WO2001081700A1 - Enhanced window frame assembly and method - Google Patents

Abstract

A window frame assembly (10) for supporting a window pane (11) where the preferred window frame assembly is attached to one or more building surfaces (13, 13a, 13b), including at least one window frame element (12, 14, 14a, 16) sealably connected to a perimeter area of the window pane forming a framed window subassembly and a building frame element (19, 19a, 19b) having an air hole (23, 23a, 23b) for substantially equalizing air pressure proximate to either side of the air hole, wherein the building frame element is fastened to a building surface using a fastener (18, 18a, 18b). The air hole has a cross-sectional area at least about 0.1 square inches. The preferred embodiment also includes a slidable window to frame attachment and sealing and a cover frame element (40, 40a) to allow easier window assembly installation and removal as well as limit unintentional removal.

Description

ENHANCED WINDOW FRAME ASSEMBLY AND METHOD

SPECIFICATION

Prior Application

This Application is a Continuation-in-part of copending U.S. Patent Application Serial No. 08/887,879, filed on July 3, 1997 and entitled Air Loop Window System and co-pending PCT Patent Application Serial No. PCT/US00/11692, filed on April 26, 2000 and entitled Enhanced Curtain Wall System. The prior filed co- pending applications are incorporated herein in their entirety by reference.

Field of the Invention

This invention relates to panel assemblies in buildings, specifically to an improvement to fixed window frame structures and installation/removal methods in buildings with pre-cast concrete, stucco, or other structural materials adjacent to window openings. More specifically, the invention relates to an improved window frame apparatus and method which allows simplified window installation/removal from inside the building after the window frames are attached and improves the resistance to water leakage. Background

In addition to providing an aesthetic appearance and/or view for the sides of buildings, some of the major performance objectives of panel assemblies and more specifically fixed window and window frame assemblies are as follows : to provide a barrier or at least resistance to excessive amounts of exterior air infiltrating around a window into one or more interior environments within the building; to provide a barrier or at least resistance to excessive amounts of exterior rain or other exterior liquids/particles infiltrating around a window into one or more interior spaces within the building; to provide resistance to structural loads, specifically including supporting the weight of the windows and resisting seismic loads, wind loads, and thermal expansion/contraction loads, if any; and to provide a thermal barrier or at least resistance to excessive heat transfer between the exterior air and one or more interior environments.

The cost of installing, maintaining, and replacing prior art windows in a large commercial building is not insignificant. Costs can result from the need to install fixed windows from outside the the building, time consuming and costly sealing of window panels in the field, and providing cleaning, repair, maintenance, and other access to the fixed windows, especially access to the exterior surface of the window and/or window frame. As used herein, a window or window panel will typically mean a fixed window not frequently opened or removed by tenants, e.g., not normally used for cleaning access, ventilation, or egress.

And despite the high initial installation and maintenance costs, prior window panel and frame systems may still allow excessive air and/or rain water to get 0 into the building, e.g., after seal degradation and under extreme wind conditions or structural loadings due to single-event extreme loads such as seismic events. In addition, dynamic cycles of positive and negative wind loads (e.g., winds and/or wind loads directed towards and

... away from the building interior on one side of the building) , daily thermal expansion and contraction, and other daily ventilation and other equipment operation may cause loosening of building attachment means, structural fatigue failures, and hysteresis loss of seal

„_n compression, resulting in still further damage and water leakage .

In addition, prior art window frames may not provide the desired thermal insulation for some applications. Although double pane windows may be used,

25 an aluminum frame can provide a high thermal conductivity path for heat transfer instead of thermal insulation. Still further, seismic and other loads that may not cause direct failure, may tend to crack or loosen window panes and damage window seals causing additional heat transfer and other problems, especially if the windows are improperly installed or the building structure is slightly deformed. Thus, although significant advancements have been made in achieving some objectives for a window frame system, an improved system is still needed.

o Summary of the Invention

A preferred embodiment of an enhanced window frame assembly for supporting a window pane is attached to one or more building surfaces, the window frame assembly including at least one window frame element c sealably connected to a perimeter area of the window pane forming a framed window subassembly and at least one secured frame element having an air hole for substantially equalizing air pressure proximate to either side of the air hole wherein the secured frame element is _Q fastened to a building surface. In the preferred embodiment, the cross-sectional area of said air hole is at least about 0.1 square inches or a hole having a diameter of about 3/8 inch. The enhanced window frame assembly can also include one or more of the following _ι- features: an inner air loop space and an outer air loop space that separates water and air seals, an air entry opening sufficient to equalize the pressure in an air air loop with the exterior environment and having baffles to create a circuitous path near the air entry opening to limit water entry into at least one of the air loops, a slidable window subassembly to perimeter frame attachment and sealing, structural retention of a framed window subassembly within a secured frame element for sealing and resisting positive (inward directed) and negative (outward) wind loads, thermal breaks in one or more frame elements to increase the resistance to heat transfer _Q between the building interior and the exterior environment, and cover frame elements to allow easier window assembly installation and removal but limit unintentional removal .

c Brief Description of the Drawings

Figure 1 is a front view of an exterior wall system portion including an embodiment of the enhanced window frame assembly;

Figure 2 is a partial cross-sectional view taken _Q - along line 2-2 of Figure 1 showing a horizontal upper wall joint of an embodiment of the enhanced window frame assembly;

Figure 3 is a partial cross-sectional view taken along line 3-3 of Figure 1 showing a vertical wall joint ₅ of an embodiment of the enhanced window frame assembly;

Figure 4 is a partial cross-sectional view taken along line 4-4 of Figure 1 showing a horizontal lower wall joint of an embodiment of the enhanced window frame assembly; and

Figure 5 is a partial cross-sectional view taken along line 5-5 of Figure 1 showing a vertical window to window joint of an embodiment of the enhanced window frame assembly.

