ASHRAE Terminology

an extension or increase in floor area or height of a building outside of the existing building envelope.

a room or building, or portions thereof, including computer rooms being served by the data center systems, serving a total ITE load greater than 10 kW and 20 W/ft2 (215 W/m2) of conditioned floor area.

the floor area substantially illuminated by daylight.

an expression of the annual energy used or calculated to be used by a building or building space per unit of gross floor area. Expressed in MBtu/ft2·yr (watts-hours/m2·yr).

the horizontal area within the inside perimeter of the exterior walls of the building space. Also, the sum of the areas of several floors of the building including basements, mezzanine, intermediate floored tiers, and penthouses of headroom height, measured from the exterior faces of exterior walls or from the centerline of walls separating buildings but excluding covered walkways, open roofed-over areas, porches and similar spaces, pipe trenches, exterior terraces or steps, chimneys, roof overhangs, and similar features.

the gross floor area of the building envelope, excluding slab-on-grade floors.

the gross floor area of a conditioned space.

the sum of the floor areas of all the spaces within the building with no deductions for floor penetrations other than atria. Gross floor area is measured from the exterior faces of exterior walls or from the centerline of walls separating buildings, but it excludes covered walkways, open roofed-over areas, porches and similar spaces, pipe trenches, exterior terraces or steps, roof overhangs, parking garages, surface parking, and similar features.

the gross floor area of lighted spaces.

the gross floor area of semiheated spaces.

the floor area of an occupiable space defined by the inside surfaces of its walls but excluding shafts, column enclosures, and other permanently enclosed, inaccessible, and unoccupiable areas. Obstructions in the space such as furnishings, display or storage racks, and other obstructions, whether temporary or permanent, are considered to be part of the net occupiable area.

dimensionless value calculated from the leakage area, building height, and floor area that describes the relative airtightness of the building envelope.

an enclosed space within a building that is heated by a heating system whose output capacity is greater than or equal to 3.4 Btu/h·ft2 (10 W/m2) of floor area but is not a conditioned space.

a crawlspace with an open vent area 1/150th of its floor area with vents distributed over all exterior surfaces.