Title:
ENERGY EFFICIENT INSULATED GLASS UNIT
Kind Code:
A1


Abstract:
An insulated glass unit (IGU) comprises impact resistant safety films on the inner surfaces of the glass panes, providing an impact resistant, energy-saving IGU for use in windows and doors. A layer of the safety film providing energy savings may be trimmed from the edges of a glass pane; witch may be sealed within the interior of the IGU, preventing corrosion while providing no loss in impact resistance. A scratch-resistant, chemical vapor deposited coating may be added to an interior glass surface (i.e. facing the building interior) in order to prevent heat loss from the building. An IGU may have an Energy Star rating for both summer and winter use.



Inventors:
Huang, Haibin (Tampa, FL, US)
Duncan, Craig (Hudson, FL, US)
Abate, Kenneth (Beaver Falls, PA, US)
Application Number:
11/773278
Publication Date:
05/22/2008
Filing Date:
07/03/2007
Primary Class:
International Classes:
E06B3/663
View Patent Images:
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Primary Examiner:
LONEY, DONALD J
Attorney, Agent or Firm:
Paradies Law P.A. (Seffner, FL, US)
Claims:
What is claimed:

1. An insulated glass unit comprising: a first glass pane having a first surface and a second surface opposite of the first surface; a second glass pane having a third surface and a fourth surface opposite of the third surface; a first safety film comprised of a plurality of polymer films adhesively laminated one to the other is adhesively bonded to the second surface of the first glass pane; a second safety film comprised of a plurality of polymer films adhesively laminated one to the other and a metallized coating on one surface of the plurality of polymer films is adhesively bonded to the third surface of the second glass pane such that the metallized coating is opposite of the adhesively bonded surface of the second safety film; a spacer positioned between the first safety film on the second surface and the second safety film on the third surface of the second glass pane, such that the spacer separates the first glass pane from the second glass pane; a frame enclosing the perimeter of the first glass pane and the second glass pane such that a space is defined between the spacer and the frame; and a sealant backfilled within the space defined by the spacer and the frame such that the insulated glass unit is sealed from moisture or damp air.

2. The insulated glass unit of claim 1, wherein the plurality of polymer films of the first safety film and the second safety film are of polyethylene terephthalate.

3. The insulated glass unit of claim 2, further comprising an inert gas within a cavity defined by the first glass pane, the second glass pane, and the spacer.

4. The insulated glass unit of claim 1, wherein the first safety film and the second safety film have a thickness ranging from 0.004 to 0.0025 inches.

5. The insulated glass unit of claim 1, wherein the metallized coating is a pyrolytically applied layer.

6. The insulated glass unit of claim 1, wherein the metallized coating has an emissivity in a range of 0.03-0.30.

7. The insulated glass unit of claim 6, wherein the metallized coating has a visible light transmission in a range of 35-91%.

8. The insulated glass unit of claim 1, wherein a perimeter portion of the metallized coating is removed before the insulated glass unit is sealed.

9. The insulated glass unit of claim 1, further comprising a low emissivity coating on the fourth surface of the second glass pane.

10. The insulated glass unit of claim 9, wherein the low emissivity coating is scratch resistant.

11. The insulated glass unit of claim 1, further comprising a metallized layer on a surface of the first safety film opposite of the surface adhesively bonded to the first glass pane.

12. The insulated glass unit of claim 11, wherein a perimeter portion of the metallized layer is trimmed before the insulated glass unit is sealed.

13. The insulated glass unit of claim 1, wherein an ultraviolet absorbing material is added to the adhesive used to adhesively bond one or more of the first safety film to the first glass pane on the second safety film to the second glass pane or one of the plurality of polymer films of the first safety film or the second safety film to one of the other of the plurality of polymer films.

14. An insulated glass unit comprising: a first glass pane having a first surface and a second surface opposite of the first surface; a sputtered solar control low emissivity coating on the second surface of the first glass pane; a second glass pane having a third surface and a fourth surface opposite of the third surface; a first safety film comprised of a plurality of polymer films adhesively laminated one to the other is adhesively bonded to the second surface of the first glass pane; a second safety film comprised of a plurality of polymer films adhesively laminated one to the other is adhesively bonded to the third surface of the second glass pane; a spacer positioned between the first safety film on the second surface and the second safety film on the third surface of the second glass pane, such that the spacer separates the first glass pane from the second glass pane; a frame enclosing the perimeter of the first glass pane and the second glass pane such that a space is defined between the spacer and the frame; and a sealant backfilled within the space defined by the spacer and the frame such that the insulated glass unit is sealed from moisture or damp air.

