AU3735989A

AU3735989A - Controlling solar energy transmittance of a glazing panel

Info

Publication number: AU3735989A
Application number: AU37359/89A
Authority: AU
Inventors: Lionel James Barden; James Gregor Loftus-Hills
Original assignee: Australian Tectonic Dev Pty Ltd
Current assignee: AUSTRALIAN TECTONIC DEVELOPMENT PTY Ltd
Priority date: 1988-05-04
Filing date: 1989-05-04
Publication date: 1989-11-29
Anticipated expiration: 2009-05-04
Also published as: AU627744B2

Description

CONTROLLING SOLAR ENERGY TRANSMITTANCE OF A GLAZING PANEL

Field of the Invention This invention relates to controlling solar energy transmittance of a glazing panel and relates particularly, but not exclusively, to such in connection with overhead glazing such as over a roof area of a building. Description of Prior Art In recent times it has been common to glaze overhead areas in buildings. Typically, modern buildings have favoured a central atrium and it has been found extremely difficult to control the solar energy transmitted through the glazing panel so that designers of air conditioning apparatus can accurately predetermine a maximum heat load for the building in such circumstances. In other instances, garden windows have become quite popular and it has been found extremely difficult to control or have a predetermined maximum amount of solar energy transmitted through the overhead portion of the garden window.

A further problem with overhead glazing is that at night time, the glazing appears to represent a black sky area in the building. This is particularly so in connection with atriums .

A further problem with overhead glazing is that it has been exceedingly difficult for lighting engineers to provide for illumination in the atrium area without resorting to suspended down-lights or alternatively flood lights which apply light directly to the floor area under such glazing.

Objects and Statement of Invention We have discovered that solar energy transmittance can be controlled to a predetermined maximum amount by the application of a patch or pattern as a screen in association with the glazing. The patch or pattern itself can be controlled so that a maximum predetermined amount of solar energy can be transmitted therethrough. Where the suitable patch or pattern is applied as a screen, it is possible for lighting engineers to, in turn, direct light upwardly onto the glazed area and provide illumination of the patch or pattern in the screen which will, in turn, cause light to be reflected downwardly and provide for an enhanced illumination under the overhead glazing. The black sky effect no longer exists.

Therefore, according to a first broad aspect of the present invention there may be provided a method of providing predetermined solar energy transmittance to an area of a glazing panel comprising:

(a) determining a desired solar energy transmittance; (b) calculating the ratio of a covering of said area required to provide said desired solar transmittance;

(c) applying covering to said glazing panel in said ratio. In accordance with a further broad aspect of the present invention there may be provided a method of providing predetermined solar energy transmittance to a glazing panel comprising:

(a) selecting a glazing panel material; (b) determining a patch or pattern to be used as a screen which will provide, with said glazing panel, solar transmittance approximately equal to said predetermined solar energy transmittance; (c) applying the screen as a medium over said glazing panel; and

(d) obtaining said predetermined solar energy transmittance by appropriately choosing the solar energy transmittance properties of said medium itself.

According to a further broad aspect of the present invention there may be provided a method of providing predetermined solar energy transmittance properties to a glazing panel comprising: (a) selecting a glazing panel material; (b) determining the solar energy transmittance factor of said glazing panel material;

(c) determining a patch or pattern to be applied as a solar energy screen with said glazing panel;

(d) selecting a medium to constitute the screen; and

(e) applying said medium to form said screen with said glazing panel whereby the following relationship applies:-

^x = ^(Lι ^x !_> ^{+ (L}2 ^x -V

T T where X = predetermined solar energy transmittance property of the finished glazing panel as a percentage;

Ir-, = solar energy transmittance factor of the patch or pattern of the medium in said screen;

L„ = solar energy transmittance factor of said glazing panel without said screen;

P = patch or pattern area expressed in ²;

C = area of glazing panel not covered by

2 said screen expressed m m ; and

T — total surface area of said glazing panel expressed in m .

In accordance with a further aspect of the present invention there is provided a glazing panel produced by any one of the aforementioned inventive methods.