In these Figures, it is to be understood that like reference numerals refer to like elements or features .

Description of the Preferred Embodiment of the Invention

In order to better explain the working principles of the invention, the following terminology will be used herein: a window: a glass or other limited-load supporting wall element of a building wall secured and nominally sealed to a window frame; an inner air loop : an air space substantially forming a loop around and near the perimeter edges of the glass elements and generally within the window frame; an outer air loop: an air space substantially forming a loop around each glass element proximate to the inner air loop; a water seal: a sealant line in an exterior water path towards an interior space within the building for restricting water infiltration when little or no differential air pressure is present across the sealant line ; and an air seal: a sealant line inboard and spaced-apart from a water seal for restricting air infiltration into the building.

Figure 1 illustrates a portion of an embodiment of the enhanced window assembly or system 10 typically comprising at least one substantially fixed window panel or other panel element 11 that is nominally supported in a vertical plane and sealably attached to an upper window joint and secured frame assembly 12 and/or other frame assembly elements (e.g., other secured frame elements or joints 14, 14a, and 16 that are attached to a floor slab surface or other building elements 13. Although Figure 1 shows an embodiment of an enhanced window assembly 10 in which a plurality of panel elements 11 are preferably composed of a multi-pane glass or other transparent material, the enhanced window system can also comprise translucent, decorative, or other panel materials. And although the edges of window panels 11 shown in Figure 1 are substantially oriented in horizontal and vertical directions and the edge shapes are generally square and flat, other orientations, types, and shapes of panels may also be used. But however the individual panels are shaped or oriented, the panels must be joined together or to a portion of a building, typically using window frame elements at the building and/or panel joints. Alternative types of enhanced window systems include porthole or other circular-edged openings in building surfaces. Many of the enhanced window frame elements can also be applied to openable windows and ports including louvered windows, casement windows, double-hung windows, and sliding windows.

Although the preferred embodiment of the enhanced window frame assembly is shown attached to adjacent precast concrete floor portions of a building, alternative embodiment can be attached to other buildings or other building elements. Other building portions that the enhanced window frame may be attached to include roofs, atriums, basements, and concrete block walls.

Four types of window frame joints are typically formed between adjacent panel elements or a panel element and a portion of the building, namely a nominally horizontal upper window-wall joint 12 (also shown in

Figure 2) , a nominally vertical window-window joint 15

(also shown in Figure 5) a nominally vertical window-wall joint 14 or 14a (also shown in Figures 1 & 3) , and a nominally horizontal lower window-wall joint 16 (also shown in Figure 4) . However, many other types of wall and window joints can be formed and used, e.g., nonlinear joints, linear joints oriented at a diagonal or other direction, or joints made to accommodate wall protrusions or irregular glass panel boundary geometries. In Figure 2, an upper building anchor or secured perimeter frame element 19 of the upper frame assembly 12 is shown attached to a lower edge of a pre-cast concrete floor, panel, or other building element 13 using a building screw or other fasteners 18 through passageways preferably separate from the air hole 23. Although a hex head building screw 18 is shown in Figure 1, alternative embodiments may use other fasteners or other means for attaching, e.g., bolts, clips, studs, adhesives, weldments, clamps, and hooks.

In the preferred embodiment, the one or more air holes 23 has a cross-sectional area of at least about 0.1 square inches. In alternative embodiments, the air hole 23 may have a cross-sectional area in a plane perpendicular to the plane of Figure 2 that ranges from about 0.2 square inches to about 1.5 square inches. In^' an alternative embodiment, the fastener 18 passes through air hole 23 and the cross-sectional area of the air hole is increased to accommodate the nominally circular cross- sectional area of the fastener within the air hole.

The top perimeter frame or anchor element 19 is shaped to form an inner air loop portion or upper building space 24 between the upper anchor element and the building 13. The air pressure inside the inner air loop portion 24 is essentially equalized with the air pressure in the outer air loop portion 21 and in the exterior environment E outside the building 13 with air exchange through air hole 23. The pressure equalization on both the exterior and interior sides of a building or anchor water seal 22 allows the building water seal to function as a water barrier or restrictor even when water is present on the water seal and/or on the exterior surface ES of the upper perimeter element 19 and the anchor water seal 22 is imperfect . Although a foam tape material is preferred for the building water seal 22, alternative water seal materials and designs include elastomeric gaskets, o-rings, and c-rings, putty or other plastic materials in various shapes, lubricant coated seals, pressure actuated seals, and caulking.

The upper building or anchor space 24 has a volume sufficient to provide an air reservoir or cushion in the event of significant, but temporary air leakage past building air seal 28. The upper building air space 24 or air cushion tends to maintain air pressure close to the air pressure in the exterior environment E when air leakage occurs. Preferably, the air cushion volume per linear foot of the upper perimeter frame 19 is at least about 2.5 cu. in. per foot, more preferably at least about 6 cu in. per foot, but may be as small as about 1.0 cu. in. per foot. Other volumes are also possible depending upon the shape of the inner building space 21 and the size of the air opening 23, e.g., volumes may be minimal as long as an air opening or other passageway allows the pressure in the inner upper space 24 to substantially equalize with the air pressure in the exterior environment E under extreme conditions.

The top perimeter frame element 19 includes a first rain screen or baffle 31 and a second rain screen or baffle 27 that protrude downward into the outer air loop portion 21. The rain baffles 31 and 27, when combined with first and second upper rain screen or baffles 25 and 26 that are portions of an upper frame element 30, restrict water droplets in moisture-laden exterior air from entering the air hole 23 in any straight-line path. The circuitous path, as illustrated by arrow AP, from the exterior environment E to the air hole 23 tends to throw droplets of moisture outward from each turn of the air path AP .

