximating the ambient interior room teπperature. This pane 13 could be coated with a thermotropic or themochromic material that would automatically reduce the light transmission as it heated thereby further reducing the transmission of solar energy. Also, so long as the pane 13 remains 'cool' electro-optical and photo-chrαnic devices that automatically vary visible light transmission can be attached to the surfaces thereof. Advantageously, the pane 13 remaining 'cool' avoids the incidence of thermal problems often associated with the aforesaid devices.

It will be appreciated that energy absorbed by said other pane 14 will also be lost to the exterior/outside of the building. In colder climates, or those having hot summers and extremely cold winters, this may not be desirable. The vented window apparatus 30 illustrated in Figure 4 overcαnes this disadvantage by providing in addition to panes 13,14 an outer pane of float glass 31 to provide a further air-space 32. The pane 31 is provided with inlet and outlet vents 33,34 respectively for use in venting the interior and for cooling of the interior during sunnier months. In winter months the vents 33,34 when closed permit the air-space 32 to be vented internally of the building. Alternatively, vents 21,22,33 and 34 can be closed so that panes 18 and 31 provide conventional double glazing. It will be understood that the double glazing will result in the teπperature within air-space 32 rising above the aπibient external temperature thereby reducing heat loss from pane 18 into that air-space.

The operation and function of the embodiment shown in Figure 5 is essentially the same as that of Figure 3. However, instead of a coated exterior pane (pane 14 in Figure 3) this embodiment is provided with a solar panel 40 comprising an inner pane of float glass 41 disposed in spaced apart relationship to an outer pane of float glass 42 to define a coolant channel 43 therebetween. The solar panel 40 is in the form of the aforedescribed said another embodiment. Figure 6 illustrates a vented window or wall apparatus 50 in accordance with another aspect of the invention which is not claimed in this Application but which may be claimed in a Divisional filing at a future date. The apparatus 50 comprises a frame housing in spaced apart relationship clear glass panes 51, 52 and optionally a third pane 53 which define an air-space 54 or air-spaces 54,55 vented as those in aforedescribed eπibc-diments. In this embodiment pane 51 could be replaced by an opaque and/or thermally insulated sheet and pane 52 could be replaced by thermal unit such as that denoted 40 in Figure 5 or a coated/doped pane as aforedescribed. The apparatus could be used for forced venting of the interior or for heating the interior where illumination was not desired.

It will be appreciated that the aforedescribed venting need not have the illustrated configuration(s) . For example, vents could be provided within the associated framework. Alternatively, the framework could be provided with inlet and outlet ports leading to controllable valve means. Also, if the internal pressure of the building is varied relative to atmospheric pressure then many more modes of heating, cooling and 'natural' ventilation could be achieved. Also, it is possible that by provision of suitable ducting air could be blown into the appropriate air-space(s) and if desired thereafter irected to any part of the building or to atmosphere.

Where solar panels such as that denoted 40 in Figure 5 are used, the coolant/heat absorbing liquid may be puπped via heat exchangers or heat-pumps to remote parts of the building, e.g. frcm a sunny to a shaded side of the building.

Claims

CLAIMS:

1. A glazing system comprising a pane of transparent or translucent material and a doping agent and/or coating agent the ccmbined optical characteristics of the system providing solar energy transmission therethrough having a transmission curve closely approximating the photopic response function CIE 18(E-1.2)1970.

2. A glazing system ccmprising a pane of generally transparent or translucent material and a doping agent and/or coating agent applied to one surface of the pane the combined optical characteristics of which permit light transmission through the system of the majority of wavelengths of solar energy visible to a human eye and which provide for absorption by the glass and the coating of the majority of solar energy invisible to the human eye.

3. A glazing system in accordance with claim 1 or claim 2, wherein the doping agent and/or coating agent is pthylocyanine.

4. A glazing system in accordance with claim 3 wherein the doping agent and/or coating agent has a concentration in a range equivalent to between 40 and preferably approximately 80 ppm in aqueus solution.

5. A solar energy collecting panel comprising two panes of glass or generally transparent plastics and at least one fluid passageway therebetween with a solution of dyestuff cont ined within the passageway, with the arrangement providing that the ccmbined optical characteristics of the panel provide solar energy transmission therethrough having a transmission curve closely approximating the photopic response function CIE 18(E-1.2)1970.