15. The insulated glass unit of claim 14, wherein an adhesive comprises an ultraviolet blocking agent and the adhesive is used in one or more of the adhesive laminating of one or more of the plurality of polymer films or adhesive bonding of the first safety film to the first glass pane or the second safety film to the second glass pane.

16. The insulated glass unit of claim 14, wherein the sputtered solar control low emissivity coating is scratch resistant.

17. The insulated glass unit of claim 14, wherein the sputtered solar control low emissivity coating has an emissivity in a range of 0.03-0.30.

18. The insulated glass unit of claim 14, wherein the sputtered solar control low emissivity coating has a visible light transmission in a range of 35-91%.

19. The insulated glass unit of claim 14, wherein the plurality of polymer films of the first safety film and the second safety film are of polyethylene terephthalate.

20. The insulated glass unit of claim 14, wherein the first safety film and the second safety film have a thickness ranging from 0.004 to 0.0025 inches.

Description:

RELATED APPLICATION

This present application is a continuation of application Ser. No. 10/975,512, filed Oct. 28, 2004, now Allowed and application Ser. No. 10/793,958, filed Mar. 5, 2004, now Allowed.

FIELD OF THE INVENTION

The field relates to insulated glass units (IGUs) having a plurality of glass panes for use in energy efficient windows.

BACKGROUND

Insulated glass windows or door units have been known for many years to reduce the heat transfer between the interior house and the environment. To further improve the insulating properties, the art taught making solar control coated and low emissivity (low-E) coated glass or film. Solar control is a term describing the property of regulating the amount of solar heat energy, which is allowed to pass through a glass article into an enclosed space such as a building or an automobile interior. Low emissivity is a term describing the property of an article's surface wherein the absorption and emission of mid-range infrared radiation suppressed, making the surface a mid-range infrared reflector and thereby reducing heat flux through the article by attenuating the radiant component of heat transfer to and from the low emissivity surface. By suppressing solar heat gain, building and automobile interiors are kept cooler, allowing a reduction in air conditioning requirements and costs. Efficient low emissivity coatings may improve comfort during both summer and winter by increasing the thermal insulating performance of a window, but available glass systems usually have better energy efficiency in retaining heat or blocking sunlight and seldom both due well.

Two typical coating methods to make solar control and low-E coatings are “in-line” and “off-line” coatings. The in-line method uses a chemical deposition method involving doping with different chemicals to make an infrared absorbing layer and low-E layer as described in U.S. Pat. Nos. 5,750,265, 5,897,957 and 6,218,018. The off-line method uses sputtering deposition to make both coatings.

Impact resistant glass is described in detail in the Florida Building Code. Basically, it specifies a testing protocol for a window glass to withstand up to nine pounds of force from a 2×4 board shot at the glass up to 50 feet/second. Withstanding both shots with one in the center and one in the corner without penetration is considered as a pass.

U.S. Pat. Nos. 4,799,745 and 5,071,206 describe a multilayered polyethyleneterephthalate (PET) window film construction, which gives both solar control and low-E properties. The coating contains silver metal layers and indium-tin oxide layers in an alternate construction. The film has a high visible light transmission, above 70%, and a low visible light reflection, about 8%. The total solar heat rejection is about 56%. The color of the coating is light green. It has a very good solar control and low-E performances. However, corrosion is a major concern. To make an IGU, the window pane needs edge deletion and filling with inert gas in the IGU to prevent the coating from corroding. The multi-layered coating has to be exposed within the IGU to achieve both low-E and solar control functions. As a result, the manufacturing process for an IGU is expensive and difficult.

U.S. Pat. Nos. 5,332,888 and 6,558,800 disclose a multilayered sputtering window glass construction (off-line method) which also achieves both solar control and low-E properties. The description contains a silver metal layer sandwiched by zinc oxide layers or a silver metal layer sandwiched by nickel chrome and silica nitrite layers. Similar to sputtered PET film, they also face corrosion, chemical resistant and scratch resistant concerns, which make manufacturing difficult and expensive.

