Ventilation: Approved Document F, Volume 1 — Dwellings

O N L I N E V E R S I O N A Heat recovery Applied to mechanical supply f. the building is not a building described in and extract systems or a single room ventilator, classes 1 to 6 in Schedule 2, where previously it extract air is passed over a heat exchanger and the was; recovered heat is put into the supply air. g. the building, which contains at least one dwelling, contains a greater or lesser number of Highly airtight dwellings Dwellings that achieve dwellings than it did previously; one of the following. h. the building contains a room for residential a. A design air permeability lower than 5m3/(h·m2) purposes, where previously it did not; at 50Pa. i. the building, which contains at least one room b. An as-built air permeability lower than 3m3/ for residential purposes, contains a greater (h·m2) at 50Pa. or lesser number of such rooms than it did Infiltration The uncontrolled exchange of air previously; between the inside and outside of a building, j. the building is used as a shop, where it through gaps and cracks. previously was not; or Intermittent operation When a mechanical k. the building is a building described in regulation ventilator does not run all the time, usually running 7(4)(a), where previously it was not. only when there is a particular need to remove pollutants or water vapour (e.g. during cooking Mechanical ventilation with heat recovery A or bathing). Intermittent operation may be under mechanically driven ventilation system that both either manual or automatic control. continuously supplies outdoor air to the inside of the dwelling and continuously extracts indoor air Less airtight dwellings Those dwellings that are not and discharges it to the outside. For the purposes highly airtight dwellings. of this approved document, the guidance for Manual controls A system whereby a ventilation mechanical ventilation with heat recovery applies device is opened and closed, or switched on to centralised or decentralised supply and extract and off, or its performance is adjusted by the systems, with or without heat recovery. occupants of a room or building (see automatic Natural ventilation Ventilation provided by thermal, controls). wind or diffusion effects through doors, windows *Material change of use Defined in regulation 5 as: or other intentional openings without the use of Where there is a change in the purposes for which mechanically driven equipment. For the purposes or the circumstances in which a building is used, of this approved document, natural ventilation so that after that change: refers to a ventilation strategy using background ventilators and intermittent extract ventilation. a. the building is used as a dwelling, where previously it was not; Permanent opening An opening between rooms or floors that has no means of closing it, e.g. an open b. the building contains a flat, where previously it stairwell or two rooms that have been joined by did not; removing part of a wall. c. the building is used as an hotel or a boarding house, where previously it was not; Purge ventilation Manually controlled ventilation of rooms or spaces at a relatively high rate to d. the building is used as an institution, where rapidly dilute pollutants and/or disperse water previously it was not; vapour. Purge ventilation may be provided by e. the building is used as a public building, where natural means (e.g. an openable window) or previously it was not; mechanical means (e.g. a fan). 37 Building Regulations 2010 Approved Document F Volume 1, 2021 edition O N L I N E V E R S I O N