Ventilation: Approved Document F, Volume 1 — Dwellings

F1(1) O N L I N E V E R S I O N Purge ventilation 1.59 For purge ventilation, follow paragraphs 1.26 to 1.31. Continuous mechanical extract ventilation 1.60 A continuous mechanical extract ventilation system could consist of one of the following. a. A central extract system. b. Individual room extract fans. c. A combination of a central extract system and individual room extract fans. 1.61 If an exhaust air terminal is located on a façade that is exposed to the prevailing wind, measures should be taken to minimise likely wind effects. Solutions could include the following. a. Ducting to another façade. b. Use of constant volume flow rate units. c. Seeking expert advice. Ventilation rates 1.62 The total combined rate of continuous mechanical extract ventilation in the dwelling should be at least the whole dwelling ventilation rate in Table 1.3. 1.63 Each wet room should have a minimum continuous mechanical extract ventilation high rate as given in Table 1.2. Background ventilators for continuous mechanical extract ventilation 1.64 Where continuous mechanical extract ventilation is used, background ventilators should satisfy all of the following conditions. a. Not be in wet rooms. b. Provide a minimum equivalent area of 4000mm2 for each habitable room in the dwelling. c. Provide a minimum total number of ventilators that is the same as the number of bedrooms plus two ventilators (i.e. a one-bedroom dwelling should have three background ventilators, a two- bedroom dwelling should have four background ventilators, etc.). 1.65 If a habitable room has no external walls, paragraphs 1.42 to 1.44 should be followed. Purge ventilation 1.66 For purge ventilation, follow paragraphs 1.26 to 1.31. Mechanical ventilation with heat recovery Ventilation rates 1.67 For dwellings using mechanical ventilation with heat recovery, each habitable room should have mechanical supply ventilation. The total supply air flow should be distributed proportionately to the volume of each habitable room. 1.68 Mechanical supply terminals should be located and directed to avoid draughts. 1.69 The minimum total continuous rate of mechanical ventilation with heat recovery is the whole dwelling ventilation rate in Table 1.3. 16 Approved Document F Volume 1, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N