U.S. Pat. No. 6,546,692 assigned to Film Technologies International, Inc., discloses a method of laminating a safety film on the inside surfaces in an IGU to build an impact resistant window. The safety feature is very important for IGU's to withstand hurricane, earthquake, and terrorism. However, the low-E property is destroyed or significantly reduced once a safety film is laminated over any low-E coating surface.

Besides solar control, low-E, and impact resistance, other desirable properties include an economic and repeatable manufacturing process, durability, maintenance, light transmission, visibility, color, clarity and reflection.

To meet the Government (Department of Energy) Energy Star Qualification Criteria for Windows, Doors and Skylights and Florida Building Code for impact resistant windows, a new IGU is required for the window/door industry.

It is known that energy is controlled at a window by the reflection, transmission and absorption of solar radiation by the glazing type and emissivity of the glazing. An Insulated Glass Unit (IGU), which has a plurality of glass panes spaced apart and joined in a unit, contributes to the heat gain or loss of the window by three mechanisms: conduction of heat, convection whereby air currents within the IGU act as the transfer agent for heat, and radiation or reradiation of the heat absorbed. When solar radiation strikes an IGU energy is absorbed and either conducted or reradiated, The ability to reradiate is characterized by a surfaces emissivity

When a spectrally selective, vacuum deposited, metal or metallic coating is incorporated into the surface within an IGU, it assists with energy release by absorbing the IR portion of the solar spectrum and reradiating the absorbed energy to the surrounding atmosphere in the direction of the surface of the coating and the atmosphere interface. If the spectrally selective coating is encapsulated within a film system and the coating itself is not exposed to the environment, it has been discovered that the majority of the ability to reradiate energy is lost as conduction becomes the major pathway for the absorbed energy. Thus, it is important for a spectrally selective coating to be exposed to an atmosphere or void if surface emissivity is used for reradiation of the absorbed energy. Standard laminated glass where two pieces of glass are adhered together by a plastic and have no void or atmosphere separating the glass panes do not incorporate spectrally selective, vacuum deposited, metal or metallic coatings, because these coatings would not be effective in emitting absorbed energy back to the outside of the laminated window unit.

Also it is known that the reactivity of spectrally selective coatings consisting of multi-layers of vacuum deposited or sputter-deposited metals or metallic compounds can corrode depending on the chemical composition when exposed to moisture, light. or other chemicals. When this happens the corrosion products are aesthetically displeasing and the solar radiation controlling performance of the coatings is lost.

SUMMARY OF THE INVENTION

The ability to incorporate a spectrally selective, vacuum deposited, metal or metallic coating

within an IGU utilizing a film composite having an emitting coating on the inner surface or surfaces of the IGU provides enhanced absorbed heat dissipation capability as it takes advantage of the filtering out of IR light, absorbs most of the UV portion of the spectrum, allows for neutral colored visible light to be transmitted, and takes advantage of the emissivity of the coating to reradiate absorbed light. This provides for a better insulation value for the IGU portion of the window and enhanced safety performance because of the film laminate adhered to the inner surface of the glass.

Spectrally selective coatings are protected immediately after manufacturing a multi-layered film composite by providing temporary protective film which can be removed without harming the spectrally selective metallic film. This allows handling, shipping and processing without damaging the spectrally selective coating prior to completion of an IGU incorporating the film. The protective film is removed just before IGU manufacture which then incorporates these spectrally selective coatings within the cavity of an IGU. The cavity exposes the films, to a benign environment, substantially free of moisture. These measures ensure the integrity of the spectrally selective coating and the long term performance of the IGU as a superior insulator. Spectrally selective, vacuum deposited or sputter-deposited, metal or metallic coatings on a surface of a multi-ply plastic film composite in an IGU provides both impact resistance and energy efficiency without corroding the metallic coating.

For example, a glass substrates adapted for insertion into frame unit of an IGU by laminating film composite comprising a metallized coating on an outer layer of a thin, multi-film base to the glass pane, A protective film is temporarily applied over the metallized layer until the film is adhesively bonded to the glass pane, which is then sealed within the interior space of the IGU. The protective film is removed and an outer edge strip of the outer layer of the multi-film layer may be stripped away. The glass pane surfaces may be mounted in a frame with a metallized layer facing inwardly toward the opposite glass pane. A spacer keeps the glass panes apart and sealant is placed in the cavity formed by the space between the glass panes and the spacer to form a sealed IGU.

