EP0202555A1

EP0202555A1 - Environmentally controlled breather insulated window unit

Info

Publication number: EP0202555A1
Application number: EP86106329A
Authority: EP
Inventors: George Henry Bowser; Stanley Joseph Pyzewski
Original assignee: PPG Industries Inc
Current assignee: PPG Industries Inc
Priority date: 1985-05-16
Filing date: 1986-05-09
Publication date: 1986-11-26
Also published as: NZ215051A; DK225186A; AU5334386A; DK225186D0; NO860932L; AU573068B2; KR860009211A

Abstract

A multiple-glazed window unit (20) comprises a pair of glass sheets (22,24) held in spaced relation to each other by a spacer and sealant assembly (26) defining a hermetically sealed, insulating air space between the sheets. The spacer and sealant assembly (26) is provided with at least one opening (42) through at least one pair of opposed legs (50, 52) thereof to put the insulating air space in direct communication with the atmosphere external to the unit. The openings (42) are sized and configured to allow free movement of atmospheric air and water vapor molecules through the air space to equalize air space pressure and relative humidity with that of the external atmosphere. A filtering element (40) is employed to minimize infiltration of liquid water, dust, dirt, and the like through the openings and into the air space. The unit also comprises a sash for retaining the unit within a structural opening. The sash is provided with glazing pockets for holding the sealed edges of the assembled glass sheets. The base of the glazing pockets are spaced from the outer surface of the spacer and sealant assembly to provide air passageway chambers therebetween. Openings are provided through the sash to put the air chambers, and therefore, the air space, in direct communication with the external atmosphere.

Description

FIELD OF THE INVENTION

The present invention relates generally to multiple-glazed window units and more particularly, to multiple-glazed units having their insulating air space in fluid communication with the atmosphere external to the unit.