The first and second rain baffles 31 and 27 are preferably spaced apart by baffle separation distance SD. Separation distance SD and a comparable distance between the 1st and 2nd upper rain screens or baffles 25 and 26 are preferably at least about 1/2 inch, but are more typically at least about 3/4 inch, and may be as little as about 1/4 inch or less. Other configurations and/or baffle shapes may have more or less baffles and/or separation distances SD, but baffles should preclude a straight-line path between the exterior environment E and air hole 23. First and second rain baffles 31 and 27 and first and second upper rain screen or baffles 25 and 26 preferably protrude into the outer air loop portion 21 a depth of at least about 3/8 inch, more preferably at least about 1/2 inch, but can protrude as little as about 1/4 inch or less.

Although the preferred shape of the second rain baffle 27 is L-shaped as shown in Figure 2 in order to, among other things, decrease the turning radius of the air path between rain baffles 31 and 27, a straight or I- shaped second rain baffle is an alternative shape. And although many other different baffle and protrusion shapes and depths are possible, the shape and depth of each baffle and protrusion should prevent a straight-line path of air from the exterior environment E from reaching air hole 23.

The top perimeter frame element 19 includes the rain screens or baffles 27 and 31 protruding generally downward and the upper panel frame element 30 includes upper rain screens 25 26 protruding generally upward, but the first upper rain screen 26 preferably has a portion located generally in between the first and second rain screens 31 and 27. The first and second upper rain screens 25 and 26 also protrude into the outer air loop 21, forming the edge of the first drainage gutter space 50. Although an offset and hooked shape for the first upper rain screen 26 as shown is preferred as well as a shape protruding into outer air loop portion 21 deeper than the second upper rain screen 25, many other shapes and protruding depths are possible. The second upper rain screen or element 25 and the third upper protrusion 25c are also used to form the edges of the second drainage gutter space 50a. The top perimeter frame element 19 is preferably attached to an upper panel frame element 30 using a frame attaching screw or other fastener 34. Similar to building screw or fastener 18, no seal is required at the fastener/screw passageways in top perimeter element 19 and upper panel frame element 30. Although a threaded frame fastener 34 is preferred, a variety of other means for fastening the frame elements are possible in alternative embodiments, e.g., the alternative attachment means or means for fastening the top perimeter frame 19 to the building 13 discussed above .

The upper panel frame element 30 is typically shop assembled to the window panel 11 and sealed at the exterior sealant line using window water seal 32 and window air seal 33. The window water seal 32 as shown in Figure 2 ^"is preferably a flat sealing tape such as a Norton Tape, but many other seal types, materials, or means for sealing can be used, e.g., elastomeric gaskets, o-rings, and c-rings; putty or other plastic materials in various shapes, lubricant coated seals, pressure actuated seals, etc.

The window air seal 33 is preferably a pre-formed wedge gasket. The preferred window air seal 33 is composed of EPDM, but many other seal types or means for sealing similar to the alternatives for the window water seal discussed above can be used. The window air seal 33 seals the interior sealant line near the edge of the window 11 between the window and glazing stop element 41.

Although many frame elements, such as upper panel frame element 30, are preferably aluminum extrusions, alternative frame segments may also be fabricated using different fabricating means and/or composed of other materials . ^' Other fabrication means and/or other materials of construction can include other metals and metal extrusions, castings, machined parts, elastomerics, injection molded plastics, and composites.

The cover frame element 35 is preferably an aluminum extrusion similar to other portions of the upper frame assembly 12 and is preferably attached to the upper panel frame element 30 by a second threaded frame screw or other fastener 34a positioned to allow sealing of cover air seal 38 with mating flanges 36 and 37 of the top perimeter frame 19 and upper panel frame 30. However, other means for attaching the cover frame element 35 to the upper window frame element 30 and/or perimeter frame element 19 may be used in alternative embodiments, such as adhesives, welding, clips, clamps, and t-slots. The glazing stop element 41 attaches to the upper panel frame 30 and provides a support for the window air seal 33. Although a clip-on attachment of the glazing stop element 41 to the upper panel frame 30 is preferred, alternative attachment means can be used similar to the alternative attachment means previously discussed. An optional interior air seal 46a, preferably composed of silicone caulking, may also be provided to minimize air transmission or leakage to or from the interior space IS. However, the clip-on attachment means, especially when combined with relatively smooth and/or less brittle materials of construction at a clip- on mating surface plus a tolerance for imperfect seals, may avoid the need for a separate air seal element since the assembly is tolerant of less-than-perfect seal. Other compositions and shapes may also be used for separate seals to replace the interior air seal 46a.

The upper panel frame element 30, top perimeter frame 19, glazing stop element 41, and the cover frame element 35 combine to form subassemblies having multiple air spaces or air loop portions, e.g., a cover space 39 inboard of cover frame element 35. These spaces serve several purposes. For example, a window air space 20 substantially around one end of window 11 provides a spaced-apart distance SP from the end of window 11 and seal mating surfaces of the upper panel frame 30 to the opposing portion OP of the upper panel frame element 30. The spaced-apart distance SP and slidable window seals 23 and 33 allow the window pane 11 to be displaced upward. The spaced-apart distance SP is preferably at least about 3/8 inch, more preferably at least about 1/2 inch, and most preferably at least about 3/4 inch, but is typically less than about 1 inch. The interconnected window air spaces 20, 20a (e.g., see Figure 3), and 20b (e.g., see Figure 4) also serve to form an inner air loop around the window water seal 32 that is pressure equalized with the exterior environment E .