An advantage of the IGU is improved impact resistance combined with an energy efficiency that earns the Department of Energy Star Qualification criteria. Such an IGU may meet or exceed requirements of Florida and Miami Dade County for large missile impact, also. The process provides for a comparatively low cost and corrosion/discoloration free low energy window coating on an IGU.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings:

FIG. 1 is an exploded cross sectional view of a film composite of this invention containing a metallized layer.

FIG. 2 is an exploded cross sectional view of the film composite of FIG. 1 with a protective film over the metallized layer.

FIG. 3 is a cross sectional view of the film composite of FIG. 2 about to be bonded to a glass pane.

FIG. 4 is a cross sectional view of the outer film metallized layer edge stripped away.

FIG. 5 is a cross sectional view of two glass panes adapted for mounting in a frame with a spacer in between two film composite metallized layers.

FIG. 6 is a cross sectional view of two glass panes adapted for mounting in a frame with a spacer in between a film composite metallized layer and a non-metallized layer.

FIG. 7 is a cross sectional view of the two glass panes of FIG. 5 mounted in a frame.

FIG. 8 is a side elevational view of an insulated glass window of this invention mounted in a window frame.

FIG. 9 is a transmission spectrum of a glass pane on which is applied a solar control layer and a low-E layer on one surface.

FIG. 10 is a transmission spectrum of a glass pane on which is applied an alternate antimony based solar control and low-E coating.

FIG. 11 is a transmission spectrum of a glass pane on which is applied a low-E coating.

DETAILED DESCRIPTION

In the example of FIGS. 1 and 2, a film composite 10 is formed by laminating several layers of polyethyleneterephthalate (PET) films together. PET film layers 12 and 14 are held together by acrylic pressure sensitive adhesive 16 and PET film layer 18 is bonded to PET film layer 14 by acrylic pressure sensitive adhesive 20. PET layer 18 incorporates a spectrally selective vacuum deposited metallic coating 22 and protective coating is applied to the outer side of PET layer 18 to protect coating 22. In alternative examples, the method applies the metallized coating to the outer layer film 18 either before or after the outer layer of film 18 is adhesively bonded with an adjacent layer of multi-layered film composite film.

The individual plies of PET 14 and 16 do not have to be of the same thickness and are held together with the acrylic pressure sensitive adhesive 20. The different layers of PET film 12 and 14 can equal or vary significantly in thickness depending on desired properties, i.e., 2 mils laminated with mils, or 4 mils laminated to 4 mils, or 1 mil laminated to mils, etc. It is typical for the spectrally controlling PET film 18 to be based on a 1 to 3 mil PET film, but can be thicker. The resulting film composite 10 is classified as a safety film and is used to coat a window pane 26 as shown in FIGS. 3 and 4 by attachment with acrylic adhesive 28. This composite film thickness can vary from 4 mils to 30 mils total depending on the end use desired and the choice of individual PET film thickness. Other safety film can be used and the individual ply thickness can vary as can the number of plies used to manufacture the film composite. These films can be made of polycarbonate polyester or other like polymeric materials. It is important that during the manufacturing of the composite 10 that a protective, temporary, masking film is applied to protect the spectrally selective film 18 from the environment and contamination. The laminated film composite is laminated to one surface of the glass pane 26 with adhesive 28.

Just prior to manufacturing the IGU, the protective coating 24 is removed from the glass/laminated film composite surfaces as seen in FIG. 4. With care, and using the edge of the glass 26, a cut 32 through the outermost layer 18 of the film composite 10 parallel with the edge 30 of the glass 26 made on all sides of the glass/film composite laminate. Care is taken to only cut through the outer film 18 and to not disturb the other plies of PET film. The cut 32 is typically from 3/16″ to “from the edge 30 of the glass 26. The thin strip, bordered by the edge 30 of the glass, formed from the cut 32 is then removed leaving a picture frame appearance, FIG. 4, to the glass pane.

A glass pane/laminated film composite 10a shown in FIG. 6 can be similarly made using only PET films and not incorporating a spectrally controlled film. This too is classified as a safety film and is described in U.S. Pat. No. 6,546,692, incorporated herein by reference.

If desired, for aesthetics or performance, layers of colored film can be used with the film composites 10 and 10a. The color will influence the overall transmitted light but will not adversely influence the emissivity of the exposed spectrally selective coating.

