Ventilation: Approved Document F, Volume 1 — Dwellings

O N L I N E V E R S I O N F1(1) * The noise index L is used in BS 8233, where T is the duration of the measurement. If the noise from the Aeq,T sound source is steady (i.e. fluctuating by up to 3dB), a measuring time of 1 minute will be adequate and the L level will be similar to the dB(A) level used elsewhere. lf the noise from the sound source fluctuates Aeq, 1 min more than this, a longer measuring time (T) may be required, but the higher portion of the fluctuating level should be considered, and the sound may attract more attention due to the changes in level. NOTE: Methods for measuring the sound power level produced by the fan unit of decentralised extract ventilation, centralised extract ventilation and balanced mechanical ventilation with heat recovery systems are described in BS EN 13141. Access for maintenance 1.8 Reasonable access should be provided for maintaining ventilation systems, including all of the following. a. Providing access to replace filters, fans and coils. b. Providing access points for cleaning ductwork. c. Providing access for the general maintenance of the plant. The ventilation strategy in this approved document 1.9 The ventilation strategy in this approved document relies on a combination of all of the following. a. Extract ventilation from rooms where water vapour or pollutants are likely to be released (e.g. bathrooms and kitchens), to minimise their spread to the rest of the building. Ventilation fans may be either intermittent operation or continuous operation. b. Whole dwelling ventilation to provide fresh air to the building and to dilute, disperse and remove water vapour and pollutants not removed by extract ventilation. c. Purge ventilation to remove high concentrations of pollutants and water vapour. Purge ventilation is used intermittently and required only for pollutants produced by occasional activities (e.g. fumes from painting). 1.10 Ventilation may be delivered through natural ventilation, mechanical ventilation or a combination of both. 1.11 The ventilation systems in this approved document are examples of systems that comply with Part F of the Building Regulations. Other ventilation systems may be acceptable if they can be shown to meet an equal level of performance. Performance-based guidance 1.12 Performance criteria for acceptable levels of moisture and pollutants are given in Appendix B. Ventilation rates designed to meet the performance criteria are given in Tables 1.1 to 1.3. 1.13 Ventilator sizes for the whole dwelling are also provided in Table 1.7 to help designers comply with Part F of the Building Regulations in common situations. 1.14 Some ventilation system designs can, in certain circumstances, result in lower ventilation rates than those stated in Table 1.1 and Table 1.2 (e.g. systems with automatic controls). Where lower ventilation rates are proposed, expert advice should be obtained to demonstrate that the solution meets the performance standards in Appendix B. 7 Building Regulations 2010 Approved Document F Volume 1, 2021 edition O N L I N E V E R S I O N