As shown in Figure 2, the access to the head of the second frame screw 34a is preferably covered by optional cover plate 40 clipped onto the cover frame element 35. The clip-on plate cover 40 is optional, e.g., if aesthetic or other requirements indicate that inside facing screw heads to be covered.

The multiple attaching means, e.g., screws 18, 34, and 34a, attach the various frame elements to each other and to the concrete or other building portion 13. The attached building and frame elements form multiple air loops having multiple uses. The preferred inner and outer air loops and attachment of the upper perimeter frame segment 19 and upper panel frame element 30 having a spaced-apart distance SP within an air loop portion 20 allow easy installation and removal. The lack of a pressure differential across the threaded fasteners also minimizes water leakage into the building interior space IS and any attendant corrosion problems. Although the preferred embodiment does not include a seal for threaded fastener 34a since the enclosed design presents little risk of unacceptable air leakage, a seal with the threaded fastener may be included in alternative embodiments .

Another benefit of the preferred air loops and attachment means is when the cover frame element 35, if present, is detached from inside the building IS, the frame attaching screw 34 is easily accessed also from inside the building for removal, maintenance or repair/replacement of a panel. Initial installation of the anchor screws 18 securing the assembly to the building prior to installing the other removable components is also simplified, allowing the window system 10 to be substantially erected and maintained from inside the building without scaffolding.

Another advantage of the air loop and the slidable or motion-accepting sealing means is that installation time is dramatically reduced when compared to some other window installation methods, e.g., methods that require field labor to apply putty to seal the window or window installation from the exterior of the building. In addition to added installation time, the field installation is susceptible to dirt and other foreign materials causing imperfect sealing.

Still another advantage of the enhanced window frame assembly is the substantial elimination of water leakage from the exterior environment E to the interior space IS of the building. By providing an air hole 23 and/or other passageways for rain-screened exterior air to equalize the pressure on both sides of a water or outer seal, a spaced-apart inner air seal within an inner air space or air loop allows water leakage to be substantially eliminated even if a water seal is imperfect . Still another advantage of the enhanced window assembly is one or more optional thermal breaks 29 that may be- included in the various frame elements . The thermal breaks 29 are preferably composed of materials with adequate structural strength and relatively low thermal conductivity, such as urethane, PVC, or other semi-rigid plastics. The thermal breaks reduce heat transfer into or out of the interior space IS which may reduce condensation and associated corrosion and other water problems. Figure 3 shows a vertical frame assembly or joint

14a between a window panel 11 and vertical portion of a building 13a. Vertical window water seal 32a and vertical window air seal 33a are similar in design and function to the window water seal 32 and the window air seal 33 shown in Figure 2. The design and functions of many other items shown are also similar in design and function to comparable items shown in Figure 2, e.g., vertical cover 40a, vertical thermal breaks 29a, vertical building water seal 22a, vertical building air seal 28a, vertical glazing stop element 41a (shown without optional mating interior air seal) , vertical rain screens and baffles 25a, 26a, 27a, and 31a, vertical building fastener 18a, vertical air opening 23a, cover air seal 38 and the air loop portions such as the vertical inner air loop portion 20a.

The vertical anchor or perimeter frame element 19a shown in Figure 3 may be similar to the top perimeter element 19 shown in Figure 2, but an alternative design allowing slidable window attachment is shown and preferred. The vertical perimeter frame element 19a is not threadably attached to a vertical window frame element 30a (as is the perimeter frame element 19 to the upper panel frame element 30) , but is mated to a vertical joint spline frame element 42. The vertical joint spline frame element 42 includes a retaining ledge 43 for retaining a water seal 44. The multiple and opposing mating surfaces/seals between the vertical spline frame element 42 and the vertical perimeter frame element 19a at frame extensions 45 and 46slidably secures the protrusion frame element to the vertical perimeter frame element. The secured vertical joint spline or protrusion frame element 42 provides opposing mating surface/seal support for the vertical panel frame element 30a (which may also be secured to the upper panel frame element 30 at a mitered corner of the enhanced window assembly 10) at panel frame extensions 47 and 48. The slidable securing of the window assembly 10 preferably allows the windowpane 11 to be easily removed

(with access only from the interior space IS) without fully removing all other elements of the enhanced window assembly. This is in part achieved by having a clearance distance C between the upper vertical perimeter frame 19a (including frame extensions) and portions of the vertical joint spline or protrusion element 42. The preferred clearance distance C is at least about 1/8 inches, more preferably at least about 1/4 inches, but may be as little as 1/16 inches or even less. In order to obtain the clearance distance C, the protrusion or spline half- width PW of the vertical joint spline element 42 is preferably at least about 3/4 inches, more preferably at least about 1 inch, but may be as little as about 1/2 inches or less . The clearance distances and placement of vertical baffles/protrusions/rain screens to remove a majority of the water droplets from moisture-laden air is similar to the clearance distances and placement of rain screens or baffles shown on Figure 2.

Figure 4 shows a cross-sectional view of a bottom frame assembly and joint 16 between a window panel 11 and ^a window ledge or other portion 13b of the building. Again, many of the items in Figure 4 are similar in design and function to comparable items shown in Figures 2 & 3 and frame elements may be joined to comparable vertical items at mitered ends to form air loops and baffled air entry paths, e.g., bottom window water and air seals 32b and 33b, bottom thermal breaks 29b, bottom air passageway 23b, bottom building water seal 22b, bottom building air seal 28b, bottom glazing stop element 41b, bottom interior air seal 46b, bottom building screw 18b, and bottom rain shields and screens 25b, 26b, 27b, and 31b. However, some additional functions for these items may also be present, e.g., bottom air hole 23b may also serve to drain any water seeped into the lower inner air loop portion 20b and connect the inner air loop portion 20b to the outer air loop portion 21b. Bottom air hole 23b may also be used as a passageway for the bottom building screw 18b.

