US20150259920A1

US20150259920A1 - Energy Efficient Shingles

Info

Publication number: US20150259920A1
Application number: US14/638,180
Authority: US
Inventors: Marwa Mohamed Hassan; Micah Joel Kiletico
Original assignee: Individual
Current assignee: Louisiana State University
Priority date: 2014-03-13
Filing date: 2015-03-04
Publication date: 2015-09-17

Abstract

A novel energy efficient shingle is disclosed. The shingle is layered with the top layer comprising recycled glass cullet coated with a reflecting material such as TiO₂. The novel shingle provides significant improvement in the Solar Reflectance Index (SRI).

Description

The present application claims the benefit of U.S. Provisional Patent Application No. 61/952,515, filed on 13 Mar. 2014, which is hereby incorporated by reference herein in its entirety including, but not limited to, those portions that specifically appear herein.
This invention pertains to novel energy efficient shingles.

BACKGROUND OF THE INVENTION

Significant sources of urban heating are heat islands, wherein roofs of buildings absorb heat and then dissipate absorbed heat into the buildings or into the atmosphere in the vicinity of the heat islands. For buildings with dark, non-reflective surfaces the problem is worse.
Heat islands may increase outdoor air temperature by about 2 to 8 degrees Fahrenheit within a specific area, or “island.”
Current single roofing technologies that are used to reduce building thermal loads and reduce “heat island” effects are based on a concept called “cool roofs.” A cool roof is designed to reflect solar heat flux instead of allowing the solar heat flux from penetrating through the roof into a building. Further, energy-efficient shingles should allow heat within a house to dissipate in the evenings when the sun is down.
There are three main methods for constructing solar reflecting roofs; (1) use of highly reflective material, for example, white polyvinyl coverings; (2) coating a roof with a highly reflective coating; and (3) the use of green roofs or living roofs, which is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane.
A highly reflective roof typically has a solar reflectance index (SRI) (ASTM E1980), (which is the best tool to measure heat reflectance as it incorporates both reflectance and emittance in a single value representing a materials temperature in the sun) of 78% or higher.
Conventional tar and gravel roofs typically have a SRI value of between 3% and 10% due to the non-reflective nature of these surfaces.
From this discussion, it is noted that none of the available techniques have produced energy efficient roofing that is affordable.

BRIEF DESCRIPTION OF INVENTION

The invention described herein is a novel cost-effective shingle that used recycled glass coated with a white pigment for the top layer of the shingle.
Waste glass, such as food and beverage containers, light bulbs, and broken glassware, may be obtained from construction and demolish waste sites (“C&D”). This waste glass is called “glass cullet.”
Typically, glass cullet obtained from a C&D facility contains glass particle that are too large. Thus, before use, the glass cullet was ground so that the particles were smaller than about 2.5 mm.
The invention described herein used recycled glass cullet as a top surface for asphalt-based shingles.
The glass cullet was coated with a white pigment before attaching to the top surface of the asphalt-based shingles to increase reflection of the shingles.
This invention also provided a new use for waste, broken glass. With the increases in energy costs and the gradual depletion of natural resources, there is a need to conserve energy and recycle waste. The United States Environmental Protection Agency estimates that about 11.5 to 12.8 million tons of glass waste is generated annually. Broken and crushed glass is plentiful and may be recycled into a new and useful product.
Glass cullet was isolated by color, including green and clear.
The novel shingles disclosed herein were effective at reflecting sunlight and thus will be effective at reducing heat islands in urban areas.
The novel energy efficient shingles disclosed comprise three layers; an interior base mat layer with a bottom side and a top side, impregnated with an asphalt-filler material; a backdust layer on the bottom side of the asphalt-impregnated mat; and a reflective layer on the top side of the asphalt-impregnated mat.
The mat may be selected from a group containing organic felt and fiberglass.
The asphalt-filler material comprises air blown asphalt and recycled glass cullet, wherein the glass cullet was sized to be between about 45 μm and 150 μm.
The backdust layer comprises recycled glass cullet, wherein the glass cullet was sized to be between about 70 μm and 600 μm.
The reflective layer comprises recycled glass cullet, coated with a white pigment, whereas the coated glass cullet was sized to be between about 600 μm and 3.00 mm.
A white pigment was selected from the group of white pigments consisting of Sb₂O₃, BaSO₄, PbCO₃.Pb(OH)₂, TiO₂, and ZnO.
The bottom side layer of the novel shingle was placed in contact with the roof, and the top side layer of the novel shingle was faced to the atmosphere.
Recycled glass cullet collected from C&D processing plants was reduced in size by placing it in a high performance mixer. Fragments were sieved and separated by size.
The ground recycled glass was used in place of traditional materials in the manufacture of shingles, including calcium limestone.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1. A top view of a layered shingle with each layer shown in an exploded view.

