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