The window setting blocks 47 provide a support for the weight of windowpane 11. The support height SH is typically similar to the spaced apart distance SP shown in Figure 2. The window pane support 47 is preferably composed of EPDM, but alternative semi-rigid materials such as PVC may be used.

The bottom perimeter frame element 19b is secured to the building portion 13b somewhat similar to the attachment of top perimeter frame element 19, but the lower or bottom building screw or fastener 18b is located further away (or more remote) from the exterior environment E as is the lower or bottom building water seal 22b. This more remote location of lower building water seal further limits water access from the exterior environment E to the lower building screw 18b or bottom building air seal 28b. It also allows drainage holes 48 to drain separated water into the drainage space 49, which then drains separated water back to the exterior environment E. In alternative embodiments of the enhanced window assembly 10, bottom baffles may also be provided within or near the drainage space 49 to minimize water droplets in the exterior environment E from entering the drain holes 48.

Opening OD is sufficiently large to allow water drainage, but not so large as to allow excessive amounts of exterior water droplets to enter the opening. Opening OD is typically no greater than about 1/4 inches wide, more typically less than about 3/16 inches wide, but may be as large as about 1/2 inches or more.

The bottom panel frame element 30b is supported by and retained by the bottom perimeter frame member 19b _. at interfacing flange 52 and interfacing slotted flange

51. Interfacing flanges 51 and 52 also provide sealing surfaces for lower air seal 53. In alternative embodiments, the bottom panel frame element 30b can be attached to the bottom perimeter frame member 19b by various means including threaded connectors, clamps, and 0 clips.

Figure 5 shows a vertical frame assembly or joint 15 between two window panels 11a and lib, said window panels being generally horizontally adjacent and similar to the window panel 11 shown in Figure 2. Vertical 5 window water seals 32a and vertical window air seals 33a are preferably similar to the vertical water and air seals 32a and 33a shown in Figure 3 and are preferably connected to the upper horizontal water and air seals 32 and 33 at mitered corners. The left vertical frame 30c (looking inwardly towards the interior space IS) and right vertical frame 30a are preferably identical or mirror images of each other, composed of aluminum extrusions similar to the frame members shown in Figure 2, however other alternative frame materials and shapes can be used as discussed above. Most all other items shown in Figure 5 are similar, identical, or mirror images of the corresponding items shown in Figures 2 & 3 , e.g., the vertical joint spline member 42 and clip-on cover 40a. Similar to the vertical spaces 20a and 30a shown in Figure 3 , the vertical spaces shown in Figure 5 (e.g., outward vertical space 21a) are also at the same pressure as the exterior environment E because of one or more passageways or air holes (such as port 23 shown in Figure 2) fluidly connecting the vertical spaces to the exterior environment E. In an alternative embodiment, additional air holes or ports may also be provided in the vertical frame elements.

Figure 5 shows the vertical air spaces 20a formed by the frame members 30a and 30σ that provide spaced- apart distances SP1 and SP2 between the edges of the window panels 11a and lib and the frame members. The spaced-apart distances SP1 and SP2 are preferably similar and are at least about 3/8 inch, but more typically are at least about 1/2 inch and less than about 1 inch, but other spaced-apart distances are also possible.

The vertical panel frames 30a and 30σ are slidably sealed by vertical joint spline 42. However, other sealing means are also possible.

In the preferred embodiment shown in Figure 5 , the outer ledge 54 (i.e., furthest away from the building interior IS) acts as a rain baffle or rain shield/screen forcing any air entering at this point to take a circuitous route as shown by arrow AE . Since the cavity 20a is fluidly connected to the outside environment E (preferably by connections with one or more air loop portions 20shown in Figure 2) , there is essentially little or no pressure difference across the protrusion rain seal 44, which essentially precludes water from penetrating past the protrusion rain seal even if the protrusion rain seal is imperfect . A protrusion air seal 38a restricts air within an inner air loop portion 55 from entering the interior space IS of the building. The enhanced window frame assembly has still other advantages, e.g., it can be installed in the rain without substantially reducing the capability of the installed assembly to restrict air and/or water transfer between the building interior and exterior environments . Previous window assemblies require relatively dry conditions for installation, e.g., to apply caulking and to avoid trapping moisture in spaces where it is not desirable. In contrast, the preferred embodiment of the enhanced window frame assembly 10 does not require caulking, field water seal locations are substantially within airloops/frames and field installation work is minimized, rain screens are located between water seals and the exterior environment, and drainage paths are provided to direct stray water away from air seals.

Another advantage of the enhanced window assembly is that it also allows retrofitting to replace leaking or otherwise unacceptable existing windows or window assemblies with minimal cost, e.g., with installation access only from within the interior of the building. For example, a transition element can be used to replace the vertical joint spline element 42, wherein the transition element can be designed with one side similar to the interfaces shown on Figure 5 and the other side similar to the existing window frame interfaces.

Another advantage of the enhanced window assembly is that the one or more air holes or openings (e.g., air opening 23) serve a primary purpose of air entry allowing pressure equalization of the air loops with the exterior environment, but pressure equalized air loops and opening (s) may also serve other purposes. The air opening or openings (e.g., 23) are typically sized to allow a flow of air into the inner air loop such that pressure within the inner air loop is substantially equal to the air pressure of the exterior or building external environment E under extreme conditions, e.g., simultaneously handling water drain and air entry. In other words, the air openings are typically sized such that a "worst case" flow of air and water through the air openings will not cause a significant pressure drop across the air openings and within the air loop, e.g., a maximum pressure drop across the air openings of about 0.1 inches of water, more typically less than 0.05 inches of water, and preferably even less than 0.03 inches of water under worst case flows of air in and water out .

