Method and Apparatus for Reducing Solar Radiation Absorption Through a Roof
Structures and methods use a high-albedo fabric to cover the surface of building roofs, thereby shielding the roof from solar radiation that would otherwise be absorbed into the roof as heat. The high-albedo fabric may be standard or a modified version of SunTex® 90% woven polyester-polyvinyl fabric. Produced in large sizes, the material may be placed on the roof similar to how wall-to-wall carpet is installed, with bonded seams and cutouts for the vents, stacks, and other roof structures. The high-albedo fabric may be adhered to the roof surface and attached the roof edges with fabric binding clips, thereby ensuring the fabric is resistant to wind damage. The high-albedo fabric may be printed with designs (e.g., shingle or roof tile patterns) that enable the fabric to be applied to existing structures without altering the aesthetic appearance of the roof.
This application claims priority to U.S. Provisional Application No. 61/295,393, filed Jan. 15, 2010.
FIELD OF THE INVENTIONThe present invention relates generally to roofing systems, and more particularly to methods, materials and apparatus for reducing the amount of solar energy absorbed by a roof.
BACKGROUNDThe high level of energy consumption by homes and buildings is an issue which has received considerable attention in the recent years due to concerns about the environment and rising energy costs. A building's roof absorbs a significant amount of solar radiation in the form of heat, much of which is transferred to the underlying structure by conduction. High levels of heat absorption through a roof ultimately elevate the amount of energy required to air-condition the indoor space to a cool temperature, especially in areas with consistently strong sunlight exposure throughout the year. Shingles made of asphalt or made of asphalt-mixtures are frequently used in current residential roofing systems because of their durability, waterproofing function characteristics, and relatively low cost. However, most of the materials used to make shingles and other protective roof membranes, including asphalt, tend to absorb solar energy.
SUMMARYThe various embodiments and methods provide economical shielding for roofs that reflects a large amount of solar energy by covering the roof with a high-albedo fabric, thereby reducing the thermal load on the building. The various embodiments may be implemented on existing structures by cutting openings in the fabric to accommodate existing roof fixtures, enabling installation without changing the shingles, decking, and/or other roof materials, and without altering the aesthetic appearance of the roof. In addition to reducing energy consumption on cooling, the various embodiments may enable the construction of roofs with greater wind resistance by providing an effectively smooth surface on the roof, eliminating potential lift of the individual shingles at their exposed edges and by decreasing the amount of soffit vent area necessary to keep the roof properly ventilated.
The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate exemplary aspects of the invention. Together with the general description given above and the detailed description given below, the drawings serve to explain features of the invention.
The various aspects will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References made to particular examples and implementations are for illustrative purposes and are not intended to limit the scope of the invention or the claims.
The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.
The term “eave” is used herein consistent with its customary meaning in the building industry to refer the lower portion of a sloping roof which projects beyond the exterior side wall of a structure, i.e., the gap between a structure's siding and the roofline. The term “soffit” is used herein consistent with its customary meaning in the building industry to refer to any structure that forms an enclosing surface from top of an exterior side wall to the outer edge of a roof. The term “facia board” is used herein consistent with its customary meaning in the building industry to refer a structure which forms the end of a roof support element (e.g., rafter or truss) and/or decking on the exterior of a roof. A fascia board may run, for example, perpendicular to a horizontal soffit or may run perpendicular to the slope of the rafters and decking.
As used herein, the terms “decking” and “deck” refer to the under-support layer of a roof which is between the primary structural components (e.g., trusses and joists) and the weatherproofing layer (e.g., shingles, tiles, etc.). The decking may be made from a variety of materials, including, but not limited to, plywood sheathing, wood tongue and groove, corrugated metal, encapsulated polystyrene, and reinforced concrete.
The various embodiments are illustrated in the drawings and described herein with reference to a roofing system with a weatherproofing layer built with shingles, which is merely one example of a roof construction that may benefit from the various embodiments. The following descriptions and the figures are not intended to limit the scope of the claims to any particular structure, design or construction.
A roof is generally formed by fastening a sheet of decking material, such as wood plank or metal, to the top of the structural components.
The materials used to make shingles and roof tiles, which are efficient in sheltering a roof from water and weather, tend to absorb radiation from the Sun in the form of heat and conduct such heat to the interior of the building. Thermal energy from the roof structure conducted into the structure can result in hot air in the inner spaces of the roof, especially in the attic area, which adds to the thermal load on air conditioning systems. Thus, solar energy absorbed by the weatherproof roofing system used on a home can drive up the costs to air condition the home.
Sloping roofs are typically designed with one or many vents to allow breathing and air flow for the underlying attic space. Soffit vents 116, either multiple individual or a single continuous vent, are commonly installed to complement existing roof vents 102a, 102b placed at a higher point. Current roof ventilation systems lower temperature through convection, with soffit vents working as inlets of ambient temperature air from outside. Where there are existing high vents on a roof, hot attic air rises and exhausts through the vents at the upper portion of the roof, creating a pressure differential in the attic that causes cooler air to be pulled in through installed soffit vents 116. This current design is thermally inefficient, even when aided by ventilation fans that take suction from the attic and exhaust to the exterior of the house.
