Ventilation: Approved Document F, Volume 2 — Buildings other than dwellings

A O N L I N E V E R S I O N Appendix A: Key terms Except for the items marked * (which are from the Continuous operation Uninterrupted running of a Building Regulations 2010), these definitions apply mechanical ventilation device, such as mechanical only to Approved Document F, Volume 2: Buildings extract ventilation or mechanical supply and other than dwellings. extract ventilation. The air flow rate provided by mechanical ventilation need not be constant but Air permeability The measure of airtightness of may be varied, under either manual or automatic the building fabric. It is defined as the air leakage control, in response to the demand for removal of rate per hour per m2 of envelope area at the test pollutants or water vapour. reference pressure differential of 50Pa. Dwelling A self-contained unit designed to Airtightness The resistance of the building accommodate a single household. envelope to infiltration when ventilators are closed. The greater the airtightness at a given Equivalent area A measure of the aerodynamic pressure difference across the envelope, the lower performance of a ventilator. It is the area of a the infiltration. sharp-edged circular orifice through which air would pass at the same volume flow rate, under an Automatic controls A system whereby a identical applied pressure difference, as through ventilation device is adjusted by a mechanical or the opening under consideration. electronic controller that responds to a relevant stimulus. That stimulus usually relates to the Expert advice Advice from a suitably qualified humidity of the air in a room, pollutant levels, competent person. Examples from the ventilation occupancy of the space or pressure difference industry of a person competent to give expert across the device. advice include a chartered or professional engineer, a building services specialist, a specialist Background ventilator A small ventilation opening ventilation manufacturer or members of designed to provide controllable whole building professional trade bodies. ventilation. Extract ventilation The removal of air directly Bathroom A room that contains a bath or from an internal space or spaces to the outside. shower and which can also include sanitary Extract ventilation may be by natural means or accommodation. by mechanical means (e.g. by an extract fan or a Building control body A local authority or an central system). approved inspector. Free area The geometric open area of a ventilator. Common space A space where large numbers of Habitable room A room used for dwelling people are expected to gather (e.g. a shopping mall purposes but which is not solely a kitchen, utility or foyer of a cinema or theatre) or which is used room, bathroom, cellar or sanitary accommodation. mainly for circulation in buildings which do not contain dwellings (e.g. a corridor or lift lobby in an Infiltration The uncontrolled exchange of air office building). This does not include areas used between the inside and outside of a building, solely or principally for circulation in buildings through gaps and cracks. containing dwellings, including corridors or lift Intermittent operation When a mechanical lobbies in blocks of flats. ventilator does not run all the time, usually running only when there is a particular need to remove pollutants or water vapour (e.g. during cooking or bathing). Intermittent operation may be under either manual control or automatic control. 24 Approved Document F Volume 2, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N