1 special infrared reflective pigments make dark roofs reflect almost like white roofs performance...
TRANSCRIPT
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Special Infrared Reflective Pigments Make Dark Roofs
Reflect Almost LikeWhite Roofs
Performance of Exterior Envelopes of Whole Buildings
IXDecember 9, 2004
LBNL ORNL
INDUSTRY
COLLABORATIVE R&D
COLLABORATIVE R&D
CECDOE
Ken Loye, Scott Kriner, Bob Scichili
W. Miller,A. Desjarlais
H. Akbari,P. Berdahl,R. Levinson,S. Wiel
Chris Scruton
Marc Lafrance
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Project Goals
• Bring cool colored roofing materials to market
• Accelerate market penetration of cool metal, tile, wood shake, and shingle products
• Measure and document laboratory andin-situ performance of roofing products
• Measure and document improvements in the durability of roofing expected to arise from lower operating temperatures
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Project Team
LBNL
– Steve Wiel(Project Director) [email protected]
– Hashem Akbari [email protected]
– Paul Berdahl
[email protected] – Ronnen Levinson
ORNL
– André Desjarlais [email protected]
– Bill Miller
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Why are the Cool Roof Color Materials (CRCM) Cooler?
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Identified and CharacterizedPigments w/High Solar Reflectance
LBNL
• Database online at http://CoolColors.LBL.gov– contact R. Levinson for more info
• Describes 233 pigmented CRCM coatings– 87 masstones (pure colors)– 57 ratio 1:4 tints (new!)– 57 ratio 1:9 tints (new!)– 32 ratio 1:1 nonwhite mixtures (new!)
• Possible future additions– ratio 1:4, 4:1 nonwhite mixtures
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Characterized Nonwhite MixturesCool Color Combinations
• Prepared, characterized nonwhite mixtures– equal volumes of each color paint– Computed Kubelka-Munk absorption and scattering coefficients (K, S)
• Coating design software requires– database of pigment properties (ready)
– optimization algorithm (to be chosen)
– model for absorption, scattering of mixture
• Simple volumetric model: each component contributes volumetrically to absorption K and scattering S of mix
Kmix = ∑ ci Ki
Smix = ∑ ci Si
where ci = volume fraction of component i
LBNL
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Developing Prototype Cool Dark Brown Shingle (representative image)
• Matches standard dark brown shingle
• Solar reflectanceSR > 0.2
• Next version may achieve SR > 0.25 (Energy Star)
LBNL ORNL
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CooL Tile IR CoatingTM Applied to Concrete Tile
COOL TILE IR COATING™ technology was developed by Joe Reilly of American Rooftile Coatings
ORNL LBNL
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COOL CEDAR SHAKES POSE POTENTIAL IMPROVEMENT IN FIRE RATING
ORNL
Cedar Shake roof 16-yrs of exposure
John Goveia (TRS) Martinez, CA
LBNL
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SR boosted a factor of 6 greater than dark roofing
COOL PAINTED METAL WITH PVDF “polyvinylidene fluoride” base coatORNL LBNL
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Accelerated Weathering to Check Pigment Fade Resistance
Total Color Difference measure E
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222 baLE
ORNL LBNL
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Three Years of Field Exposure in Florida Shows Improved Fade Resistance
Painted PVDF metals
ORNL
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Field-testing at Cavalli Hills Subdivision Fair Oaks, CA
House-1 4979 Mariah Place
House-3 4987 Mariah Place
COOL TILE IR COATING™COOL TILE IR COATING™41% reflective
Finished with Low-profile Concrete Tile and Stucco
ORNL
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Drops Attic Temperature ~4oC (7oF) at Solar Noon
Cool Coating on Concrete Tile Reduces Heat Flux Through Ceiling
ORNL
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Field-testing at Cavalli HillsSubdivision Fair Oaks, CA
House-4 4991 Mariah Place
House-2 4983 Mariah Place
Ultra Cool 31% reflectance
South facing roof
Finished with Painted Metal Shingles and Stucco
ORNL
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Cool Coating Reduces Heat Flux Through South Facing Roof Deck
Painted Metal Roofs
ORNL
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Materials Testing at CA Exposure Sites
Clay and Painted Metal exposed for 1½ years
ORNL
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Rawhide and Slate Bronze Painted Metal Solar Reflectance
Climatic zone affects loss of reflectance
ORNL
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Airborne Pollutants Appear to have a Strong Effect on the Loss of Reflectance
Loss of reflectance changes with roof slope
White Buff Clay Tile
ORNL
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Mission Tiles Yield the Lowest Roof Heat Flux and Attic Air Temperature
Synergism observed between SR and batten – counter batten venting
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AtticSim tool predicts thermal performance of residential attics
Reflectance and emittance
Ceiling and roof insulation
Attic Ventilation
Roof Orientation
Roof slope
Roof thermal mass
Moisture (external and internal)
Deck ventilation
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Atticsim Predicts Attic Ventilation within Range of Literature Data
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AtticSim Validation for Direct Nailed Shingle Roof tested on ESRA
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Potential Energy Savings Gained for Painted Metal Implementing CRCMs
R-19 Ceiling Insulation (IECC, 2000)
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In more moderate climates the heating load penalty offsets the cooling energy savings
CRCMs do not yield an energy savings in cold climates
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Savings based on the incremental gains over an SR08E80 roof with R-19 insulation in Dallas
electricity $0.10 per kWh; natural gas $10.00 per 1000 ft3
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Savings are based on the incremental gains over an SR08E80 roof with R13 insulation in Miami
electricity $0.10 per kWh; natural gas $10.00 per 1000 ft3
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SUMMARYCOOL ROOF COLOR MATERIALS
Demonstration sites proving energy savings generated by “Cool Colors”
Tile, Metal, Asphalt shingle, Cedar Shake Attic Assembly on ESRA at ORNL Field exposure sites in California
Benefits from infrared pigment study Energy savings for homeowners and businesses
Mitigate CO2 emissions polluting environment
Utilities will cut peak demands
Characterized and Identified “Cool Colors”
Web database describes 233 pigmented coatings
Developing engineering methods to apply them for optimum reflectance
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Cool Colors Project Website
• Project information (including copies of this presentation) available online at
http://CoolColors.LBL.gov