DOE Cool Roof Calculator
Estimates Energy and Peak Demand Savings for Flat Roofs with NonBlack Surfaces
 Developed by the U.S. Department of Energy's Oak Ridge National Laboratory (Version 2.0)
 This version of the calculator is for large facilities that purchase electricity with a demand charge based on peak monthly load. If you have a small or mediumsized facility that purchases electricity without a demand charge, run the CoolCalcEnergy version to estimate the savings in energy 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 nonblack roofs, print out results of separate estimates for each vs. a black roof. Manually compute the difference in savings to compare the two nonblack roofs.
 If your energy costs are determined with both onpeak and offpeak rates, print out results of separate estimates with onpeak then offpeak rates. Use appropriate demand charges for the same roof in both estimates. Judge what fraction of the savings with onpeak rates is appropriate.
My State  
My City  
Click to see Data for All 243 Locations  
My Proposed Roof:  
Rvalue (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) [$/KWh]  
Air conditioner efficiency (COP) over cooling season (HIGH=2.5; AVG=2.0; LOW=1.5)  
Energy source for heating (choose one)  Electricity Fuel 
If electricity, wintertime cost (HIGH=0.20; AVG=0.10; LOW=0.05) [$/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)  
My Electricity Demand Charges and Duration:  
Demand charge during cooling season (HIGH=15.00; AVG=10.00; LOW=5.00) [$/KW]  
Months charged for peak demand (Typical = 6) []  
Total Annual Energy + Demand Savings (relative to a black roof) [$/ft² per year]  
Cooling energy savings [$/ft² per year]  
Heating energy savings (heating penalty if negative) [$/ft² per year]  
Cooling season demand savings [$/ft² per year]  
Insulation in
Black Roof for Same Total Annual Energy Savings (ignores demand savings): 

Upgrade from
R to
R[h·ft²·°F/Btu]


Details of Energy and Demand Savings:  
Heating degree days for location chosen [Annual °Fday]  
Cooling degree days for location chosen [Annual °Fday]  
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]  
Average heat load reduction during cooling season [Btu/ft² each month]  
Maximum heat load reduction during cooling season [Btu/ft²] 