According to a further broad aspect of the present invention there may be provided a glazing panel which has a predetermined solar energy transmittance property wherein said panel comprises a first glazing membrane and a second glazing membrane extending co-planar with said first glazing membrane and a medium between said first glazing membrane and said second glazing membrane which will provide a covering or a patch or pattern as a screen between the first and second membranes.

Most preferably the medium is a printing ink. Most preferably the peripheral edges of the glazing panel have a peripheral rib thereon. The peripheral rib is such that when an adjacent similar glazing panel is abutted, the ribs on each will be adjacent so that a connecting member can be placed over said peripheral ribs to hold said glazing panels in assembled side by side relationship. Most preferably the peripheral rib is formed with a snap-lock engaging means and a connector which is used to hold the glazing panels in assembled relationship, has co-operating snap-lock engaging means, whereby the glazing panels can be snap-locked together.

Brief Description of Drawings

In order that the invention can be more clearly ascertained, examples of preferred embodiments will now be described with reference to the accompanying drawings, wherein: Figure 1 is a diagrammatic view of a building with an overhead glazed area;

Figure 2 shows one example of a typical pattern used to form a covering or screen for use with the glazing panels; Figure 3 shows an alternative pattern;

Figure 4 shows an even further alternative pattern;

Figure 5 shows a side cross-sectional view of a preferred glazing panel; and Figure 6 shows a close-up side cross-sectional view of two such glazing panels and the method of interconnection.

Detailed Description of Preferred Embodiments Referring firstly to Figure 1 there is shown a typical example of a building which has overhead glazing 1 incorporating a screen 3 or covering. The screen 3 is of a predetermined area whereby a predetermined amount of solar energy will be transmitted through the glazing 1. The pattern of the screen 3 can be any desired pattern and typical examples are shown in Figures 2, 3 and 4. Other examples may be company logos or pleasing pictures. The requirement is that the screen 3 provide a predetermined amount of solar energy transmittance with the glazing 1.

Typical materials from which the glazing 1 can be made are glass - clear or tinted, polycarbonate - clear or tinted, single or multiple skin, acrylic materials - clear or tinted, single or multiple skin, or other suitable roofing materials.

In order to predetermine the solar transmittance it is necessary to first calculate the transmission factor of the glazing material. The second step is to determine a required decorative patch or pattern for the screen or covering 3. A third step is to select an ink or paint type to be used on the particular glazing material. A colour is chosen to suit aesthetic requirements. By the addition of white or black pigments or silver or aluminium flake to the original colour, a varied percentage of blockout can be achieved. The ink or paint is silk-screened onto the glazing material for accuracy and consistency of the screen. The light transmission factor of the ink or paint can be determined by tests on various samples. Calculation for the solar energy transmission of the finished material is predicted in accordance with the following formula:

X = (L. x ^) + (L₂ x £)

T T where X - predetermined solar energy transmittance property of the finished glazing panel as a percentage;

L, = solar energy transmittance factor of the patch or pattern of the medium in said screen;

L- = solar energy transmittance factor of the glazing panel without the screen;

2

P = patch or pattern area expressed in m ;

C = area of glazing panel not covered by the

2 screen expressed in m ; and

T = total surface area of the glazing panel

2 expressed in m .

By knowing the amount of solar energy transmitted through the glazing 1 it is possible to predict the amount of heat which can be transmitted from the sun into a building and hence it is possible for engineers designing air-conditioning for a building to know a maximum possible heat load and design the air-conditioning system accordingly. Because the screen 3 is provided on the glazing

1, it is then possible for lighting engineers to direct light upwardly onto the glazing 1 so that the screen will be illuminated at night and will reflect light downwardly therefrom to illuminate the area underneath the glazing 1. A lighting engineer can, by knowing the reflective area relative to the total area of the glazing 1, be able to predict the amount of light which is required to provide for safe illumination under the glazing 1.