BACKGROUND OF THE INVENTION

Multiple-glazed, insulating window units usually consist of two (or more) panes of glass maintained in spaced, parallel relation to each other by a spacing and sealing assembly which is structurally bonded to the marginal edge periphery of the opposed, inner or facing surfaces of the glass panes to define an insulating airspace between the panes. The spacing and sealing assembly generally hermetically seals the airspace from the environment. However, the spacing and sealing assembly generally contains a desiccant material or dehydrator agent adapted to adsorb moisture or water vapor which may be present in the airspace when the glass panes are assembled or which may later form by condensation within the airspace, to ensure dryness of the airspace to prolong the useful life of the unit and to enhance the performance quality thereof. Representative examples of multiple-glazed, insulating window units are taught in U.S. Patent Nos. 2,306,327; 2,838,810; 3,280,523; 3,733,237; 3,791,910; 4,226,063; and 4,348,435, which teachings are herein incorporated by reference.
However, sealed, insulating window units of the above-discussed type are frequently subjected to deflection of the glass panes due to pressure differential between the air space and the exterior atmosphere. The pressure differential may be caused in a multiplicity of ways. One cause is by the atmospheric pressure whereat the window unit is installed being different than the pressure conditions which existed when the unit was sealed. The pressure differential can also be caused by large temperature differences between the air space and the exterior atmosphere, e.g. during large atmospheric temperature changes. Large atmospheric pressure changes may also cause this pressure differential. When the pressure between the panes is less than the exterior pressure, the panes are forced closer together. Conversely, when the pressure in the space exceeds the exterior pressure, the panes are forced apart. Appreciable deflection of the panes can cause optical distortion of the window unit and can also present an undesirable cosmetic effect. Further, deflection places stress on the spacing and sealing assembly which gradually weakens the adhesive bond between the glass surfaces and the spacing and sealing assembly. This phenomenon may result in leakage and infiltration of relatively moist exterior air into the insulating air space, ultimately causing satiation and exhaustion of the desiccant contained by the spacer element. When the desiccant is exhausted, it is no longer capable of adsorbing the moisture-vapor present in the air space, and condensation of the moisture-vapor begins to occur on the glass surfaces contacting the air space (i.e. interior glass surfaces). More specifically, the moisture-vapor forms a molecular film of water on the interior glass surfaces. The molecular film absorbs or leaches molecules or ions from the glass surfaces. This leaching phenomenon is evident/is manifested as scum or stain on the interior glass surfaces, which imparts an undesirable white hazy or foggy appearance to the window unit.
Multiple-glazed window units are presently available for minimizing the above-discussed deflection and desiccant saturation problems. One such unit is taught in U.S. Patent No. 3,838,809, assigned to the assignee of the present invention. In accordance with the aforementioned patent, a multiple-glazed unit is constructed comprising a plurality of glass sheets separated at their marginal edges by a hollow spacer element containing a desiccant material, an elongated strip of mastic in sealing contact with the edges of the glass sheets and the spacer element and a pressure sensitive tape covering the strip of mastic. The unit is provided with an aperture or aligned opening through the tape, mastic and outer wall of the spacer element, to connect the atmosphere with the desiccant and at least one other opening through the inner wall of the spacer element communicating with the insulating air space of the unit. The aligned openings or apertures permit the unit to "breathe" through the desiccant material in response to changes in atmospheric conditions. U.S. Patent No. 3,771,276, also assigned to the assignee of the present invention, teaches a multiple-glazed unit having a breather device comprised of a capillary tube connected to a column of desiccant, so that a free end of the capillary tube is disposed in open communication with the air surrounding the unit (i.e. the exterior atmosphere) while the desiccant column, to which the capillary tube is fluidly connected at its opposite end, is in communication with the enclosed, insulating air space of the unit. In operation, the breather unit works in the following manner. When the exterior atmospheric pressure exceeds the air pressure of the insulating air space, e.g. due to a nighttime temperature drop, then air flows from the exterior atmosphere, through the capillary tube and the desiccant column, and thenceforth, into the insulating air space. During this inflow of the exterior atmospheric air, moisture contained in the entering air is adsorbed by the desiccant. Further, the air space pressure and the exterior atmospheric pressure are equalized, thereby preventing deflection of the opposed glass panes. Conversely, when the air pressure of the insulating air space exceeds the pressure of the exterior atmospheric air, e.g. due to warmed air expansion during daytime hours, then air flows from the insulating air space, through the desiccant column and the capillary tube, and thenceforth, into the exterior atmosphere. The warm, outflowing air desorbs the previously adsorbed moisture from the desiccant, thereby regenerating the desiccant and extending its useful life. Further, the air space pressure and the exterior atmospheric pressure are equalized, thereby eliminating deflection of the glass panes. U.S. Patent No. 4,435,796 issued to Schoofs discloses a similar insulating glass unit with a breather device for minimizing deflection of the glass panes and maximizing the useful life of the desiccant.
All of the above-discussed presently available insulating window units having a breather device suffer from the common disadvantages of being more difficult and expensive to fabricate than conventional multiple-glazed window units.
It would be advantageous to have a "breather-type" multiple-glazed window unit of an alternative design, and which is preferably, less expensive to manufacture than the presently available units.

