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Concepts In Passive Design #3 Passive Cooling Categorizations, Florida Solar Energy Center

FSEC Energy Research Center®

Editor's Note: While passive solar heating is relatively well evolved, passive cooling is only on the threshold of development, and many of its terms are new to the practicing professional. At the Fourth Annual Passive Cooling Conference this problem was addressed by William W. Holmes of the University of Nebraska with the presentation of a 10-point categorization of cooling techniques. We are indebted to Mr. Holmes for this contribution to the emerging field of passive cooling and present it here as a point of departure and working vocabulary for the design professional.

Concepts In Passive Design #1 Roof Overhangs, Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

A major source of heat in buildings is direct solar radiation through windows--welcome in cold weather, but a problem in hot weather. Since Florida has such a lengthy cooling season, it is most important to protect windows from the sun; however, there are times between November and March when some heat is needed. Fortunately, the change in the sun's path from summer to winter is such that a properly designed roof overhang can protect south-facing windows from the high summer sun, yet allow the lower winter sun to come in.

Thermosiphon System, Florida Solar Energy Center

FSEC Energy Research Center®

In a THERMOSIPHON SYSTEM, cold water from the bottom of the elevated storage tank flows to the lowest point in the system (which is the bottom of the solar collector).

As it is warmed it becomes less dense and flows up to a side port near, but not at, the top of the storage tank. If the tank is about two feet above the top of the collector, the system will not back-siphon at night. If back-siphoning were to occur, the warm water would be cooled during its passage through the dormant collector. Thermosiphoning systems have no moving parts and …