Referring now to Figures 5 and 6 there is shown one typical glazing panel 5. The glazing panel 5 is typically of a width of about 600 mm. Other widths can be provided if required. The length is determined by having regard to the length in which the glazing material is manufactured and also having regard to the physical requirement of an installer carrying the glazing panel 5. The glazing panel 5 can typically be manufactured from acrylic sheet. It has a first glazing membrane 7 and a second glazing membrane 9. The first and second glazing membranes 7 and 9 are co-planar and have a screen 11 therebetween. The screen 11 may be printed and/or painted thereon with suitable inks and/or other coatings. The arrangement is such that the screen 11 is sandwiched between the first and second glazing membranes 7 and 9 and thus protected from the effects of weather and from being removed by accidental contact with objects which may contact either the first or second glazing membranes 7 and 9. Each glazing panel has a peripheral rib 31 in the form of a shallow lip formed from each of the first and second glazing membranes 7 and 9. Typically the screen 11 will not extend into the region of the peripheral rib 13. It can be seen in Figure 6 that the peripheral rib 13 is provided with a serrated cross-sectional surface on at least the first glazing membrane 7. This permits use of a snap-on connector 15 which has corresponding serrations therein to permit adjacent glazing panels to be held in assembled relationship.

If desired, the first glazing membrane 7 may be of an acrylic material whilst the second glazing membrane 9 may be of a polycarbonate material. Such combination of materials will yield high UV protection whilst considerably strength to the glazing panel. The first glazing membrane 7 and the second glazing membrane 9 may be held to each other by suitable adhesive mediums.

Modifications may be made to the invention as would be apparent to persons skilled in the glazing arts and/or coating arts. For example, the first and second glazing membranes 7 and 9 may not be integrally attached to each other as a physical glazing panel but can be assembled relative to each other and held in that relationship by use of a snap-on connector 15. Instead of coating the screen in the form of printing it may be applied as a web of other material. For example, it may be possible to punch material which has a known solar block-out property and apply the punched material to the glazing to give the required solar energy transmittance characteristic to the glazing panel.

In addition, existing glazing may be treated with a screen calculated in accordance with the above concepts to give a predetermined solar energy transmittance property to the glazing. These and other modifications may be made without departing from the ambit of the invention, the nature of which is to be determined from foregoing description.

Claims

1. A method of providing predetermined solar energy transmittance to an area of a glazing panel comprising:

(a) determining a desired solar energy transmittance;

(b) calculating the ratio of a covering of said area required to provide said desired solar transmittance;

(c) applying covering to said glazing panel in said ratio.

2. A method of providing predetermined solar energy transmittance to a glazing panel comprising:

(a) selecting a glazing panel material;

(b) determining a patch or pattern to be used as a screen which will provide, with said glazing panel, solar transmittance approximately equal to said predetermined solar energy transmittance;

(c) applying the screen as a medium over said glazing panel; and

3. A method of providing predetermined solar energy transmittance properties to a glazing panel comprising:

(a) selecting a glazing panel material;

(b) determining the solar energy transmittance factor of said glazing panel material;

(c) determining a patch or pattern to be applied as a solar energy screen with said glazing panel; (d) selecting a medium to constitute the screen; and

X = (L_χ x ) + (L₂ x £)

L₂ = solar energy transmittance factor of said glazing panel without said screen;

P = patch or pattern area expressed in mm²;-

C = area of glazing panel not covered by said screen expressed in m 2; and

T = total surface area of said glazing panel ₁ expresse_d. i•n 2.

4. A glazing panel with a predetermined solar energy transmittance property produced by the method of Claim 1.

5. A glazing panel with a predetermined solar energy transmittance property produced by the method of Claim 2.

6. A glazing panel with a predetermined solar energy transmittance property produced by the method of Claim 3.

7. A glazing panel which has a predetermined solar energy transmittance property wherein said panel comprises a first glazing membrane and a second glazing membrane extending co-planar with said first glazing membrane and a medium between said first glazing membrane and said second glazing membrane which will provide a covering or a patch or pattern as a screen between the first and second membranes.

8. A glazing panel as claimed in Claim 7 wherein said medium is a printing ink.

9. A glazing panel as claimed in Claim 7 wherein the peripheral edges have a peripheral rib so that when two such panels are brought into side-by-side relationship and abutted so that the two panels can be held together by a connecting member.

10. A glazing panel as claimed in Claim 9 including snap-lock engaging means formed in said peripheral rib for permitting a corresponding co-operating connecting member to snap-lock therewith to hold two glazing panels together.