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Cool Roofs and Urban Heat Islands
USGBC Member Mee7ng
Kurt Shickman June 15, 2015
2
Global Cool Ci)es Alliance (GCCA) The Global Cool Ci7es Alliance is dedicated to advancing policies
and ac7ons that reduce excess urban heat in order to cool buildings, cool ci7es, and to mi7gate the effects of climate change
through global cooling.
CoolRoofToolkit.org
3
4 Source: NASA
What causes urban heat islands?
5 Source: NASA
What causes urban heat islands?
Top 10 most intense UHIs in the U.S.
The average U.S. city is 2.7°F hoQer than surrounding rural areas
5.9°
7.3°
4.8°
4.1°
4.8°
4.7° 4.6° 4.4°
4.3°
4.9°
Source: Climate Central (hQp://www.climatecentral.org/news/urban-‐heat-‐islands-‐threaten-‐u.s.-‐health-‐17919)
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Urban heat is worsened by global climate change…
…and growing at 2x the global average
8
How reflec)ve “cool” surfaces work
Air Temperature 37°C (99°F)
All sorts of roof types and colors are cool
Asphalt Shingles
Clay & Concrete Tiles Metal Roofs
Built-Up Roofs
Coatings
Membranes
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Cool roofs generate net energy cost savings across the U.S.
R-19 roof R-13 walls EER10 A/C
Source: Levinson and Akbari. (2010)Potential benefits of cool roofs on commercial buildings: conserving energy, saving money, and reducing emission of greenhouse gases and air pollutants.
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Peak Demand Savings: Uniform Across Climates
Source: Dr. Jim Hoff, RoofPoint Energy and Carbon Calculator
-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0
Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7-8
BTU
/ 10
0 Ft
2
Base Use Savings Peak Demand Savings
PHOENIX
MINNEAPOLIS
Warmest Climate Zones Coldest Climate Zones
Poten)al Roof-‐Related Base Use and Peak Demand Savings (by North America Climate Zone)
12 Report available at: http://cap-e.com/affordable-housing-smart-roof/
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A 10%ñ in surface reflec0vity and vegeta0on cut outside temperatures by: DC: 0.5°F, leading to a 7% mortality reduc7on LA: 0.5°F, leading to a 1% mortality reduc7on NYC: 0.3°F, leading to a 9% mortality reduc7on Bal7more: : 0.5°F, leading to a 2% mortality reduc7on
Source: Global Cool Ci7es Alliance
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Cooling with reflec)vity: A real-‐world case
The whitewashed greenhouses of Almeria, Spain have cooled the region by 0.8 degrees Celsius each decade compared to surrounding regions, according to 20 years of weather sta7on data.
Source: Google Earth
15
A li[le cooling goes a long way…
15 Source: Maryland Commission on Climate Change
EPA Compliance Std = 75
Transition Zone
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A li[le cooling goes a long way (cont)…
Source: Weather Underground, PJM Interconnec7on (PJME). Data includes 2009-‐2014
Max Daily Temperature (F)
Daily Load (kWh)
80F 90F 95F -‐ 99F 718 MWh 870 MWh 999 MWh Baseline 21% 39%
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Global Cooling
• Whitening 1000 f2 of grey roof offsets the warming effect of 10 tons of GHGs.
• Total poten7al is 24 Gt of offsets, or 500 coal power plants worth of emissions, or removing half the world’s cars for 20 years.
1999 2015 2006
ASHRAE 90.1, 1999
- credit
California Title 24 2001 - credit
City of Chicago 2001 -
requirement
IECC 2003 - allows
compliance via ASHRAE
California Title 24 2005 - requirement
IECC 2012 - requirement
New York City 2012
Philadelphia 2010
Washington, DC 2013
Miami 2009
LA 2013
Houston 2008
Dallas 2008
Cool Roofs in the Codes
Florida State 2001 – credit
Washington, DC 2008 – green code
ASHRAE 90.1, 2010
- requirement, with
exemptions
Trend is moving from credits and trade-offs with insulation to requirements
Florida 2010
Phoenix 2013
Baltimore 2015
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Thank You!
kurt@globalcoolci7es.org GlobalCoolCi)es.org CoolRoofToolKit.org @GlobalCoolCity 202-‐550-‐5852
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