SUMMARY OF THE INVENTION

The present invention, in one embodiment, comprises a window unit having two (or more) sheets, e.g. glass panes, maintained in spaced relationship to each other by a spacing and sealing assembly bonded to the marginal edge periphery of the inner facing surfaces of the panes, to define an insulating air space therebetween. The spacing and sealing assembly or "edge packing" preferably contains no desiccant or adsorbent material, thereby reducing the costs of fabricating or manufacturing the window unit. In accordance with a preferred embodiment of the present invention, opposed portions of the spacing and sealing assembly are each provided with at least one and preferably at least two breather holes, to put the insulating air space in fluid communication with the atmosphere outside of the window unit. The breather holes are positioned to enable free, unobstructed, unimpeded movement of outside air and water vapor molecules through the breather holes of one assembly portion, through the insulating air space and thenceforth through the breather holes of the opposed assembly portion, and back into the outside atmosphere, to thereby provide a continuous moisture-vapor transmission path from the outside atmosphere, through the insulating air space, and back to the outside atmosphere. A filtering medium preferably covers the breather holes to filter out dust, dirt, liquids, and other contaminants, to prevent their ingress or migration into the insulating air space. The breather holes function to allow rapid equalization of the pressure of the atmosphere within the insulating air space and the atmospheric pressure outside of the window unit, to prevent or minimize deflection or bowing of the glass panes. Further, free circulation or movement of outside air and water vapor molecules into and out of the insulating air space minimizes the trapping of these molecules within the air space and thereby minimizes condensation and/or moisture buildup within the air space, even during periods of drastic or unusual changes of temperature and/or relative humidity conditions in the outside atmosphere.
The present invention also contemplates a frame means or sash for retaining the window unit within a window opening provided in a structure.
The sash has a glazing pocket or recess for receiving the marginal edges of the multiple-glazed window unit. Portions of the sash which correspond to the portions of the edge packing provided with the breather holes, are spaced from the outer surface of the corresponding portion of the edge packing, to form an air passageway channel or chamber therebetween. At least one hole is provided through the sash portions corresponding to the portions of the edge packing having the breather holes, to put the insulating airspace in communication with the atmosphere external to the window unit, via the air passageway channels, to thereby establish a continuous transmission path for free air and water vapor molecular flow through the insulating air space. The present invention also encompasses means associated with the atmosphere communicating holes for filtering dust, dirt, liquids and the like to prevent or minimize their ingress or migration into the air passageway chambers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective, partially cutaway view of a multiple-glazed window unit embodying features of one embodiment of the present invention.
FIG. 2 is a perspective, partially cutaway view of a multiple-glazed window unit embodying features of another embodiment of the present invention.
FIG. 3 is a fragmentary, cross-sectional view of the window unit of FIG. 2 taken along the line III-III in FIG. 2.
FIG. 4 is a perspective view of a multiple-glazed window unit embodying features of another embodiment of the present invention.
FIG. 5 is a perspective view of the window unit of FIG. 1 installed within a sash embodying further features of the present invention.
FIG. 6 is a fragmentary, cross-sectional view of the composite sash and window unit of FIG. 5 taken along the line VI-VI in FIG. 5.

DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, there can be seen a multiple-glazed window unit 20 having a pair of sheets 22, 24 maintained in spaced relation to each other by a spacer and sealant assembly 26 defining an insulating air space 28 between the sheets 22, 24. The type of sheets 22, 24 employed is not limiting to the invention. For purposes of the following discussion, the sheets 22, 24 are transparent sheets made of, e.g., glass or plastic. However, either or both of the sheets 22, 24 may be rendered opaque by a suitable opacifier, e.g. such as taught in U.S. Patent No. 4,000,593 issued to Cypher, which teachings are herein incorporated by reference, to thereby provide a spandrel unit. Further, the sheets 22, 24 may have any desired optical, thermal, safety, aesthetic, or solar control properties. For example, either or both of the sheets 22, 24 may be tinted or colored glass, e.g. such as the glass sold by PPG Industries, Inc. under their registered trademarks SOLARBRONZE@, SOLARGRAY@, or SOLEX®. Further, either or both of the sheets 22, 24 may be coated as taught in U.S. Patent No. 4,000,593, which teachings are herein incorporated by reference, such as with metallic or metallic oxide reflective films or coatings, e.g. such as the type of coatings applied to multi-glazed units sold by PPG Industries, Inc. under their registered trademarks NESA®, SOLARBAN 560-14@, or SOLARBAN 570-30@. Yet further, either or both of the glass sheets 22, 24 may be laminated, heat strengthened, or tempered for safety or other purposes.
The type of spacer and sealant assembly employed in the practice of this invention is also not limiting to the invention. Any convenient type of metal or non-metal spacer-sealant assembly may be used in the practice of this invention. Suitable metal spacer-sealant assemblies which may be used in the practice of this invention include, but are not limited to, those taught in U.S. Patent Nos. 2,306,327; 2,838,810; 2,684,266; 3,280,523; and 3,919,023, all of which are assigned to the assignee of this invention, which teachings are all herein incorporated by reference. Suitable non-metal spacer-sealant assemblies which may be used in the practice of this invention include, e.g., those taught in U.S. Patent Nos. 3,669,785; 4,109,431; and 4,215,164, which are assigned to the assignee of the present invention, and in U.S. Patent Nos. 4,198,254; 4,205,104; and 4,226,063, which teachings are also herein incorporated by reference.
Referring still to FIG. 1 and additionally to FIG. 3, a preferred embodiment of the present invention comprises a pair of transparent glass sheets 22, 24 held in spaced relation to each other by a hollow, metal spacer 30 made of extruded aluminum, steel or any other suitable material, extending around the inner, marginal peripheries of the glass sheets 22, 24. A moisture-resistant mastic layer 32, e.g. such as the type taught in U.S. Patent No. 3,791,910 issued to Bowser, which teachings are herein incorporated by reference, adheres the spacer 30 to the glass sheets 22, 24, to thereby form the enclosed chamber or insulating air space 28. In this preferred embodiment, no desiccant or absorbent material is put into the hollow interior of the spacer 30, to thereby reduce manufacturing costs and complexity. If a non-metal spacer such as taught in U.S. Patent Nos. 3,669,785; 4,109,431; or 4,215,164 is employed, the desiccant material is left out of the polymeric matrix spacer composition, thereby eliminating the costs associated with adding it to the polymeric matrix. A fine mesh screen, e.g. a cloth, fabric, or stainless steel screen 40 having an adhesive applied to at least one side thereof, is applicated to the outer periphery of the spacer 30. The fine mesh screen 40 may suitably be a venting tape of the type sold by 3M Company. A ribbon or layer 34 of adhesive sealant material is preferably adhered to the outer periphery of the venting tape 40 and the inner marginal peripheries of the glass sheets 22, 24. The outer, sealant layer 34 may suitably be of the type taught in U.S. Patent Nos. 4,348,435; 2,306,327; or 3,791,910. The outer sealant layer 34 should form a resilient, firm, adhesive structural bond to maintain the desired spacing between the sheets 22, 24. The inner, mastic layer 32 and the spacer 30 preferably provide a primary hermetic seal and the outer, sealant layer 34 preferably provides a secondary hermetic seal, to minimize migration or penetration of moisture or water vapor into the insulating air space 28. Thereafter, a channel member (not shown), such as disclosed in U.S. Patent Nos. 2,838,810; 2,964,809; and 3,280,523, can be affixed around the periphery of the unit 20 to protect the edge periphery of the sealant layer 34. Alternatively, as can be seen in FIG. 3, a durable material, e.g. polyethylene tape 44 is applied around the outer periphery of the sealant layer 34 and the peripheral edges of the glass sheets 22, 24 to protect the same.