FIG. 2. A side view of a layered shingle with each layer shown from the bottom to the top.

DETAILED DESCRIPTION OF THE INVENTION

The novel energy efficient shingles (50) disclosed comprise three layers as shown in FIG. 1; an interior base mat layer (30) with a bottom side and a top side, impregnated with an asphalt-filler material (20); a backdust layer (40) on the bottom side of the asphalt-impregnated mat; and a reflective layer (10) on the top side of the asphalt-impregnated mat. FIG. 2 shows the novel shingle viewed from the side. A bottom dustback layer (40) is beneath the asphalt-filler layer (20). Between the asphalt-filler layers (20), a matting layer (30) is shown. Above the matting layer (30) and the asphalt-filler layer (20) is a reflective layer (10).
Fiberglass matting (30), wherein the matting weight was 15-30 lb per 100 square foot area, was used as the base mat layer (30), wherein the mat was fully impregnated with an asphalt-filler mix (20). An asphalt-filler mix for conventional shingles was calcium carbonate mixed with air blown asphalt. The asphalt-filler layer (20) for the novel shingle comprised air blown asphalt and recycled glass cullet.
The asphalt-filler mix (20) for novel shingles had a ratio of air blown asphalt to glass cullet between about 30:60 to 40:70. The glass cullet used for the asphalt-filler mix (20) was sized to be between 45 μm and 150 μm.
The bottom backdust layer (40) was bound to the asphalt-filler mix (20) on the mat (30) wherein the surface of the bottom layer was covered with about 0.3 g/sq.in. to about 1.3 g/sq.in. of recycled glass cullet. The glass cullet used for backdust (40) was sized to be between about 75 μm to about 600 μm. The bottom layer was bonded to the mat by the asphalt-filler mixture (20). The overall thickness of the shingle (50) was about the same as the thickness of current asphalt shingles being used in the market.
For the top layer (10), a white pigment, for example, TiO₂, was coated onto the surface of recycled glass cullet. Between about 5% and 10% by weight TiO₂, and more preferably about 8% by weight TiO₂, was mixed with the glass cullet to prepare the top, reflective layer of the shingles. The mix of glass cullet and TiO₂was submerged under water for 2-5 minutes, after which the mixture dried at 110° C. to constant mass. Then the dried TiO₂coated glass cullet was added to the shingle's top surface. The coated glass cullet was added to the top of the shingle so that the top surface (10) of the asphalt-impregnated mat (30) contained about 1.5 g/sq.in. to about 2.5 g/sq.in. of the coated glass cullet. The glass cullet used for the top-reflective layer (10) was sized to be between about 600 μm to about 3.0 mm.
A novel shingle (50), when placed on a roof, would be oriented so that the top reflective layer (10) is the outer layer and the backdust layer (40) would be in contact with the roof.
The invention can be applied to all types of asphalt shingles including strip shingles, 3-tab asphalt shingles, and laminated asphalt shingles. It can also be extended to be used with other types of roofing systems including roll up asphalt roofs, single ply rubberized asphalt, Multi-ply (built-up) roof systems and Ballasted Roofs.
The invention may also use other type matting than fiberglass, including organic felt.

Example 1

Prototype Shingle

The filler mixture was prepared with air blown asphalt with a viscosity of 33,500 cP (centipoise) (the viscosity was measured at 135° C.). The air blown asphalt was heated to 204° C. to lower the viscosity and allow for better mixing with the recycled glass. The recycled glass (with size ranging from 53 μn to 75 μm) was heated to a 100° C. The recycled glass is added to the binder according to the measurements shown in Table 1 and mixed thoroughly. The viscosity of the mixture was measured at 204° C. and 150° C. and was found to be 20,000 cP and 33,940 cP. The mixture was placed back in the oven and heated to 230° C. For a sample of 3″×3″, 14.7 g air blown asphalt and 27.3 g recycled glass (35:65 ratio) was used for layer two.

TABLE 1

ANATOMY OF SHINGLE SAMPLE

	BY WEIGHT	PERCENT
	(Grams)	BY WEIGHT

Fiberglass Matting (3″ × 3″)	2.0	4%
Filler Mixture	36.0	68%
Asphalt (35%)	12.6	24%
Glass Cullet (65%)	23.4	44%
Top Surface Glass Cullet	13.0	24%
Backdust Glass Cullet	2.20	4%
Total Shingle Sample	53.2	100%

