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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) SWiel@LBL.gov

– Hashem Akbari H_Akbari@LBL.gov

– Paul Berdahl

PHBerdahl@LBL.gov – Ronnen Levinson

RMLevinson@LBL.gov

ORNL

– André Desjarlais yt7@ORNL.gov

– Bill Miller

wml@ornl.gov

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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