In accordance with a preferred embodiment of the present invention, aligned openings 42 are provided through the protective tape 44, the sealant layer 34, the venting tape 40, and the front wall 46 and the back wall 48 of the spacer 30, to thereby put the insulating air space 28 in direct communication with the ambient atmosphere surrounding the window unit 20. As shown in FIG. 1, the openings 42 preferably comprise breather holes 42 located at opposite corner portions of the vertical legs 5& of the spacer and sealant assembly 26. Alternatively, referring now to FIG. 2, the breather holes 42 are located at opposite corner portions of the horizontal legs 52 of the spacer and sealant assembly 26. In another alternative embodiment of this invention, as can be seen in FIG. 4, the openings 42 comprise a breather hole 42 at a central portion, e.g. the midpoint, of each of the legs 50 and 52 of the spacer and sealant assembly 26. It should be understood that the size, type, shape, location, and/or configuration of the openings 42 are not limiting to the present invention. The openings 42 may suitably be, e.g., slits, slots, apertures, or holes of any shape, e.g. oval, circular, elliptical, triangular, rectangular, polygonal, etc. For example, the openings 42 may comprise slots (not shown) provided through the four corners of the spacer and sealant assembly 26. The only criterion for the size, shape, and location of the openings 42 is that they collectively or cooperatively function to provide a direct moisture-vapor molecular transmission path from the ambient atmosphere, through the insulating air space 28, and back to the ambient atmosphere. This free, circulatory flow or movement of water vapor molecules into and out of the air space 28 prevents or minimizes condensation on the glass sheets 22, 24 by minimizing the trapping of these molecules within the air space 28. Further, this free movement of air and water vapor molecules into and out of the air space 28 enables rapid equalization of the pressure and relative humidity between the air space 28 and the ambient atmosphere. Rapid equalization of the pressure in the air space 28 with the pressure of the ambient atmosphere minimizes the edge stresses imposed on the spacer and sealant assembly 26 by deflection of the glass sheets 22, 24 due to pressure differences between the air space 28 and the ambient atmosphere. Rapid equalization of the relative humidity in the air space 28 with the relative humidity of the ambient atmosphere minimizes condensation in the air space 28 due to fluctuations of atmospheric humidity conditions. It is believed, based on testing of window units made in accordance with the teachings of this invention, that maximum free movement of air and water vapor molecules through the air space 28 occurs when the breather holes 42 are located substantially directly opposite each other.
Referring now to FIG. 6, there can be seen a window unit 20 encompassed and retained by a sash 60 to facilitate installation of the composite window and sash 62 into a window opening (not shown) provided in a structure (not shown) whereat the unit is to be installed. The type of sash 60 used is not limiting to the present invention as any convenient frame means may be employed, e.g. a wood or metal frame, e.g. of the type taught in U.S. Patent No. 3,932,971 issued to Day, which teachings are herein incorporated by reference. The window unit 20 comprises breather holes 42 through opposite corner portions of the vertical legs 50 of the spacer and sealant assembly 26, as shown in FIG. 1. The sash 60 comprises horizontal sash members 64 and vertical sash members 66 joined at their ends so as to form a generally rectangular enclosure or frame conforming to the perimetrical shape of the window unit 20. Referring additionally to FIG. 5, each of the sash members 64 and 66 has a longitudinally extending channel recess or glazing pocket 68 sized to receive and capture the corresponding edges of the window unit 20. In order to ensure a snug fit and to environmentally seal the glazing pockets 68, a resilient, e.g. rubber, neoprene, or silicone gasket (not shown), weatherstripping (not shown), caulking (not shown), or the like, is preferably applied in a convenient manner, as is widely known and practiced in the pertinent art, between the inside walls of the glazing pockets 68 and the outer marginal edge surfaces of the glass sheets 22, 24; around the entire periphery thereof. Intermittent setting blocks (not shown) may be provided within the glazing pocket 68 of the lower horizontal sash member 64 to support the window unit 20 in a vertical position within the sash 60, in the normal manner, as is already well known in the pertinent art. In accordance with the present invention, the base 70 of the glazing pockets 68 of at least the vertical sash members 66 are spaced from the outer surface of the corresponding vertical legs 50 of the spacer and sealant assembly 26 of the window unit 20, to provide a longitudinally extending vertical air passageway channel or chamber 72 between the base 70 of the glazing pockets 68 of the vertical sash members 66 and the outer surface of the corresponding vertical legs 50 of the spacer and sealant assembly 26. Further, one or more openings 74 are provided through the outer face or wall 76 of the vertical sash members 66 to put the chambers 72 in direct communication with the ambient atmosphere around the composite window and sash 62. Therefore, since the chambers 72 communicate with the air space 28 via the breather holes 42, the openings 74 serve to communicate the air space 28 with the ambient atmosphere, thereby enabling rapid equalization of the pressure and relative humidity of the air space 28 and the ambient atmosphere. In order to maximize air and water vapor molecular flow through the air space 28, the atmosphere communicating openings 74 are preferably located in close proximity to the location of the corresponding breather holes 42 through the corresponding legs of the spacer and sealant assembly 26. Most preferably, the openings 74 are disposed substantially horizontally adjacent to their corresponding breather holes 42. More particularly, with reference to FIG. 6, if the breather holes 42 are provided through opposite corner portions of the vertical legs 50 of the spacer and sealant assembly 26, then the atmosphere communicating openings 74 are preferably provided through corresponding opposite corner portions of the outer face or wall 76 of the vertical sash members 66, to maximize free air and water vapor molecular flow through the insulating air space 28. Similarly, if the breather holes 42 are provided through opposite corner portions of the horizontal legs 52 of the spacer and sealant assembly 26, then the atmosphere communicating openings 74 are preferably provided through corresponding opposite corner portions of the outer face or wall 76 of the horizontal sash members 64. In the latter instance, the base 70 of the glazing pockets 68 of the horizontal sash members 64 must be spaced from the outer surface of the corresponding horizontal legs 52 of the spacer and sealant assembly 26 to provide a longitudinally extending air passageway channel or chamber (not shown) between the base 70 of the glazing pockets 68 of the horizontal sash members 64 and the outer surface of the corresponding horizontal legs 52 of the spacer and sealant assembly 26. It should be clearly understood that the size, shape, location, type, and/or configuration of the openings 74 are not limiting to the present invention. The openings 74 may suitably be, e.g. slits, slots, apertures, or holes of any shape, e.g. oval, circular, elliptical, triangular, rectangular, polygonal, etc.
Referring still to FIG. 6, the openings 74 are preferably shielded from the external environment by means of a suitable water or weather barrier means, e.g. generally arcuate or canopy-shaped members (not shown) which are conveniently attached, e.g. mechanically fastened or welded, to the outer face or wall of the sash members 64 and/or 66 with which the openings 74 are associated. The canopy-shaped members are preferably disposed in spaced, shielding relation to at least a portion of their associated openings 74, to minimize infiltration of liquid water and the like through the openings 74, by minimizing the amount of water allowed to reach the openings 74. Further, a fine mesh screen (not shown) made of any suitable material, e.g. mylar, fabric, or metal, is preferably provided in direct covering relation to the holes 74 to function as a filtering medium to further minimize ingress of liquid water, dirt, dust, etc. through the openings 74 into the vertical chambers 72 and/or the horizontal chambers (not shown).

