# 3280.102 Definitions.
*Air, exhaust* means air discharged from any space to the outside by an exhaust system.
*Air, outdoor* means air from outside the building taken into a ventilation system or air from outside the building that enters a space through infiltration or natural ventilation openings.
*Exhaust system* means one or more exhaust fans that remove air from the building, causing outdoor air to enter by ventilation inlets or normal leakage paths through the building envelope.
*Gross floor area* means all space, wall to wall, including recessed entries not to exceed five (5) square feet and areas under built-in vanities and similar furniture. When the ceiling height is less than that specified in § 3280.104, the floor area under such ceilings must not be included in the gross floor area. Floor area of closets must also not be included in the gross floor area.
*Habitable room* means a room or enclosed floor space arranged for living, eating, food preparation, or sleeping purposes not including bathrooms, foyers, hallways, and other accessory floor space.
*Laundry area* means an area containing or designed to contain a laundry tray, clothes washer and/or clothes dryer.
*Mechanical ventilation* means the active process of supplying air to or removing air from an indoor space by powered equipment such as motor-driven fans and blowers but not by devices such as wind-turbine ventilators and mechanically operated windows.
*Natural ventilation* means ventilation occurring as a result of natural forces, such as wind pressure or differences in air density, through intentional openings such as open windows or doors.
*Supply system* means one or more fans that supply outdoor air to the building, causing indoor air to leave by normal air leakage through the building envelope.
*Ventilation* means the process of supplying outdoor air to or removing indoor air from the manufactured home by natural or mechanical means. Such air may or may not have been conditioned.
[89 FR 75744, Sept. 16, 2024]