6. A solar energy collecting panel ccmprising two panes of glass or generally transparent plastics and at least one fluid passageway therebetween with a solution of dyestuff contained within the passageway, with the arrangement providing that the ccmbined optical characteristics of the panel permit light transmission through the panel of the majority if not all wavelengths of solar energy visible to a human eye and which provide for absorption by the glass and the coating of the majority of solar energy invisible to the human eye.

7. A solar panel in accordance with claim 5 or claim 6, wherein the dyestuff is water soluble pthylocyanine.

8. A solar panel in accordance with claim 7 wherein the pthylocyanine has a concentration in the range of 30 to 200 ppm.

9. A solar panel in accordance with claim 7 wherein the pthylocyanine has a concentration in the range of 60 to 80 ppm.

10. A solar panel in accordance with claim 7 wherein the pthylocyanine has a concentration in the order of 40 ppm.

11. A vented window apparatus cc-πprising a frame housing in spaced apart relationship a first pane of generally transparent glass or plastics and a first glazing system in accordance with any one of claims 1 to 4 or a first solar panel in accordance with any one of claims 5 to 10 to define an air-space therebetween, having disposed above said first pane a first closable outlet vent, below said first pane a first closable inlet vent, above said first system or panel a second closable outlet vent and belcw said first system or panel a second closable inlet vent, with the arrangement providing that solar energy absorbed by said first pane, system or panel can be removed by convection of air through the air-space when one, other or both of said first inlet vents is or are open and one, other or both of said first outlet vents is or are open.

12. A method of heating a building having apparatus in accordance with claim 11 with said first pane exposed internally of the building and said first panel or glazing system exposed externally of the building, wherein said second inlet vent is open, said first outlet vent is open and said other vents are closed to warm the building with air frcm outside the building, said second inlet and outlet vents are closed and said first inlet and outlet vents are open to warm the building with air circulated from inside, or both of said inlet vents are open, said first outlet vent is open and said second outlet is closed.

13. A method of cooling or preventing solar heating of a building having apparatus in accordance with claim 11 having said first pane exposed internally of the building and said first panel or glazing system exposed externally of the building, wherein said first inlet vent is open, said second outlet vent is open and said other vents are closed to vent air from the building, said first inlet and outlet vents are closed and said second inlet and outlet vents are open to cool the apparatus with air circulated from outside the building, or both of said inlet vents are open, said first outlet vent is closed and said second outlet is open.

14. A vented window apparatus comprising a frame housing in spaced apart relationship a first pane of generally transparent glass or plastics and a first glazing system in accordance with any one of claims 1 to 4 or a first solar panel in accordance with any one of claims 5 to 10 to define an air-space therebetween, having disposed above either said first pane or said first system/panel a closable outlet vent and below either said first pane or said first system/panel a closable inlet vent, with the arrangement providing that solar energy absorbed by said first pane, system or panel can be removed by convection of air through the air-space when the two vents are open.

15. A vented window apparatus comprising a fraπe housing in spaced apart relationship a first pane of generally transparent glass or plastics and a first glazing system in accordance with any one of claims 1 to 4 or a first solar panel in accordance with any one of claims 5 to 10 to define an air-space therebetween, having disposed above either said first pane or said first system/panel .an outlet vent and below either said first pane or said first system/panel an inlet vent, with the arrangement providing that solar energy absorbed by said first pane, system or panel can be removed by convection of air through the air-space.

16. Apparatus in accordance with claim 11, claim 14 or claim 15, wherein the frame houses a second pane of generally transparent glass or plastics, a second glazing system in accordance with any one of claims 1 to 4 or a first solar panel in -accordance with any one of claims 5 to 10 to define a second air-space therebetween, having disposed above said second pane, panel or system a third outlet vent and below said second pane, panel or system a third inlet vent.

17. Apparatus in accordance with claim 16, wherein either or both of said third inlet and outlet vents are closable.

18. Apparatus in accordance with claim 11 or any one of claims 13 to 17, wherein said first pane is replaced by either a -further glazing system in accordance with any one of claims 1 to 4 or a further solar panel in accordance with any one of claims 5 to 10.