DETAILED DESCRIPTION OF TEST EMBODIMENTS OF THE PRESENT INVENTION

Several window units 20 were constructed in accordance with the teachings of the present invention for purposes of field testing. More particularly, with reference to FIGS. 1, 5 and 6, sixteen window units 20 having breather holes 42 through opposite corner portions of the vertical legs 50 of the spacer and sealant assembly 26 were built. The glass sheets 22, 24 each comprised a sheet of float glass having the tin or float bath-side thereof facing the insulating air space 28. The insulating air space 28 was 1/2 inch (1.27 cm.) thick. The window units 20 were of the same basic construction as the multi-glazed window units sold by PPG Industries, Inc. under their registered trademark TWINDOW®, except that the metal spacer 30 contained no desiccant or absorbent material, i.e. it was hollow. The vertical legs 50 were about two (2) feet (70.5 cm.) long and the horizontal legs 52 were about four (4) feet (122.5 cm.) long. The breather holes 42 were about 1/8 inch (.32 cm.) in diameter and located approximately one (1) inch (2.54 cm.) from the corners of the vertical legs 50. The moisture-resistant mastic layer 32 comprised an adhesive sealant layer like that taught in U.S. Patent No. 3,791,910. The fine mesh screen 40 used to cover the breather holes 42 was 3M Company Y394 Venting Tape@ which was held in fixed relation to the spacer 30 by a silicone-based adhesive sealant sold by General Electric under their trademark GE 3204@. The sealant layer 34 comprised a bead of GE 3204@ sealant applied around the outer periphery of the venting tape 40 to form, in effect, a continuous glue cleat, to maintain the desired spacing between the sheets 22, 24.
The atmosphere-communicating openings 74 were located about one inch (2.54 cm.) from the opposite corners of the vertical sash members 66. The vertical air chamber 72 and the horizontal air chamber (not shown) were about 1/4 inch (.64 cm.) in width, i.e. a clearance of approximately 1/4 inch (.64 cm.) was provided between the base 70 of the glazing pockets 68 and the outer peripheral surfaces of the spacer and sealant assembly 26 around the entire periphery thereof. The openings 74 were circular and had a diameter of about 3/8 inches (.95 cm.). The openings 74 were covered by a fine mesh stainless steel screen (not shown) and weather-shielded by canopy-shaped members (not shown) welded to the outer face of the-vertical sash members 66 in spaced, covering relation to the openings 74. The 16 units 20 were then installed in a home in western Pennsylvania. The units have been on test for about one year and have not displayed any visible fog, haze, condensation, scum, stain, or the like over this period. Several additional test sample double-glazed window units of the standard TWINDOWO unit construction (except Sample No. 6) were tested at about 140°F (77°C), 90% relative humidity, in a controlled laboratory environment, over a one week testing period. The Sample No. 1 unit had one breather hole through the midpoint of one of the legs of the spacing and sealing assembly thereof. The Sample No. 2 unit had one breather hole through each of two adjacent legs of the spacing and sealing assembly thereof. The Sample No. 3 unit had a breather hole through each of three adjacent legs of the spacing and sealing assembly thereof. The Sample No. 4 unit had a breather hole through each of two opposite legs of the spacing and sealing assembly thereof. The Sample No. 5 unit was constructed in accordance with the alternative embodiment of the present invention shown in FIG. 4. The Sample No. 6 unit comprised two sheets of clear float glass held apart only by a continuous strip of 3M Y-394 Venting Tape@ applied around the entire edge periphery of the spaced sheets. Light transmission and haziness of the units were determined by measurements made with a Hunter model D554 instrument, after the one week testing cycle was completed. The results are shown in the following Table 1. The control figures are for the standard TWINDOW® unit with no holes.
Although the present invention has been described in some detail with regard to some embodiments thereof, it should be clearly understood that the present invention is not limited thereto, and that many variations and/or modifications may appear to those in the art without departing from the spirit and scope of the invention. For example, the breather holes 42 may be located in an almost infinite number of locations or configurations, depending upon the size of the unit 20, the thickness of the air space 28, and the size and shape of the holes 42, amongst a host of other variable parameters. The holes 42_"may be, e.g. located right through the corners of the unit; at the midpoint of the legs of the spacer and sealant assembly; 2-1/2 inches (6.35 cm.) from the corners, or in any other position which enables free movement of air and water vapor molecules through the air space 28. Similarly, the location, size, and configuration of the atmosphere-communicating openings provided through the sash members may be varied in a virtually endless number of ways. The scope of this invention should be determined solely on the basis of the following claims.

Claims

1. A multiple-glazed unit, comprising:

a pair of sheets;

spacing and sealing means having a pair of opposed horizontal legs and a pair of opposed vertical legs joined at their ends to form a sealed enclosure between said sheets for maintaining said sheets in spaced relation to each other and defining an at least substantially hermetically sealed insulating air space between said sheets; and

at least one opening provided completely through each said leg of at least one of said pairs of opposed legs of said spacing and sealing means to put said insulating air space in direct communication with the atmosphere external to the unit.

2. The unit as set forth in claim 1, wherein it further comprises means for minimizing the ingress of liquid water, dust, dirt, or the like through said openings into said insulating air space.