In strong winds, soffit vents 116 may contribute to roof destabilization, which increases the risk of roof damage or loss due to high wind conditions caused by hurricanes and tornadoes. Even a slight degree of roof damage may provide a point at which moisture can enter a home and cause mildew growth and waterlogged insulation, both of which can cause ceiling collapse. Further, light and moderate winds still may cause snow melt and other outdoor moisture to enter an attic directly through a soffit vent 116. Thus, changes to roof systems that could eliminate the need for soffit vents would provide structural rigidity and service lifetime improvements, potentially enabling the soffit to be eliminated or closed off and allowing the attic space to be air conditioned as the conducted heat through the roof would be at or near the outdoor ambient temperature.
The various embodiment structures and methods deploy a high-albedo fabric onto the surface of roof structures, thereby shielding the roof from solar radiation that would otherwise be absorbed into the roof as heat. The high-albedo fabric, which may be standard or a modified version of SunTex® 80% or 90% woven polyester-polyvinyl fabric or an equivalent high-albedo material, reflects a large fraction of solar radiation (e.g., up to 80% for SunTex® 80% and up to 90% for SunTex® 90%), which provides the thermal shielding effect. By producing the high-albedo fabric in large width rolls, the material may be placed on the roof similar to how wall-to-wall carpet is installed, with bonded seams and cutouts for the vents, stacks, and other roof structures. The high-albedo fabric may be glued, tarred or otherwise bonded to the roof surface, and edge binding structures may be used to secure the fabric to the edge of the roof, such as along eaves and soffits, thereby ensuring the fabric is resistant to wind damage. The various embodiments may be implemented on existing roofs without changing the shingles, decking, or other materials that make up the roof. Further, the high-albedo fabric may be printed with designs (e.g., shingle or roof tile patterns) that enable the fabric to be applied to existing structures without altering the aesthetic appearance of the roof. By reducing the thermal energy absorbed into the roof, the various embodiments provide significant energy savings without requiring significant structural changes to the roof. Further, the reduced heat load from the roof may enable the elimination of many, if not all, soffit vents, thereby reducing the vulnerability of a roof to high winds.
In an embodiment, the roof shield is constructed out of SunTex® 90% woven polyester-polyvinyl fabric material which is made by Phifer Incorporated of Tuscaloosa Ala. The technical characteristics of SunTex® 90% are as follows:
In a further embodiment, the yarn diameter and weave density is increased in order to reduce the fabric pore size, which may improve the thermal properties of the material over long-term exposure on the roof surface. For ease of description, “SunTex” is used herein to refer to SunTex® 80% and/or 90% and derivatives of that material. SunTex is used to illustrate the various embodiments of the present invention, but is not intended to limit the subject matter recited in the claims except as specifically recited.
Previous efforts to minimize the absorption of solar radiation by rooftops has focused on using light color building materials, such as white asphalt shingles instead of dark ones. Such products, however, only reflect a small portion of solar radiation, typically limited to that within the visible light spectrum (i.e., with wavelengths (λ) from 400-700 nm). However, such materials still absorbed most of the thermal portion of the solar radiation. Approximately 44 percent of the solar radiation reaching the earth is in the visible spectrum, while seven percent is in the ultraviolet spectrum (λ=10-400 nm), and 49 percent is in the infrared spectrum (λ=700-300,000 nm). Thus, half of the energy falling on the roof is thermal energy conveyed in the infrared spectrum.
The various embodiments reduce the thermal loading on roofs by reflecting much of the sun's thermal radiation with a fabric that exhibits a high albedo in the infrared spectrum. As illustrated in
As illustrated in
In order to ensure that wind cannot lift the edge of the windshield fabric along the edges of the roof, a fabric clamping structure may be applied to firmly fix the fabric to the eaves.
The fabric edge clamp 502 illustrated in
The edge clamps described in
As illustrated in
It should be appreciated that the steps in method 700 may be performed in an order different from that shown in
In a further embodiment, the high-albedo fabric used to form the roof shield may be printed during or after the weaving process used to manufacture the fabric to include a design, image, colors, letters, or other artistic features. For example, the fabric may be imprinted with a design resembling shingles or roof tiles so that when viewed from a distance it is not obvious that a fabric covering the roof. Such printed patterns are not limited to mimicking normal route structures, and may encompass and design that a homeowner may desire. For example, the fabric could be imprinted with the logo of a favorite football team, the name or logo of university, an advertisement, and abstract art designs. Further, the fabric may be dyed to a wide range of colors, enabling homeowners to color their roofs by applying the desired color roof shield.
