Cool Roofing… Cutting Through the Glare May 12 & 13, 2005 Atlanta, Georgia

 Sponsored by –Roof Consultants Institute Foundation (RCIF) –Oak Ridge National Laboratories (ORNL) –National Research Council of Canada (NRC)  Attended by –Over 200 construction and design professionals –Industry media & trade associations  Presented by –30 researchers from universities, government, industry Cool Roofing… Cutting Through the Glare

 Environmental Issues  Economic Issues Cool Roofing…Cutting Through the Glare Key Symposium Topics

 Highly reflective roofs can reduce urban temperatures in the summer….  Reducing ozone formation  Reducing energy costs  Reducing fossil fuel demand Cool Roofing…Cutting Through the Glare Cool Roofs & the Environment

 ….. but the cooling effect of highly reflective roofs may be overstated –Wind effects not always considered –Degradation due to roof aging not fully addressed –Alternative approaches not always considered Cool Roofing…Cutting Through the Glare Cool Roofs & the Environment

Cool Roofing…Cutting Through the Glare Cool Roofs & Wind Effects The Effects of Wind on Roof Surface Air Temperature Air Temperature ( o C) Roof Reflectivity (%) 0 10% 20% 30% 40% 50% 60% 70% 80% Summertime Daily Average and Maximum Air Temperatures for Roof System Reflectivity Simulations Conducted for City of Chicago Source: Dupuis, R. & Graham, M. (2005) “Study on Roof System Reflectivity and Near-Surface Air Temperatures in Chicago, IL.” Paper presented at “Cool Roofing … Cutting Through the Glare”, Atlanta Georgia. No Wind With Wind Effect Added

Cool Roofing…Cutting Through the Glare Cool Roofs & Surface Aging 50% to 60% Reflectivity after 3 Years Reflectivity (%) Exposure (Months) Roof Reflectance After Field Exposure Oak Ridge Laboratories Envelope Systems Research Apparatus (ESRA) Source: Miller, W.A., M. Cheng, S. Pfiffer and N. Byers. (2002). The Field Performance of High-Reflectance Single-Ply Membranes Exposed to Three Years of Weathering in Various U. S. Climates. Oak Ridge, TN: Oak Ridge National Laboratory. 75% + Initial Reflectivity Declines to… Test Membrane A Test Membrane B

Ballasted Roofs Increased Roof Insulation Cool Roofing…Cutting Through the Glare Cool Roof Alternatives

Cool Roof Alternatives: Ballasted Roofs White Roof with 70% Reflectance Black Roof with 5% Reflectance Ballasted Roof with 10 lb. Stone Ballasted Roof with 17 lb. Stone Ballasted Roof with Concrete Pavers Which Roof Saves The Most Energy?

Cool Roof Alternatives: Ballasted Roofs Roof Membrane Surface Temperature: Clear Summer Day In East Tennessee (Oak Ridge National Laboratories) Exposed White TPO Membrane Exposed Black EPDM Membrane Ballasted EPDM Under 10 lb. Stone Ballasted EPDM Under Concrete Pavers Source: Gillenwater, D., Petrie, T., Miller W., & Desjarlais, A. (2005) “Are Ballasted Roof Systems Cool?” Paper presented at “Cool Roofing … Cutting Through the Glare”, Atlanta Georgia. Note: Area Under Curve Indicates Total Heat Absorbed 180ºF 136ºF 122ºF 120ºF

Cool Roof Alternatives: Ballasted Roofs Source: Gillenwater, D., Petrie, T., Miller W., & Desjarlais, A. (2005) “Are Ballasted Roof Systems Cool?” Paper presented at “Cool Roofing … Cutting Through the Glare”, Atlanta Georgia. Roofing Alternative: Roofs with Light Stone Ballast (10 lb. / sq. ft.) Roofs with Heavy Stone Ballast (17-20 lb. / sq. ft.) Roofs with Concrete Pavers Overall Energy Savings: Equivalent to an aged reflective roof (50% reflectivity) Equivalent to a new reflective roof (70% reflectivity) Equivalent to any reflective roof (Up to 100% reflectivity)

Cool Roof Alternatives: Increased Roof Insulation White Roof with 55% Reflectance Black Roof with 5% Reflectance R-20 Insulation R-? Insulation v. What is the R-Value for a Non-Reflective Roof to Provide Equivalent Energy Savings to a Reflective Roof with R-20 Insulation? Source: Hoff, J. L. (2005). “The Economics of Cool Roofing: A Local and Regional Approach.” Paper presented at “Cool Roofing … Cutting Through the Glare”, Atlanta Georgia.