A worst case flow of air into the inner air loop through an air opening (e.g., opening 23) is typically caused by a combination of environmental, design, and sealing factors, the most important of which is typically air leakage past one or more imperfect air seals. The most likely area of seal imperfection is at the mitered corners of the air seal and various estimates (or actual test data) can be used to approximate air leakage at the air seal/panel assembly corners under various conditions of differential pressure across an imperfect air seal . As an option to further reduce air infiltration, an auxiliary seal such as caulking can be added to the area close to the field formed air seals.

Besides imperfect air seals at mitered ends, other factors that may cause air inflow into the inner air loop include water (possibly including condensation) draining out on the inner air loop, other seal imperfections, rapidly increasing barometric pressure in the exterior environment, and rapid thermal expansion of the inner air loop. As an example of sizing a single air opening 23, auxiliary and/or air seal ends or imperfections at the four mitered end joints can be estimated to each be the equivalent of circular openings about 5 square millimeters and that air leakage past these seal imperfections or corners is the major cause of air entering or leaving the air openings 23. In order to minimize any pressure drop across the air openings, one method is to size the air openings at least about 20 times as large as the equivalent seal imperfections, or having at least about 100 square millimeters or one air opening preferably having a diameter of at least about 3/8 inch, more preferably having a diameter of at least about 1/2 inch. In order to provide for other air flow factors, water drainage, and to further assure that pressure is safely equalized within the inner air loop, the most preferred embodiment includes three air openings 23 having a diameter of at least about 3/8-inch. Another purpose of at least one of the air openings (e.g., 23) is to allow rain or other water to drain out of (perhaps concurrently with air entering) the inner air loop, at least one of the air openings (e.g., opening 23b) should be in the lower frame segment 30b as shown in Figure 4 and be at least about 1/8 inch in diameter (or have a total cross-sectional open area of at least about 0.01 square inch) , preferably at least about 1/4 inch in diameter or have a total cross-sectional open area at least about 0.05 square inch. However, the preferred location of at least one air opening 23b is near the center of the lower frame segment 30b to provide for the primary air flow purpose, e.g., away from the vertical joint. Other air openings can be provided in other frame segments or locations to further assure that air pressure within the inner air loop is substantially equal to pressure in the exterior environment E. In an alternative embodiment, one or more of the portions of the inner air loop may be discontinuous (e.g., for lower building edge panels) and additional air openings (e.g., located near the lower portion of the side segments of the inner air loop) may be needed for air entry and/or to drain water from the inner air loop. In an alternative embodiment, at least two of the air holes are located in the lower frame segment 30b near each mitered corner of the panel. This dual corner location of air openings 23b allows water to easily drain from at least one air opening 23b at one end and air to enter the other air opening 23b. Putting a preferred third air opening 23b between the dual corner located air openings in lower frame segment 30b or on another lower frame segment allows water to easily drain from both ends (e.g., water entering from imperfect water seals in the side or vertical segments) and sufficient air flow to enter through the third or middle air opening -23b to substantially equalize the air pressure within the inner air loop to about the air pressure in the exterior environment E . Although in the preferred embodiment, air from the exterior environment E is forced around rain screens, rain shields or other baffles in a tortuous path that separates water such as rain from any air entering the air opening (s) such as 23, the significant size and location of the air opening (s) provides additional advantages. The upper rain screen member 25 and other baffles and protrusions not only form alternating path baffles that preclude a straight path flow of air (with possibly entrained water) from the exterior environment E to the air openings 23, but the alternating path baffles provide surfaces on which entrained water or particulates tend to impact since the less dense air can change flow direction more easily around the baffles than the more dense water droplets and particulates which tend to be "thrown" outward onto the alternating path baffles and collect thereon. The baffle-collected water droplets tend to coalesce and drain outward (e.g., through toward drain openings 48) towards the exterior environment E, carrying particulates with the draining water. Although the L-shaped rain shield 27b is preferred at or near one of the air openings 23b as shown in Figure 4 and the L-shape tends to increase the circuitousness of the air path "API", the L-shape has other advantages. Portions of the L-shaped rain shield 27b that are spaced-apart from an air opening 23b may not be required or required to be L-shaped since little or no air is entering at a spaced-apart distance from the air opening. If only a portion of the rain shield 27b is present or L-shaped near the air opening 23 and the remainder (spaced apart from any air openings) is nonexistent or straight, draining water on the rain shield will tend to be diverted away from the air opening 23b, thereby further minimizing water/particulate re- entrainment problems. In the preferred embodiment, the portion of baffle protrusion 16b that is L-shaped extends at least 1/16 inch on either side of air opening 23 and alternating path baffles/protrusions are spaced apart by at least about 1/16 inch, more preferably at least about 1/8 inch, but preferably spaced-apart by no more than about 1/2 inch, and typically protrude into the first joint space 21 by at least about 1/4 inch, more preferably at least about 9/16 inch.

Many other baffle gutter shapes, spacings, and protruding lengths are possible in alternative embodiments. Increased baffle lengths, smaller spacing, and thicker shapes may be needed when even less water entering the air opening (s) is desired, but the opposite may be desired if lower costs and a closer approach to pressure equalization is desired. Although the preferred embodiment uses extruded aluminum for the exterior baffles, one or more of these components may also be composed of other materials, such as other metals, wire screen, porous materials, and elastomerics . Other materials may have advantages in the areas of increased retaining/draining of impacted water and reducing water/particulate re-entrainment problems.

