Heat Island Group, Lawrence Berkeley National Laboratory 11 Arthur H. Rosenfeld Former Commissioner, California Energy Commission Guest Faculty Scientist, Lawrence Berkeley National Lab Home-Office Phone: Cell Phone: This talk available on CoolWhitePlanet.orgCoolWhitePlanet.org Cool Roofs Cool Your Buildings, Your Cities, and OUR PLANET Washington DC, May 2010 Ronnen Levinson, Ph.D. Acting Leader, Heat Island Group Lawrence Berkeley National Lab tel

Heat Island Group, Lawrence Berkeley National Laboratory 2 I. Urban heat islands and cool roofs

Heat Island Group, Lawrence Berkeley National Laboratory 33 Summer in the city 3 summer urban heat island

Heat Island Group, Lawrence Berkeley National Laboratory 44 Bird’s eye view of urban land use ~ 1 km 2 The surface of Sacramento, CA is about 20% roofs 30% vegetation 40% pavement 4

Heat Island Group, Lawrence Berkeley National Laboratory 55 Reflective roofs stay cooler in the sun Temperature Rise (°C) Galvanized Steel IR-Refl. Black Black Paint Green Asphalt Shingle Red Clay Tile Lt. Red Paint Lt. Green Paint White Asphalt Shingle Al Roof Coat. Optical White White Paint White Cement Coat. Solar Absorptance

Heat Island Group, Lawrence Berkeley National Laboratory 66 White roofs, cool-colored roofs flat, white pitched, white pitched, cool & colored OLD NEW 6 AC savings ~ 10% AC savings ~ 15% AC savings ~ 5% AC savings ~ 10%

Heat Island Group, Lawrence Berkeley National Laboratory 77 Potential U.S. white-roof benefits Retrofitting 80% of U.S. air- conditioned commercial buildings (2.1B m 2 ) would annually save – $735M – 6.2 Mt CO 2 (=1.2M cars) – 9.9 kt NO x (=0.6M cars) – 26 kt SO 2 – 126 kg Hg through energy conservation Product lifetime energy savings has present value of $11B New York Times, 30 July

Heat Island Group, Lawrence Berkeley National Laboratory 8 II. Cool roofs of tomorrow

Heat Island Group, Lawrence Berkeley National Laboratory 99 Advanced cool-colored asphalt shingles 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 today’s cool asphalt shingles reflect ~ 25% of sunlight Courtesy Elk Corporation Solar reflectance ≥ 25%

Heat Island Group, Lawrence Berkeley National Laboratory 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 – photocatalytic self-cleaning – photoinduced hydrophilicity White metal roof stays clean, saving 70% more energy than soiled white coating. both roofs exposed for 9 years in Florida

Heat Island Group, Lawrence Berkeley National Laboratory 11 III. White roofs around the world

Heat Island Group, Lawrence Berkeley National Laboratory 12 White is “cool” in Bermuda 12

Heat Island Group, Lawrence Berkeley National Laboratory 13 …in Santorini, Greece 13

Heat Island Group, Lawrence Berkeley National Laboratory 14 …in Hyderabad, India …and widely in the state of Gujarat, India. 14

Heat Island Group, Lawrence Berkeley National Laboratory 15 Walmart store in Chico, CA 15

Heat Island Group, Lawrence Berkeley National Laboratory 16 Congratulations to UC Davis 16

Heat Island Group, Lawrence Berkeley National Laboratory 17 White roofs are popular in Tucson, AZ 17

Heat Island Group, Lawrence Berkeley National Laboratory 18 …and in Punta Gorda, FL 18

Heat Island Group, Lawrence Berkeley National Laboratory 19 Washington, DC (Federal) has problems 19

Heat Island Group, Lawrence Berkeley National Laboratory 20 Pentagon

Heat Island Group, Lawrence Berkeley National Laboratory 21 IV. Cooling our planet

Heat Island Group, Lawrence Berkeley National Laboratory 22 Solar-reflective surfaces cool the globe via “negative radiative forcing” Source: Intergovernmental Panel on Climate Change (IPCC) 22

Heat Island Group, Lawrence Berkeley National Laboratory 23 White roofs cool your buildings and cities and (this is NEW)… our planet!

Heat Island Group, Lawrence Berkeley National Laboratory 24 GLOBAL COOLING: making 100 m 2 (1000 ft 2 ) of gray roofing white offsets the emission of 10 t of CO 2

Heat Island Group, Lawrence Berkeley National Laboratory 25 Study (available at CoolWhitePlanet.org) CoolWhitePlanet.org MethodCloud cover esti- mation CO 2 offset (atmos- pheric) per 100 m 2 CO 2 offset (emitted) per 100 m 2 World-wide potential CO 2 offset (emitted) from cool roofs CO 2 offset compared to Akbari et al Akbari et al (LBNL)calculation~ 50%5.5 t10 t24 Gt100% 2 Menon et al (LBNL) GCM + land use model (summer only) GCM7 t13 t30 Gt130% 3 Oleson et al (NCAR) [CO 2 values from private communication between Oleson & Menon] GCM + urban canyon model GCM7 t13 t30 Gt130% 4 VanCuren et al (CARB) measured solar radiation not needed 3 t5 t Addresses CA only; coastal CA is foggy. 50% 3 papers and 1 memo estimate tonnes of CO 2 offset by 100 m 2 (1000 ft 2 ) of white roofing It is assumed that of 1 tonne of CO 2 emitted 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.

Heat Island Group, Lawrence Berkeley National Laboratory 26 How much CO 2 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 CO 2 /year.

Heat Island Group, Lawrence Berkeley National Laboratory 27 V. What to do now

Heat Island Group, Lawrence Berkeley National Laboratory 28 Strategies

Heat Island Group, Lawrence Berkeley National Laboratory 29 Building standards For planning purposes, follow the lead of the California Public Utilities Commission and internalize externalities. Currently it’s only $10/tonne CO 2, 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.

Heat Island Group, Lawrence Berkeley National Laboratory Cool Cities would coordinate many initiatives and trade associations

Heat Island Group, Lawrence Berkeley National Laboratory 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.

Heat Island Group, Lawrence Berkeley National Laboratory 32 Agreements Well before the July Ministerial Conference, DOE and State Department should convince charter countries to sponsor an agreement to promote Cool Roofs. Interested countries already include Brazil, China, India, and Australia.

Heat Island Group, Lawrence Berkeley National Laboratory 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