3. The unit as set forth in claim 2, wherein said minimizing means comprises a fine mesh filtering element disposed in covering relation to said openings.

4. The unit as set forth in claim 2, wherein said openings cooperatively function to provide a direct moisture-vapor molecular transmission path from the external atmosphere, through said insulating air space, and back into the external atmosphere.

5. The unit as set forth in claim 4, wherein said openings comprise an opening through opposite corner portions of said vertical legs of said spacing and sealing means.

6. The unit as set forth in claim 4, wherein said openings comprise an opening through opposite corner portions of said horizontal legs of said spacing and sealing means.

7. The unit as set forth in claim 4, wherein said openings comprise an opening through a central portion of said horizontal and said vertical legs of said spacing and sealing means.

8. The unit as set forth in claim 2, wherein said spacing and sealing means contains no desiccant or dehydrator material.

9. The unit as set forth in claim 2, wherein said openings each comprise generally circular holes having a diameter of between about 1/32 inches (.08 cm.) and 1/4 inches (.64 cm.).

10. The unit as set forth in claim 2, wherein said spacing and sealing means comprises:

a spacer element bonded to the opposed marginal edge peripheries of said sheets;

an adhesive sealant layer disposed around the periphery of said spacer element in sealing engagement with the opposed marginal edge peripheries of said sheets, wherein said adhesive sealant layer forms a resilient, adhesive structural bond with said sheets to maintain said sheets at a desired spacing; and

wherein said openings each comprise aligned openings provided completely through said sealant layer and said spacer element.

11. The unit as set forth in claim 10, wherein said spacer element is made of metal.

12. The unit as set forth in claim 10, wherein said spacer element is made of a non-metal material.

13. The unit as set forth in claim 10, wherein said sealant layer comprises a silicone-based material.

14. The unit as set forth in claim 11, wherein said spacer element is bonded to the opposed marginal edge peripheries of said sheets by means of a moisture-resistant mastic.

15. The unit as set forth in claim 2, wherein it further comprises a frame means for retaining the unit within a structural opening, wherein said frame means comprises:

a pair of horizontal sash members and a pair of vertical sash members joined at their ends to form a frame disposed in circumscribing relation to said spacing and sealing means, wherein each of said sash members comprises a longitudinally extending glazing pocket adapted to receive and retain the sealed edges of said assembled sheets;

wherein the base of said glazing pocket of at least said sash members corresponding to said legs of said spacing and sealing means provided with said at least one opening, is spaced from the outer surface of said aforesaid legs to provide longitudinally extending air passageway chambers between the outer surface of at least said legs of said spacing and sealing means provided with said at least one opening and the base of said glazing pocket of the corresponding sash members; and

at least one opening provided through each said sash member of at least one pair of opposed sash members to put said air passageway chambers in direct communication with the external atmosphere.

16. The unit as set forth in claim 15, wherein said openings provided through said sash members cooperatively function to permit the free movement of air and water vapor molecules from the external atmosphere through said air passageway chambers, said openings provided through said legs of said spacing and sealing means and said insulating air space, and back into the external atmosphere.

17. The unit as set forth in claim 16, wherein said openings provided through said sash members are located substantially adjacent to said openings provided through said legs of said spacing and sealing means.

18. The unit as set forth in claim 16, wherein it further comprises means for minimizing the ingress of liquid water, dust, dirt, or the like through said openings provided through said sash members into said air passageway chambers.

19. The unit as set forth in claim 18, wherein it further comprises weather shielding means disposed in spaced, at least partially covering relation to said sash member openings, for minimizing the amount of liquid water allowed to reach said sash member openings.

20. A multiple-glazed unit, comprising:

a pair of sheets;

a spacer mounted between said sheets to maintain the sheets in spaced relation to define an airspace therebetween;

means to secure said spacer to said sheets and hermetically seal said airspace; and

an opening in each of opposed portions of said spacer to provide for free movement of ambient air and water vapor molecules into, through, and out of said airspace.