Cool Roofs: Cost Effective Technology for Better Buildings, Healthier Cities and a Cooler Planet
2 likes1,385 views
The Global Cool Cities Alliance (GCCA) promotes the adoption of cool roofs to enhance solar reflectance and mitigate climate change impacts. Cool roofs significantly reduce energy usage, improve building longevity, and contribute to public health by lowering urban heat effects. The GCCA is developing a roadmap for implementing these strategies to create cooler, more resilient urban environments.
Cool Roofs: Cost Effective Technology for Better Buildings, Healthier Cities and a Cooler Planet
- 1. Cool Roofs IEA Workshop November 17, 2011 Kurt Shickman kurt@globalcoolcities.org 001-202-550-5852 GlobalCoolCities.org
- 2. Global Cool Cities Alliance (GCCA) The Global Cool Cities Alliance is dedicated to advancing policies and actions that increase the solar reflectance of our buildings and pavements as a cost-effective way to promote cool buildings, cool cities, and to mitigate the effects of climate change through global cooling. 2
- 3. Cool surfaces are a high-impact, short-payback investment that: • Improves buildings by cutting net energy use, help roofs and the equipment on them last longer, and improve the comfort of unconditioned buildings. • Generates significant economic and societal benefits by reducing heat and pollution related illness and death in urban areas. • Helps us both mitigate and adapt to climate change risks. 3
- 4. How Cool Roofs Work Air Temperature 37°C (99°F) Cool surfaces are measured by how much light they reflect (Solar Reflectance) and how efficiently they shed heat (Thermal Emittance). 4
- 5. The Benefits: Cooler Buildings • Cool roofs can cut energy use by 10 to 20 percent on the top floor of conditioned buildings – often avoiding cooling load at the most expensive times of the day. • UHI accounts for 5 – 10% of U.S. peak electricity demand for A/C. • 2-4% more demand per 1° C temperature increase above 20°C • $735 million in energy costs savings in the U.S. commercial buildings. • Cooler surface temperatures may help the roof and the equipment on it last longer. • Cool roofs improve the comfort and “live-ability” of unconditioned buildings. 5
- 6. Electricity Load and Temperature Data from New Orleans, LA Adapted from Sailor, D. J. 2002. Urban Heat Islands, Opportunities and Challenges for Mitigation and Adaptation. Sample Electric Load Data for New Orleans, LA (NOPSI, 1995). North American Urban Heat Island Summit. Toronto, Canada. 1–4 May 2002. Data courtesy Entergy Corporation. 6
- 7. Electricity Load and Temperature Source: Lawrence Berkeley National Lab 7
- 8. Cool Materials Reflectance of common roofing materials and the temperature increase above ambient. Source: Lawrence Berkeley National Laboratory Heat Island Group 8
- 9. Not just white Regal White Rawhide Slate Blue Standard SR .67 Standard SR .47 Standard SR .21 Cool SR .72 Cool SR .56 Cool SR .33 Hartford Slate Bronze Brick Red Charcoal Gray Green Standard SR .25 Standard SR .14 Standard SR .11 Standard SR .08 Cool SR .30 Cool SR .28 Cool SR .28 Cool SR .26 9
- 10. Cool Colors UV visible near-infrared 1.0 Solar Irradiance Distribution Normalized Solar Irradiance 0.9 0.8 ■ 6.6% ultraviolet (300 - 400 nm) 0.7 ■ 44.7% visible (400 - 700 nm) 0.6 ■ 48.7% near-infrared (700 - 2500 nm) 0.5 0.4 0.3 Air Mass 1 Global Horizontal (AM1GH) Solar Irradiance 0.2 0.1 0.0 250 500 750 1000 1250 1500 1750 2000 2250 2500 Wavelength (nm) 10
- 11. Trends in Cool Materials • Staying cleaner, longer – improved aged material values • More “cool” colors - expanding the broad set of available reflective color options • Directional reflectivity - good for sloped roofs Brick Red Charcoal Gray • Clear reflective coatings – an option that balances reflectivity and aesthetics Standard SR .14 Cool SR .28 11
- 12. Trends in Cool Materials – continued • Color-shifting materials – thermo- and electro-chromic (more focused on windows currently) • Advances in testing – accelerated aging processes • Pavements – longevity by material and application. Brick Red Charcoal Gray • Research – broaden geographic diversity of data, field testing, additional modeling and testing of large-scale climate benefits. Standard S .25 Standard SR .14 Cool SR .30 Cool SR .28 12
- 13. Strategies for Cool Communities Source: Lawrence Berkeley National Laboratory Heat Island Group 13
- 14. Roadmap for implementation A preview of a guide being developed for R20 – Regions of Climate Action Policies Programs (e.g., codes, ordinances, (e.g., demonstrations, volunteer incentives) efforts, workforce training) Foundation Activities (e.g., information gathering, building support and capacity) 14
- 15. GCCA envisions a future in which our urban environments are cooler, more resilient and more efficient. Join us! Kurt Shickman kurt@globalcoolcities.org 001-202-550-5852 GlobalCoolCities.org 15