Two of the laminated window panes shown in FIG. 5 are faced to each other with the spectrally selective coatings facing inward and a spacer 34 shown in FIGS. 5 and 6 having a top inboard surface 36 and a bottom outboard surface 38 is placed between the laminated surfaces of the two panes 26 and 40 and pressed together to form a multiple window pane composite or IGU shown in FIGS. 5 and 6. A structural silicone or butyl or like IGU glazing sealant 42 is backfilled from the outboard surface 38 of the spacer 34 to the edge 30 of the laminated window pane window as seated in a frame 44 as seen in FIG. 7. The IGU is preferably positioned on a setting block when installed in frame 44. The panes also can be used in a door system.

As an al ternate IGU composition, one can laminate to one of the panes 40 in the above IGU a glass/film composite 10a whereby there is no spectrally controlling layer in the film composite When this glass/film composite 10a is substituted in the pane 40 utilizing a spectrally controlling film layer 22 is not a needed. Then there is no need to remove a portion of the film composite as there is no spectrally selective coating to corrode. The film composite 10 or 10a can cover the total pane. The resulting IGU made with using one pane 26 with a spectrally controlling layer and one pane 40 without a spectrally controlling layer is shown in FIG. 6.

The spacer 34 employed should have a thickness sufficient so its outboard surface 38 extends about ¼″ to ⅝″ from the window pane edge 30 and its inboard surface is on the site line” of the window frame of the window in which it is placed. The width of the spacer 34 between the laminated window panes should be about ¼″ to 9/16″ but may be smaller or larger in order to allow for an overall thickness appropriate for the window in which it is being glazed.

Typically, a desiccant agent is incorporated with the spacer system in order to initially scavenge residual moisture within the IGU cavity and throughout the service life of the IGU.

Inert gas or mixtures may be used to replace the air within the IGU cavity and these techniques are well known within the industry. The inert gas or mixtures aid with the insulating performance of the IGU by mitigating the convection pathway for heat transfer, especially when incorporating a spectrally selective coating on the inside of the IGU cavity to emit absorbed energy.

The dimension by which the framing system overlaps the edge of the glazing infill or IGU should be between ˜ to 1 inch with ⅝″ to ⅞″ being preferred.

The minimum glass pane 26 or 40 thickness will vary depending on the area of use, wind load chart and building codes. About ⅜″ glass is suitable in most areas with a laminated film inner surface thickness of 0.0008 to 0.02 inch.

To meet solar control criteria, it would be ideal to coat a solar reflective coating on the exterior surface of a window pane. However, because of environmental aging, chemical reaction, corrosion or scratching caused by cleaning the window, the coating cannot be placed on the exterior surface.

Referring to FIG. 8, a solar control coating 112 is coated on the inside surface 102 of the first glass pane 114. The coating can be made either by sputtering deposition or chemical deposition method. A sputtered coating, as used in FIG. 9, has silver or other IR reflective metal layers sandwiched by metal oxide layers. This coating reflects more infrared rays than it absorbs. The metal composite provides the window glass with high visible light transmission and low visible light reflection as well as low-E properties. As a result, it is an ideal heat mirror product. The chemical vapor deposition coating has better chemical and scratch resistance than the sputtering coated product. It will absorb solar energy instead of reflect it. As a result, it builds a heat stress over the glass pane and could cause glass breakage. Another disadvantage is that it has a lower visible light transmission than sputtering coated glass to achieve the similar solar performance. The transmission spectra for the preferred solar control coatings are shown in FIG. 9 and FIG. 10. The most preferred solar control coating sold by Pittsburg Plate Glass Co. is shown in FIG. 9. A safety film 116 is laminated over the sputtered coating 112 on surface 102 to reinforce the glass and also protect the metal from corrosion and other chemical reactions during aging. However, once laminated with a safety film, it destroys or significantly reduces the low-E property.

A safety film 116 is constructed with three layers of clear PET film laminated to each other with a pressure sensitive adhesive. The safety film has a thickness of 0.004 to 0.025 inches. The preferred thickness is 0.008 to 0.018 inches and most preferred is a film thickness of 0.015 inches. The adhesive is an acrylic based pressure sensitive type. The coat weight of the mounting adhesive, which bonds the safety film to the glass, is between 12-17 Ib/ream. The multi-layered construction is better than a single layer PET film because it improves the film's impact resistance. More layers are better for impact resistance but the multi-layered laminating construction can cause distortion problem.