Cool Roof Alternatives: Increased Roof Insulation Source: Hoff, J. L. (2005). “The Economics of Cool Roofing: A Local and Regional Approach.” Paper presented at “Cool Roofing … Cutting Through the Glare”, Atlanta Georgia. Portland Boston New York Pittsburgh Baltimore Cleveland Detroit Indianapolis Chicago Milwaukee Minneapolis Richmond Charlotte Nashville Atlanta St. Louis Little Rock Jacksonville Miami Tampa New Orleans Houston Ft. Worth Phoenix Boulder Cheyenne Boise Reno Portland Seattle SLC Las Vegas Los Angeles Albuquerque Louisville Birmingham Kansas City San Francisco R-21 R-19 R-20 R-23 R-26 R-30 R-33 R-Value For A Non-Reflective Roof To Provide Equivalent Energy Savings to a Reflective Roof with R-20 Insulation

 Scale: What does it mean to the individual building owner?  Location: What does it mean to a building owner in a particular location? Cool Roofing…Cutting Through the Glare Economic Issues

The Economics of Cool Roofing Scale Effects Potential net annual energy savings from reflective roofs for an entire city Source: Lawrence Berkeley National Laboratory Heat Island Group Chicago: $10 Million Dallas: $20 Million Miami: $20 Million Los Angeles: $35 Million New York: $16 Million

Source: DOE Cool Roof Calculator Potential net annual energy savings for a typical 20,000 square foot building Chicago $20 Dallas $520 Los Angeles $300 New York $360 Miami $760 The Economics of Cool Roofing Scale Effects

Source: DOE Cool Roof Calculator Potential net annual energy savings per square foot of roof Chicago $0.001 Dallas $0.026 Los Angeles $0.015 New York $0.018 Miami $0.38 The Economics of Cool Roofing Scale Effects

The Economics of Cool Roofing Regional Differences Climate Metric Heating Degree Days Cooling Degree Days Solar Load (BTU/ Sq. Ft. / Day) U.S. Low* 141 (Miami) 69 (San Francisco) 1061 (Seattle) U.S. High* 7521 (Milwaukee) 4127 (Miami) 1839 (Phoenix) Variance 5234% 5881% 73% * For Standard Metropolitan Statistical Areas Source: DOE Cool Roof Calculator Everyone is aware that there are significant climate differences across the United States…

Energy Source Electricity ($ / KWH) Natural Gas ($ / Therm) U.S. Low* $ (Louisville) $ (Salt Lake City) U.S. High* $ (New York City) $ (Atlanta) Variance 122% 73% * For Standard Metropolitan Statistical Areas Source: Energy Information Administration, June, 2004 …but differences in energy costs are just as important The Economics of Cool Roofing Regional Differences

The Economics of Cool Roofing Building Comparison 55% Reflectance 80% Emittance Elec. Cooling (COP = 2.0) Gas Heat (70% Efficiency) 5% Reflectance 80% Emittance Elec. Cooling (COP = 2.0) Gas Heat (70% Efficiency) R-20 Insulation 20,000 Sq. Ft. v.

Portland Boston New York Pittsburgh Baltimore Cleveland Detroit Indianapolis Chicago Milwaukee Minneapolis Richmond Charlotte Nashville Atlanta St. Louis Little Rock Jacksonville Miami Tampa New Orleans Houston Ft. Worth Phoenix Boulder Cheyenne Boise Reno Portland Seattle SLC Las Vegas Los Angeles Albuquerque Ok. City Louisville Birmingham Kansas City San Francisco $0 $100 $200 $300 $400 $500 $0 $100 $200 $300 $400 $500 Annual Heating / Cooling Cost Savings: Reflective Roof versus Non-Reflective Roof (-$50) (-$100) (-$50) (Dollars per 20,000 Sq. Ft. Roof Area / R-20 Insulation) Source: Hoff, J. L. (2005). “The Economics of Cool Roofing: A Local and Regional Approach.” Paper presented at “Cool Roofing … Cutting Through the Glare”, Atlanta Georgia.

Cool roofs offer tangible benefits for individuals and the community: Energy savings Reduced urban heat island effect Cool Roofing…Cutting Through the Glare Recommendations (For Dallas / Ft. Worth)

Cool Roofing…Cutting Through the Glare Recommendations (For Dallas / Ft. Worth) … but there are several cool roofing alternatives to consider: Reflective membranes Reflective coatings Ballasted membranes

Cool Roofing…Cutting Through the Glare Recommendations (For Dallas / Ft. Worth) … and several important issues must be recognized: The total energy payback is fairly small Less than $0.03 per sq. ft. annually May be inadequate to justify a significant cost up-charge Reflective membranes will age Assume 50% to 55% as a reasonable long-term value Energy payback may be inadequate to justify cleaning & maintenance Roof insulation will lose less long-term energy value