Several 3′×3″ fiberglass mats were placed into a hot metal mold. The filler mixture was then poured over the fiberglass mats to allow the filler mixture to impregnate the mats. The mold was then placed in an oven heated to 230° C. where it remained for 15-20 minutes to allow for full penetration of the filler mixture into the mats.
Top surface glass cullet sized between 0.814 mm to 2.83 mm were coated with TiO₂by submerging a mixture of TiO₂and glass cullet in water, thoroughly mixing and then heating the mixture to a 110° C. at which temperature to dry the mixture to constant mass.
TiO₂coated glass cullet was added to the top of the molten asphalt mixture that had been impregnated into the mats so that the top surface was completely covered with the TiO₂coated glass cullet. The mold was then cooled to room temperature.
Once cooled, the prototype shingles were removed from the mold.
The prototype shingles were turned so that the bottom side of the shingle was available. Heat was applied to surface of the bottom side of the shingle to melt the surface of the asphalt binder located on the bottom surface. Backdust made from glass cullet sized between about 75 μm and 600 μm then was added to the heated bottom surface. Then the prototype shingles were allowed to cool to room temperature.
Different types of glass cullet were used, including green glass and clear glass.

Example 2

Solar Reflectance Index (SRI)

SRI incorporates both solar reflectance and emittance into a single value and is a measure of the constructed surface's ability to stay cool in the sun by reflecting solar radiation and emitting thermal radiation. It is defined such that a standard black surface (initial solar reflectance 0.05, initial thermal emittance 0.90) has an initial SRI of 0, and a standard white surface (initial solar reflectance 0.80, initial thermal emittance 0.90) has an initial SRI of 100. Materials with the highest SRI values are the coolest choices for roofing.
Table 2 displays the SRI of conventional asphalt shingles.

TABLE 2

SOLAR REFLECTANCE INDEX OF CONVENTIONAL
ASPHALT SHINGLES

TYPE OF THE		TYPE OF THE
ASPHALT SHINGLE	SRI	ASPHALT SHINGLE	SRI

White	21	Black	1
Gray	4	Weathered Wood	4
Green	18	Dark Brown	4
Antique Silver	19	Beachwood Sand	19

Table 3 displays the SRI of the novel asphalt shingle.

TABLE 3

SOLAR REFLECTANCE INDEX OF NOVEL ASPHALT SHINGLES

Material Composition

ID	Top Surface	Filler	SRI

X1	Control 1: Ceramic Coated Granules	Limestone	0
X2	Control 2: Ceramic Coated Granules	Clear Glass 1	0
A	Green Glass	Limestone	3
B	Clear Glass 1	Limestone	5
C	Green Glass	Green Glass	3
D	Clear Glass 1	Clear Glass 1	5
C1	Green Glass & Pigments	Green Glass	28
D1	Clear Glass 1 & Pigments	Clear Glass 1	27
G1	Clear Glass 2 & Pigments	Clear Glass 2	30

As can be seen from a comparison of the SRI for the novel shingle and conventional shingles, the novel shingle will reflect more solar energy than those shingles currently available.

Claims

1. A roof covering comprising a substrate mat, an asphalt binder backdust, and white pigment coated glass cullet.

2. A roof covering according to claim 1 wherein the white pigment is selected from a group consisting of Sb₂O₃, BaSO₄, PbCO₃.Pb(OH)₂, TiO₂, and ZnO.

3. A roof covering according to claim 1 wherein the white pigment comprises TiO₂.

4. A roof covering according to claim 1 wherein the mat is selected from a group consisting of organic felt and fiberglass; wherein said mat has a density of between 0.15 and 0.30 pounds per square foot.

5. A roof covering according to claim 1, wherein the mat is fiberglass.

6. A roof covering according to claim 1 that is a plurality of shingles.

7. A shingle according to claim 6, wherein the shingle comprises:

a. A mat impregnated with an asphalt binder comprising air blown asphalt and glass cullet wherein the mat has a top side and a bottom side, and

b. wherein the top side of the mat is imbedded with TiO₂coated glass cullet, and

c. wherein the bottom side of the mat is imbedded with backdust comprising glass cullet; and

d. wherein the shingle is oriented so that the top side of the shingle faces the atmosphere and the bottom side of the shingle is placed against the roof.

8. An asphalt binder according to claim 7 wherein the air blown asphalt is between 30% and 40% by weight of the glass cullet.

9. An asphalt binder according to claim 8 wherein the glass cullet is sized between 35 μm to 200 μm.

10. A TiO₂coated glass cullet according to claim 7 wherein the TiO₂is between 7% and 11% by weight of the glass cullet.

11. A glass cullet according to claim 10 wherein the glass cullet is sized between 500 μm and 3.0 mm.

12. A glass cullet used for backdust according to claim 7 wherein the glass cullet is sized between 70 μm and 600 μm.

13. A shingle according to claim 7 wherein the surface of the bottom layer of the mat is covered with glass cullet at coverage of about 0.3 g/sq.in. to about 1.3 g/sq.in. of recycled glass cullet.

14. A shingle according to claim 7 wherein the surface of the top surface of the mat is covered with coated glass cullet at coverage of about 1.5 g/sq.in. to about 2.5 g/sq.in.