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Glossary

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A I B I C I D I E I F I G I H I I I J I K I L I M I N

O I P I Q I R I S I T I U I V I W I X I Y I Z

 

R-value

See thermal resistance.

 

Radiant flux

The time rate of flow of radiant energy.

I-P units: Btu/(hft2)

 

Reflectance

The ratio of radiation reflected by a surface to the radiation striking a surface. This ratio ranges from 0.0 (no reflectance) to 1.0 (total reflectance).

 

Reflection

The process whereby, after striking a surface, a portion of the total amount of radiation striking a surface is redirected on the incident side.

 

Relative humidity

The humidity ratio of the air expressed as a percent of the saturation point for a specific temperature.

 

Roofpond

An indirect gain heating and cooling system where the thermal mass, which is water in plastic bags, is located on the roof of the space which is being heated and/or cooled. The roofpond system, traditionally defined as a passive solar system, is best defined as a hybrid system, since its contemporary applications virtually always consist of motorized, retractable panels of insulation. Harold R. Hay, the inventor of the roofpond system, originally patented the roofpond as the SkythermTM system. Historically, roofpond applications have proved to be viable low-cost solutions for both heating and cooling in a wide variety of climate regions. There are two distinct roofpond systems: a flat-roof "southwest" application and a pitched-roof version referred to as the "north" application.

 

 

 

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