Conservation of fuel and power: Approved Document L, Volume 2 — Buildings other than dwellings

O N L I N E V E R S I O N L1(b), L2 Table 6.9 M aximum specific fan power (SFP) in air distribution systems in new and existing buildings System type(1) SFP (W/(l·s))(2)(3) New buildings Existing buildings Central balanced mechanical ventilation system with heating and cooling 2.0 2.6 Central balanced mechanical ventilation system with heating only 1.9 2.2 All other central balanced mechanical ventilation systems 1.5 2.0 Zonal supply system where fan is remote from zone, such as ceiling 1.1 1.4 void or roof-mounted units Zonal extract system where fan is remote from zone 0.5 0.5 Zonal balanced supply and extract ventilation units, such as ceiling 2.3 2.3 void or roof units Local balanced supply and extract ventilation system, such as wall/ 2.0 2.0 roof units Local supply or extract ventilation units, such as window/wall/roof 0.3 0.4 units (e.g. toilet extract) Other local ventilation supply or extract units 0.5 0.5 Fan assisted terminal variable air volume (VAV) unit 0.5 0.5 Fan coil unit (rating weighted average(4)) 0.4 0.4 Kitchen extract, fan remote from zone with grease filter 1.0 1.0 NOTES: 1. A central system is one which serves the whole or major areas of the building. A zonal system is one which serves a group of rooms or areas in part of the building and requires ducting. A local system or unit is one which serves a single room or area and does not require ducting. 2. For balanced supply and extract systems, the maximum SFP includes an allowance for heat recovery and return filter. 3. Where any of the following components are included in the installation, the maximum SFP may be increased. a. High-efficiency particulate air (HEPA) filter: add 1.0W/(l·s). b. Humidifier/dehumidifier: add 0.1W/(l·s). c. Active chilled beams: add 0.3W/(l·s). d. Transpired solar collector: add 0.3W/(l·s). For example, a central balanced mechanical ventilation system with heating and cooling, HEPA filter and humidifier, installed in a new building. SFP = 2.0 + 1.0 + 0.1 = 3.1W/(l·s) 4. The rating weighted average is calculated using the following formula: [(P �SFP) + (P � SFP )+(P � SFP )+ ...] mains,1 1 mains,2 2 mains,3 3 (P + P + P +...) mains,1 mains,2 mains,3 where P is useful power supplied from the mains in W. mains 51 Building Regulations 2010 Approved Document L Volume 2, 2021 edition O N L I N E V E R S I O N