The glazing stop elements (e.g., 41 and 41a) and covers (e.g., 40 and 40a) are preferably clipped to or otherwise removably attached to the enhanced window assembly 10 allowing easy installation and removal of the window (s) 11 of other elements, but the preferred clipped attachment also provides other benefits. One end of the cover (e.g., 40a) preferably abuts the building, serving as a motion stop in one slidable direction, and removal of the cap allows a greater range of sliding motion for the vertical joint spline member 42 during subsequent removal steps. The abutment of the cover (e.g., 40a) also makes it difficult to grab or accidentally hook onto the protrusion member and displace or slide it to a disengage position unless the cover is first removed. Although a clipped cover is the preferred, alternative embodiments can have covers with thicker edges (to locate the assembled vertical joint spline member 42 further away from the building and allow a greater motion of the joint spline toward the building when the cover is removed) , a cover having edge stand-offs, a cover attaching to the building or to the vertical joint spline members means of pinned connections, hooks and slots, adhesives, or fasteners.

Air openings (e.g., 23) in an alternative embodiment may have different locations, shapes, and sizes to provide other benefits, e.g., several openings primarily sized for air flow having a preferable diameter of at least about 3/8 inch plus a separate drain hole near a water path of about 1/4 inch in diameter or less near a mitered corner to minimize re-entrainment of draining water. Other alternative embodiments can include an air hole in most if not all frame segments, air opening slots instead of the circular air opening (s) shown, a screen or filter placed over the air opening to further minimize water entry, and additional baffles placed in or near an air opening or inside air loop segments to still further minimize water entry.

The rain or water seal 44 placed between extension 43 of the vertical joint spline member 42 and flanges 46 and 47 shown in Figure 3 is preferably attached to the extension 43 and preferably extends for the entire distance between the ends of the vertical frames. However, alternative placements and attachments of these elements are also possible. In the preferred embodiment, window water seals

(e.g., 32 and 32a) are closed cell foam sealing tapes such as Norton tapes available from Norton Performance Plastics, now Saint-Gobain Performance Plastics, located in Wayne, New Jersey. However, alternative embodiments can use other types of seals or water flow restrictors . The preferred window air seals (e.g., 33 and 33a) are wedge gasket seals typically composed of EPDM material. However, alternative embodiments can use other types of seals or airflow restrictors.

In the preferred embodiment, building water seals (e.g., 22 and 22a) and building air seals e.g., 28 and 28a) are closed cell foam sealing tapes, such as Norton tapes similar to window water seals 32 and 32a. ^' However, alternative embodiments can use other types of seals or flow restrictors.

As an option to improve thermal insulation performance of the inventive curtain wall system, one or more thermal breaks (e.g., thermal breaks 29) are shown in Figure 2. Although a low thermal conductivity, plastic material is preferred for the thermal breaks 29, other substantially rigid, semi-rigid, or flexible materials with sufficient structural strength and limited thermal conductivity can be used for the thermal breaks. In addition, the aluminum-plastic interfaces between the thermal breaks 29 and the frame elements can be roughened or coated to further reduce thermal conductivity from the exterior environment E to the interior space IS. The thermal breaks 29 are preferably manufactured or shop assembled into the frame elements using a pour-and- debridge process, but other manufacturing or assembly methods are also possible, including manual insertion.

The preferred process of erecting or installing windows in a building or building structure typically starts with unpacking shipped components. For the assembly shown in Figures 1-5, the perimeter frames 19, 19a, 19b, and other joint members (e.g., 35, 40, and 42) are typically shipped separately from the partially assembled or shop-framed window panel subassemblies . A preferred process requires five major steps to install an enhanced window assembly, e.g., first securing and corner sealing the perimeter frame members to the building

(e.g., using screw 18 to attach perimeter frame members

19 to building 13), secondly securing shop-framed window panels into position using one or more attaching screws 34, thirdly installing one or more vertical joint splines 42, fourthly installing air seal members (e.g., 35) and securing frames using fasteners (e.g., 34a), and fifthly clipping on covers, e.g., 40 and 40a. ϊ-ⁿ alternative embodiments, the same design principles can be applied to other curtain wall systems, e.g., to the hidden frame air loop systems disclosed in U.S. Patent No. 5,598,671. For example, air openings would be similarly sized and placed for the primary purpose of air entry and also for the purpose of water drainage .

As shown in Figures 1-5, a preferred embodiment can also achieve the following performance improvements: a. The invention simplifies the formation of continuous air loops, seals, and thermal breaks. Several essentially continuous air loops and nominally continuous seals can be easily formed by miter-matching similar vertical and horizontal frame elements. In addition, thermal breaks can also be miter-matched to maintain the continuity of the thermal break function. Although protruding portions of frame segments can have different functions (or little or no function) at different locations around the air loop, the similar structure for each segment simplifies fabrication, erection, sealing, and the formation of essentially continuous pressure equalized air loops around the panels. b. The invention allows improved resistance to positive and negative wind loads. In some prior art window frame systems, the primary structural resistance against a negative wind load was provided by one or more fasteners in tension, resulting in the possibility of fastener fatigue, failure, or loosening due to repeated cyclic negative and positive wind or other loads over time. The cyclic loads can also result in seal failures. The preferred embodiment of the invention provides a primary structural resistance to negative wind load using one or more fasteners (e.g., 18) in shear attaching a perimeter frame member to a portion of the building 13 and by the structural engagement of opposing flanges or protrusions of the perimeter frame to the panel frame elements . The mating surfaces at the building air and water seals (e.g., 22 and 28) combined with the distance between the building air and water seals serves as the lever arm to provide resistance to twisting or turning of the perimeter frame element, reducing structural fatigue problems on the building screw (e.g., 18) or other fastener. c. The primary function of the building screw or other fastener (e.g., 18) is now essentially limited to resisting wind loads and providing a compression load on building seals rather than supporting the weight of the panels and/or resisting thermal expansion/contraction and/or providing compression loading on other seals. This results in reduced structural fatigue problems (and possible fastener loosening) with improved long term sealing, structural, and thermal performance .