The embodiments described above may be implemented on any of a variety of roof types, including, but not limited to, cross-gabled, hipped, mansard, flat, or shed roofs. The foregoing method descriptions and process diagram are provided merely as illustrative examples and are not intended to require or imply that the processes of the various embodiments must be performed in the order presented. Skilled artisans may implement the described functionality in varying ways for each particular roofing system, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. Words such as “thereafter,” “then,” “next,” etc. are not intended to limit the order of the processes; these words are simply used to guide the reader through the description of the methods. Further, any reference to claim elements in the singular, for example, using the articles “a,” “an” or “the” is not to be construed as limiting the element to the singular.
The foregoing description of the various embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, and instead the claims should be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for implementing a roof shield on top of a roof's surface, comprising:
- measuring dimensions of the roof's surface;
- cutting pieces of a high-albedo fabric to match the dimensions of the roof's surface;
- applying the high-albedo fabric to the roof's surface;
- heat-sealing edges of the high-albedo fabric pieces together as necessary to form one contiguous fabric over the entire roof's surface; and
- securing exterior edges of the high-albedo fabric in a fabric edge clamp attached to the edges of the roof.
2. The method of claim 1, wherein the high-albedo fabric is SunTex 90% material.
3. The method of claim 1, wherein the high-albedo fabric is SunTex 90% material with an increased weave density.
4. The method of claim 1, further comprising cutting the high-albedo fabric to provide a close fit around fixtures and protrusions on the roof's surface.
5. The method of claim 1, further comprising applying an adhesive to the roof's surface before applying the high-albedo fabric to the roof's surface.
6. The method of claim 5, wherein the adhesive comprises tar.
7. The method of claim 1, wherein the fabric edge clamp is secured with a plurality of fasteners to one of an edge surface of the roof, a fascia board, and a soffit.
8. The method of claim 7, wherein the fabric edge clamp comprises a first strip of rigid material and a second strip of rigid material, wherein the high-albedo fabric is positioned between the first and second strips of rigid material, and a clamping pressure is applied to the high-albedo fabric by the plurality of fasteners.
9. The method of claim 7, wherein the fabric edge clamp comprises a first strip of rigid material and a second strip of rigid material, wherein the high-albedo fabric is positioned between the first and second strips of rigid material, and a clamping pressure is applied to the high-albedo fabric by a plurality strip-to-strip fasteners prior to fastening the fabric edge clamp to one of an edge surface of the roof, a fascia board, and a soffit.
10. The method of one of claims 8 and 9, wherein the high-albedo fabric is further attached to the fabric edge clamp by an adhesive.
11. The method of claim 1, wherein securing exterior edges of the high-albedo fabric in a fabric edge clamp attached to the edges of the roof comprises:
- overlaying a rigid strip over the exterior edges of the high-albedo fabric and an edge of the roof; and
- securing the rigid strip to the edge of the roof with a fastener.
12. The method of claim 11, further comprising applying an adhesive to one of the rigid strip, the exterior edge of the high-albedo fabric, and the edge of the roof prior to securing the rigid strip to the edge of the roof.
13. A roof shield, comprising:
- a piece of high-albedo fabric cut to fit dimensions of a roof with openings provided to match locations of fixtures and protrusions of the roof; and
- a fabric edge clamp coupled to exterior edges of the high-albedo fabric, the fabric edge clamp configured to securely attach the high-albedo fabric to an edge structure of the roof.
14. The roof shield of claim 13, wherein the piece of high-albedo fabric comprises multiple smaller pieces heat-sealed together along edges.
15. The roof shield of claim 13, wherein the high-albedo fabric comprises SunTex 90%.
16. The roof shield of claim 13, wherein the high-albedo fabric comprises SunTex 90% with increased weave density.
17. The roof shield of claim 13, wherein the high-albedo fabric comprises a three layer structure, comprising:
- a first layer of SunTex 90%;
- a second layer comprising an adhesive coupled to the first layer; and
- a third layer comprising a removable non-adhesive material configured to protect the second layer from contacting other materials and to be stripped off when the high-albedo fabric is applied to the roof.
18. The roof shield of claim 13, wherein the fabric edge clamp comprises a first strip of rigid material and a second strip of rigid material, wherein the high-albedo fabric is positioned between the first and second strips of rigid material, and wherein a clamping pressure is applied to the high-albedo fabric by a plurality of fasteners used to attach the fabric edge clamp to the roof.
19. The roof shield of claim 13, wherein the fabric edge clamp comprises a first strip of rigid material and a second strip of rigid material, wherein the high-albedo fabric is positioned between the first and second strips of rigid material, and wherein a clamping pressure is applied to the high-albedo fabric by a plurality of strip-to-strip fasteners.
20. The roof shield of claim 19, wherein the fabric edge clamp further comprises an adhesive coupling the high-albedo fabric to one or both of the first and second strips of rigid material.
Type: Application
Filed: Dec 6, 2010
Publication Date: Jul 21, 2011
Applicant: SE2 International LLC (Sebastian, FL)
Inventor: Peter Kahle (Oregon, OH)
Application Number: 12/960,981
International Classification: E04B 1/78 (20060101); E04B 7/00 (20060101); E04D 5/14 (20060101); E04D 5/10 (20060101);