To meet the low-E requirement, a low-E coated glass film 118 has to be used. The function of the low-E coating 118 is to reflect the mid-range infrared rays and reduce the heat flux through the window glass. The coating faces the inside of the room on glass surface 4 as shown in FIG. 8. The preferred low-E coating is chemical deposited over the glass. The E value 03-0.25. The preferred E value is 0.08-0.20. The most preferred E value is 0.17 or lower. The visible light transmission (VLT) of the low-E glass is 35-90%. The preferred VLT is 60-85%. The most preferred VLT is 80%. The preferred color is neutral or light green. A safety film 120 is laminated on the interior surface 103 of glass 122 to reinforce the interior glass.

The coated window glass 114 or 122 can be any type, such annealed, heat strengthened or tempered.

EXAMPLE 1

The exterior glass pane 114 uses PPG's SB60 CL-3 sputtered solar control low-E glass. The dimension is 2.5″×0.5″×⅛″ The glass has a visible light transmission (VLT) of 75.9%. The VLT is measured with a Densitometer made by Gretag Macbeth Company. The emissivity reading (E value) is 0.05. The data is obtained through an Emissometer manufactured by Devices & Service Company. The color is light yellow green with a reading of a*=−2.19, b*=2.04, and L=90.79. Where a* is CIELAB color space coordinate defining the red/green axis; b* is CIELAB color space coordinate defining the yellow/blue axis; and L is CIELAB color space coordinate defining the lightness axis. The color numbers are measured with a Spectrogard made by BYK Gardner Company. The transmission spectrum of the coated glass is measured by Lambda 900 UV/VIS/NIR spectrometer manufactured by Perkin Elmer Company. The spectrum is shown in FIG. 9.

The interior glass pane 122 uses Pilkington North America, Inc., Energy Advantage Low-E glass. It is coated on surface through a chemical vapor deposition method. The dimension is the same as the exterior glass pane. The glass has a VLT reading of 79%. The emissivity reading is 0.18. The color light neutral and yellow, a*=−, b*=1, and L=92.50. The transmission spectrum of the low-E glass is shown in FIG. 11.

A 15 mil safety film is constructed with three layers of mil clear PET film laminated to each other with an acrylic pressure sensitive adhesive. The coat weight for the laminating adhesive is 11 Ib/ream. A mounting adhesive is used to bond the 15 mil safety film and glass together. The mounting adhesive chooses the same adhesive as the laminating adhesive but has higher coat weight. It is about 16 Ib/ream. A UV absorber added into the adhesive formulation to eliminate UV spectrum from the sun.

An insulating glass unit 110 (IGU) as shown in FIG. 8 is constructed in the way described as follows. A safety film 116 is laminated to the solar control coated surface 112 of the exterior glass 114 through a laminator. A clean room environment is required. A second safety film 120 is laminated to the noncoated surface of the interior glass 122. A spacer 114 is positioned to the four edges of the first glass pane 114 over the safety film 116. The second glass pane 122 is over lapped to the first pane with safety film 120 facing the safety film 116 on the inside surface of the first glass 114. The four edges are sealed with an appropriate sealant such as buy tal or silicone sealants. The IGU is filled with argon gas 126 to improve insulation. The final construction as shown in FIG. 8 is that solar control coating 112 is on the inside surface 102 of the exterior glass 114 and the low-E coating 118 is on the exterior surface 104 of glass 122 facing the inside of a room. The safety films 116 and 120 are on the inside surfaces 102 and respectively, of glass 114 and 122.

Both the exterior solar control glass pane 112 and interior low-E glass pane 122 are laminated with a 15 mil safety film on surfaces 102 and 103 respectively, and tested with a Perkin Elmer Lambda 900 uv/vis/nir spectrometer. The emissivity number measured with a digital voltmeter. The data are input into a Window 5.0 program for analyzing window thermal performance. The software is developed by Lawrence Berkeley National Laboratory. The results are listed in Table 1. The U-value is the amount of conductive heat energy transferred through one square foot of a specific glazing system for each temperature difference between the indoor and outdoor air. The lower the U-value, the better insulating qualities of the glazing system. Solar Heat Gain Coefficient (SHGC) is measurement of the percentage of solar energy that is either directly transmitted or absorbed and then re-radiated into a building. The lower the coefficient, the better the window able to reduce solar heat.