Although the preferred embodiment of the invention has been shown and described, and some alternative embodiments also shown and/or described, changes and modifications may be made thereto without departing from the invention. Accordingly, it is intended to embrace within the invention all such changes, modifications, and alternative embodiments as fall within the spirit and scope of the appended claims.

Claims

1 1. A window frame assembly for supporting a window pane

2 substantially in a fixed location wherein said window

3 frame assembly is attached to one or more building

4 surfaces, said window frame assembly comprising:

5 At least one window frame element sealably g connected to a surface of said window pane forming at 7 least one framed window subassembly; g a perimeter frame element fastened to a building g surface using a fastener and capable of being sealably

I o connected to at least one of said framed window

I subassemblies; and

12 ^a protrusion frame element slidably connected to

13 said at least one of said framed window subassemblies,

1 wherein a clearance dimension limits sliding

15 travel of said framed window subassembly which can be 1 g disconnected from said frame assembly without unfastening 1₇ said perimeter frame element from said building surface.

2. The window frame assembly of Claim 1 wherein said fastener is a screw and said clearance dimension is at least about 1/8 inch.

3. The window frame assembly of Claim 2 which also comprises a plurality of seals contacting said perimeter frame element and a building surface .

4. A panel frame assembly for supporting a panel from a

2 building surface, said panel frame assembly comprising:

3 at least one panel frame element sealably

4 connected to a surface of said panel, said panel frame

5 element and said panel forming a framed panel c subassembly; at least one spline element slidably connected to _o said framed panel subassembly; and _q a first perimeter frame element sealably attached

10 to said building using at least two seal elements, said first perimeter frame element having at least one air 11 passageway for substantially equalizing air pressure 12 proximate to either side of at least one of said seals, 13 wherein the total cross-sectional area of said air 14 passageway is at least about 0.01 square inch. 15

5. The panel frame assembly of Claim 4 which also comprises a second perimeter frame element sealably connected to said framed window subassembly and fastened to a building surface.

6. The panel frame assembly of Claim 5 which also comprises at least a first air space bounded at least in part by a surface of said building, at least one surface of each of said first and second perimeter frame elements, and at least a first of said seals, wherein said air space has a volume of at least about 1 cubic inch per linear foot of said perimeter frame elements.

7. The panel frame assembly of Claim 6 which also comprises a second air space bounded at least in part by at least one surface of each of said first and second perimeter frame elements and a second seal, said second air space fluidly connected to said first air space.

8. The panel frame assembly of Claim 6 which also comprises means for draining water from said first air space .

9. The panel frame assembly of Claim 8 which also comprises means for draining water from said second air space.

10. The panel frame assembly of Claim 4 which also comprises a window water seal and a window air seal contacting said panel, wherein said window water seal, said window air seal, said panel frame element and said window pane form at least in part the boundaries of a third air space.

11. The panel frame assembly of Claim 10 which also comprises means for draining water from said third air loop portion .

1 12. A window frame assembly for supporting a window pane

2 substantially in a fixed location wherein said window

3 frame assembly is attached to one or more building surfaces, said window frame assembly comprising:

5 at least one window frame element sealably g connected to a perimeter area of said window pane forming a framed window subassembly; g a first building frame element fastened to a g building surface using a fastener and sealably connected

10 to said window frame element ; 11 a second building frame element fastened to a ₁ building surface using a fastener and sealably connected

13 to said window frame element and attached to said first building frame element, wherein said building frame

14 elements form a substantially continuous frame assembly

15 around said window pane; and

16

₁₇ a protrusion element slidably connected to said

.₀ framed window subassembly and at least one of said I o

_{1 q} building frame elements ,

20 wherein one or more fasteners capable of

21 attaching one or more building frame elements to one or

22 more building surfaces through one or more fastener

23 openings in one or more building frame elements in the

24 absence of one or more seals restricting air passage

2 through a fastener opening that would otherwise provide a

26 potential path for exterior environment air to flow

27 towards a building interior space.

1 13. The window frame assembly of Claim 12 wherein said

2 fasteners openings are exposed to an air pressure on

3 either side of said fastener passageway that is

4 substantially equal to the exterior environment air

5 pressure .

1 14. A window assembly for a building comprising:

2 a window pane ;

3 a panel frame element sealably connected to said

4 window pane ; and

5 a perimeter frame having a seal connected to said 5 panel frame element for restricting air and water 7 transmission from an exterior environment into an g interior space within said building after said window g assembly is installed on said building,

10 wherein said seal is located such that it can be

11 installed when it is raining without significantly 2 reducing the capability of the window assembly to 3 restrict said air and water transmission.

15. A process for replacing an existing window assembly

2 on a building with an enhanced window assembly

3 comprising:

, removing said existing window assembly from said

5 building; g installing a transition frame element connected

7 to said building; 8 connecting an enhanced window pane and panel

9 frame subassembly to said transition frame element; and

I o connecting a perimeter frame to said building and

II to said panel frame subassembly.

16. A process for installing an enhanced panel assembly

2 to a building comprising:

3 attaching and corner sealing a plurality of

4 perimeter frame members to said building;

5 removably connecting a framed window panel g subassembly to said perimeter frame member;

7 connecting a joint spline member to a framed

0 window panel subassembly; and _g removably attaching a cover frame member to said

1_Q perimeter frame member.

17. The process of Claim 16 which also comprises

2 removably attaching a cover to said cover frame member.

1 18. The process of Claim 17 which also comprises

2 connecting a joint spline member to several framed window

3 panel subassemblies .