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. If you have a large facility that purchases electricity with a demand charge, run the Peak version of the calculator in order to include the savings in peak demand charges from using solar radiation control.
  • What you get out of this calculator is only as good as what you put in. If you click here , you'll find help in figuring out the best input values. Some things, such as the weathering of the solar radiation control properties and the effects of a plenum, are especially important. You'll also find help in figuring out your heating and cooling system efficiencies and proper fuel prices.
  • 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
Click to see Data for All 243 Locations

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] 

Oak Ridge National Laboratory is managed by UT-Battelle for the Department of Energy