Cool Roof Calculator

Cool Roof Calculator logo.

Many reflective roof coatings and membranes are now available for low-slope roofs. These coatings help to reduce summer air-conditioning loads, but can also increase the winter heating load. The Cool Roof Calculator will estimate both how much energy you'll save in the summer and how much extra energy you'll need in the winter. Cool Roof Calculator provides answers on a 'per square foot' basis, so you can then multiply by the area of your roof to find out your net savings each year.

Keywords

reflective roof, roofing membrane, low-slope roof

Validation/Testing

The Radiation Control Fact Sheet describes both the analytical and experimental results that went into the calculator's development.

Expertise Required

None

Users

Calculator provided as a CD to Roof Coatings Manufacturers Association for distribution to their members - probably 200+., also used on the web by unknown numbers.

Audience

Two principle classes of users: potential customers/building owners and roofing surface sellers/installers.

Input

User selects location, enters the proposed roof's R-value, reflectance, emittance, electricity and fuel prices, hvac system efficiencies.

Output

filled-in fields on same web page used for input. Values include: net savings, cooling savings, heating penalties, alternate way (added R-value) to achieve same savings, annual HDD, annual CDH, annual solar load, cooling load for black roof, heating load for black roof, cooling load for proposed roof, heating load for proposed roof.

Computer Platform

Web browser with Java

Programming Language

Java

Strengths

Good scoping tool, help to define situations where a reflective surface is a winner or a loser.

Weaknesses

Shouldn't be used for absolute estimate of savings - because based on 'generic' building definition. Fact sheet includes some caveats - such as shouldn't be used for buildings with an enclosed attic.

Contact

Company:

Oak Ridge National Laboratory

Address:

United States

Telephone:

+1 (865) 574-9335

Facsimile:

+1 (865) 574-9354

E-mail:

PETRIETW@ornl.gov

Website:

http://www.ornl.gov/sci/roofs+walls/facts/CoolCalcEnergy.htm

Availability

Free to use on the web. Stand-alone version on CD available on request to technical contact listed above.