Cool Roof Calculator

Estimates Cooling and Heating Savings for Flat Roofs with Non-Black Surfaces

• Developed by the U.S. Department of Energy's Oak Ridge National Laboratory (Version 1.2)
• This version of the calculator is for small and medium-sized facilities that purchase electricity without a demand charge based on peak monthly load.
• To compare two non-black roofs, print out results of separate estimates for each vs. a black roof. Manually compute the difference in savings to compare the two non-black roofs.
• If your energy costs are determined by on-peak and off-peak rates, print out results of separate estimates with on-peak and off-peak rates for the same roof. Judge what fraction of the savings with on-peak rates is appropriate.

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My City	Select a city
My Proposed Roof:
R-value (HIGH=20; AVG=10; LOW=5) [h·ft²·°F/Btu]
Solar reflectance, SR (HIGH=80; AVG=50; LOW=10) [%]
Infrared emittance, IE (HIGH=90; AVG=60; LOW=10) [%]
My Energy Costs and Equipment Efficiencies
Summertime cost of electricity (HIGH=0.20; AVG=0.10; LOW=0.05) [$/KWh]
Air conditioner efficiency (Coefficient of Performance) (HIGH=2.5; AVG=2.0; LOW=1.5)
Energy source for heating (choose one)	Electricity  Fuel
If electricity, wintertime cost (HIGH=0.20; AVG=0.10; LOW=0.05) [$/KWh]
If fuel, cost (Natural gas: HIGH=1.00; AVG=0.70; LOW=0.50) [$/Therm]
(Fuel oil: 2002 East coast=0.85; 2002 Midwest=0.70) [$/Therm]
Heating system efficiency (Furnace or boiler: HIGH=0.8; AVG=0.7; LOW=0.5)
(Electric heat pump: HIGH=2.0; AVG=1.5)   (Electric resistance: 1.0)
Net Savings [$/ft² per year]
Cooling savings [$/ft² per year]
Heating savings (heating penalty if negative) [$/ft² per year]
Insulation in Black Roof to Yield Same Annual Energy Savings:
Upgrade from R- to R- [h·ft²·°F/Btu]
Details of Comparison:
Heating degree days for location chosen [Annual °F-day]
Cooling degree days for location chosen [Annual °F-day]
Solar load for location chosen [Annual Average Btu/ft² per day]
Cooling load for black roof (SR=5%;IE=90%) [Btu/ft² per year]
Heating load for black roof (SR=5%;IE=90%) [Btu/ft² per year]
Cooling load for proposed roof [Btu/ft² per year]
Heating load for proposed roof [Btu/ft² per year]