F-factor Floors
These constructions will be applied only to underground wall surfaces during the building drawing process. F-factor walls differ from the usual wall constructions, in that it describes an entire construction rather than the individual layers. It is used only when the floor area, exposed perimeter, and the F-factor are available. This construction type creates an equivalent layer-by-layer construction model for the slab-on-grade or underground floor in order to approximate the heat transfer through the floor. This model takes into consideration the thermal mass of the earth soil.
The only three inputs are:
F-factor – The F-Factor represents the heat transfer through the floor, induced by a unit temperature difference between the outside and inside air temperature, per linear length of the exposed perimeter of the floor. The unit for this input is W/mK. ASHRAE Standard 90.1 and California Title 24 specify maximum F-factors for slab-on-grade or underground floors depending on space types and climate zones.
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Default value:
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blank
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Min & Max:
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0 < x <= 100,000
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Typical Range:
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1 to 12 W/m2K; 0.01 to 1.0 Btu/(hr•ft2•°F)
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Units:
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W/(m2K); Btu/(hr•ft2•°F)
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Area - This field is not displayed in the library. It will be automatically populated once the construction is assigned to a surface during the building drawing process. It describes the area of the slab-on-grade or underground floor.
Exposed perimeter - This field is not displayed in the library. It will be automatically populated once the construction is assigned to a surface during the building drawing process. It describes the exposed (direct contact with ambient air) perimeter of the slab-on-grade or underground floor.