A scratch resistance test is conducted with Taber 5130 Abraser. The test follows the ASTM D 1003 method. After 100 cycle abrasion, the delta haze for the low-E coating on the Pilkington North America, Inc., Energy Advantage low-E glass 34%. The haze is measured with BYK Gardner s Haze Gard Plus meter.

EXAMPLE 2

Exterior glass pane 114 uses Pilkington North America, Inc., Solar E glass. The dimension is 2.5″×5″×⅛″. The glass has a visible light transmission of 60.3%. The emissivity reading is 0.20. The color is blue, a*=−218, b*=−258, L=82.40. The glass has a transmission spectrum shown in FIG. 10.

The interior glass 122 uses Pilkington North America, Inc., Energy Advantage Low-E glass. Following the same process as set forth for Example 1, an IGU is made and tested. The U-value and SHGC reading are listed in table 1.

EXAMPLE 3

Exterior glass pane 114 uses PPG's SB60 CL-3 sputtered solar control low-E glass. The interior glass 122 uses Pilkington s Solar E glass. Following the same process as set forth for Example 1, an IGU is made and tested. The U-value and SHGC reading are listed in Table 1.

A scratch resistance test is conducted in the same manner as described in Example 1. After 100 cycles of abrasion testing, the solar control low-E coating is removed. The glass is clear and has less haze. The delta haze is −0.60%.

EXAMPLE 4

Both exterior 114 and interior 122 glass panes are clear glass. The dimension is the same as described in Example 1.

A 17 mil safety and solar control low-E film constructed in a way that a 2 mil sputtering coated solar control low-E film is laminated onto the 15 mil safety film with metal surface exposed. The laminating adhesive is the same acrylic pressure sensitive adhesive as previously described.

An IGU is constructed in the same way as described in Example 1. The only difference is that the 17 mil safety and solar control low-E film is laminated on the inside surface of glass 114, and the 15 mil safety film is laminated on the inside of glass 122. Both exterior 114 and interior 122 glass panes are clear glass. The U-value and SHGC are described in Table 1.

EXAMPLE 5

Both exterior 114 and interior 122 glass panes use PPG SB60CL-3 solar control low-E glass. An impact resistance unit is built the same way as described in Example 1. The only difference is that the interior glass 122 has the sputtering coated solar control and low-E coating. The U-value and SHGC are measured in Table 1. The energy performance is very good but corrosion has been found in the lab sample on a surface.

EXAMPLE 6

Exterior glass 114 uses PPG's SB60CL-3 and interior glass uses a clear glass. A safety film is laminated on the inside surfaces of glass 114 and 122. The U-value and SHGC are measured and listed in Table 1. The data shows that the glass E value is significantly weakened.

EXAMPLE 7

Weathering Test

A safety film is laminated over PPG's SB60CL-3 coating. The glass pane is tested in a QUV chamber for accelerated weathering. The glass side faces the UV lamp. The testing follows ASTM G154 methods. After 5,500 hours of exposure no corrosion or chemical reaction between the adhesive and sputtered metal is found. The glass VLT and E-value has not changed. However, the corrosion was found in the uncovered area of the low-E glass. The mounting adhesive is found slightly yellow after UV exposure.

Corrosion Test

Both Energy Advantage Low-E and Solar E glass panes are placed in a bucket filled with a little water. The bucket placed in a 135 F hot room for 14 days. No corrosion is found. Both the glasses have very good corrosion and chemical resistance. They are made through a chemical vapor deposition process.

TABLE 1
IGU energy performance data in the center of the glass:
Total VLT
No.IG Unit Construction%U-ValueSHGC
GovernmentEnergy Star Criteria≦0.35≦0.40
requirements
Example 1Glass/sb60cl-3SG1550.10.340.32
Mil/Ar/SG15
Mil/glass/EA-low E
Example 2Glass/solar E/SG1541.70.340.40
Mil/Ar/SG15
Mil/glass/EA-low E
Example 3Glass/sb60cl-3/SG1537.20.350.28
Mil/Ar/SG15
Mil/glass/solar E
Example 4Glass/17 mil solar58.90.260.35
E/Ar/SG 15 mil/glass
Example 5SB60cl-3 glass/SG1556.50.310.30
Mil/Ar/SG15
Mil/sb60cl-3
Glass
Example 6SB60cl-3 glass/SG1562.90.460.35
Mil/Ar/SG15
Mil/glass