Cool Roofs Cool Your Buildings, Your Cities, and OUR PLANET

1. Cool Roofs Cool Your Buildings, Your Cities, and OUR PLANET Arthur H. Rosenfeld Former Commissioner,California Energy Commission Guest Faculty Scientist,Lawrence Berkeley National Lab AHRosenfeld@LBL.govHome-Office Phone: 510-527-1060 Cell Phone: 916-205-3965 Ronnen Levinson, Ph.D. Acting Leader, Heat Island GroupLawrence Berkeley National Lab RMLevinson@LBL.govtel. 510-486-7494http://CoolColors.LBL.gov Washington DC, May 2010 This talk available on CoolWhitePlanet.org 1

2. I. Urban heat islands and cool roofs

3. Summer in the city summer urban heat island 3 3

4. Bird’s eye view of urban land use • The surface of Sacramento, CAis about • 20% roofs • 30% vegetation • 40% pavement ~ 1 km2 4 4

5. Reflective roofs stay cooler in the sun 50 40 30 20 10 0 Galvanized Steel IR-Refl. Black Black Paint White Cement Coat. Temperature Rise (°C) Green Asphalt Shingle Al Roof Coat. Red Clay Tile White Asphalt Shingle White Paint Lt. Red Paint Lt. Green Paint Optical White 0.0 0.2 0.4 0.6 0.8 1.0 Solar Absorptance 5

6. White roofs, cool-colored roofs OLD NEW AC savings ~ 15% flat, white AC savings ~ 5% pitched,cool & colored AC savings ~ 10% AC savings ~ 10% pitched, white 6 6

7. Potential U.S. white-roof benefits • Retrofitting 80% of U.S. air-conditioned commercial buildings (2.1B m2) would annually save • $735M • 6.2 Mt CO2 (=1.2M cars) • 9.9 kt NOx (=0.6M cars) • 26 kt SO2 • 126 kg Hg through energy conservation • Product lifetime energy savings has present value of $11B New York Times, 30 July 2009 7 7

8. II. Cool roofs of tomorrow

9. Advanced cool-colored asphalt shingles today’s cool asphalt shinglesreflect ~ 25% of sunlight CourtesyElk Corporation Solar reflectance ≥ 25% • Prototype cool asphalt shingles • use new coating process • offers wide color palette • reflect up to 35% of sunlight • can save up to 60% more energy 9

10. Advanced white roof coatings, membranes White roof coatings, membranes soil rapidly, lose solar reflectance (SR) initial SR ~ 0.80 aged SR ~ 0.55 How to keep white roofs clean and reflective? reduce leaching of plasticizers decrease surface roughness & stickiness photocatalyticself-cleaning photoinduced hydrophilicity both roofs exposed for 9 years in Florida White metal roof stays clean,saving 70% more energy than soiled white coating. 10

11. III. White roofs around the world

12. White is “cool” in Bermuda 12 12

13. …in Santorini, Greece 13 13

14. …in Hyderabad, India …and widelyin the state of Gujarat, India. 14 14

15. Walmart store in Chico, CA 15 15

16. Congratulations to UC Davis 16 16

17. White roofs are popular in Tucson, AZ 17 17

18. …and in Punta Gorda, FL 18 18

19. Washington, DC (Federal) has problems 19 19

20. Pentagon 20 20

21. IV. Cooling our planet

22. Solar-reflective surfaces cool the globevia “negative radiative forcing” Source: Intergovernmental Panel on Climate Change (IPCC) 22 22

23. White roofs cool your buildings and citiesand (this is NEW)… our planet! 23

24. GLOBAL COOLING: making 100 m2 (1000 ft2) of gray roofing white offsets the emission of 10 t of CO2 24

25. 3 papers and 1 memo estimate tonnes of CO2 offset by 100 m2 (1000 ft2) of white roofing It is assumed that of 1 tonne of CO2emitted only 0.55 tonnes remain in the atmosphere after one year, so the atmospheric and emitted columns are just in the ratio of 0.55/1. 25

26. How much CO2 equivalent is offset if we whiten all eligible urban flat roofs world-wide? • Answer: 15 gigatonnes (Gt) • one third of a year’s worldwide emission • gigatonne = billion metric tons • If implemented over 15 years (the life of a roof or a program) this is ~ 1 Gt/year. • 1 Gt/year is equivalent to offsetting the emissions of 250 million cars for 15 years. • There are about 600 million passenger cars world wide, and they each emit ~ 4 t CO2/year. 26

27. V. What to do now

28. Strategies

29. Building standards For planning purposes,follow the lead of the California Public Utilities Commission and internalize externalities.Currently it’s only $10/tonne CO2, but it’s a start. Thus, California already plans to incorporate externalities when optimizing building standards. Externalities justify cool roofs on non-air conditioned buildings. Apply externalities also to cool pavements, vehicle roofs, even train roofs. 29

30. 100 Cool Cities would coordinatemany initiatives and trade associations 30

31. 100 Cool Cities initiative DOE should offer: U.S. technical support to promote local study teams in China, India, etc. Cash incentives to first 10 cities Funding for Cool Cities staff in U.S. 31

32. Agreements Well before the July Ministerial Conference, DOE and State Department should convince5 - 10 charter countries to sponsor an agreementto promote Cool Roofs.Interested countries already include Brazil, China, India, and Australia. 32

33. Resources on the web • Cool White Planet • CoolWhitePlanet.org • Cool Colors Project • CoolColors.LBL.gov • Heat Island Group • HeatIsland.LBL.gov • Cool Communities Project • CoolCommunities.LBL.gov • Roof Savings Calculator • RoofCalc.com • Cool Roof Rating Council • CoolRoofs.org • Cool California • CoolCalifornia.org • EPA Heat Islands • epa.gov/hiri • Energy Star Cool Roofs • EnergyStar.gov 33 33