Conservation of fuel and power: Approved Document L, Volume 1 — Dwellings

O N L I N E V E R S I O N L1(b), L2 a. Dwellings with very low heat demand (e.g. less than 10W/m2). b. Dwelling with buffer zones for heat absorption or dissipation with high thermal mass. 5.21 It may be justified to control a heating zone rather than individual rooms in either of the following cases. a. In single-storey open-plan dwellings in which the living area is greater than 70% of the total floor area. In such cases, the dwelling should be considered as a single heating zone. b. Where two adjacent rooms have a similar function and heating requirements (e.g. kitchen and utility room). In such cases, the adjacent rooms should be considered as a single heating zone. NOTE: Exhaust air heat pump systems, which extract heat from the exhaust air of a dwelling, may not need to provide independent thermostatic control to individual rooms. Providing room/ zone control on this type of system is unlikely to be economically and/or technically viable. However, other space heating systems also in use in the same dwelling should be controlled using thermostatic room controls as described above. NOTE: Commissioning heating systems is covered in Section 8. 5.22 The standards in paragraphs 5.20 and 5.21 may be satisfied by providing any of the following. a. Both of the following. i. A thermostat in a room that the heating circuit serves. ii. An individual thermostatic room control for each heat emitter, such as a thermostatic radiator valve, on all heat emitters outside the room that contains the thermostat. Thermostatic radiator valves should not be used in the same room as the thermostat. b. An individual room/heating zone thermostat or fan coil thermostat for each room or heating zone. c. An individual networked heat emitter control for each emitter. Controls in existing heating and domestic hot water systems 5.23 In addition to paragraphs 5.20 to 5.22, work on existing systems should incorporate the controls detailed in paragraphs 5.24 to 5.27. 5.24 If domestic hot water and space heating are controlled by a single time controller in the existing system, then these may continue to be controlled together after the work is complete. Otherwise, domestic hot water and space heating should each have separate time controls. 5.25 If work is carried out on a system that includes a boiler, a boiler interlock should be installed. 5.26 If replacing a hot water cylinder, the replacement cylinder should have an electronic temperature control, such as a cylinder thermostat. 5.27 If replacing a boiler, the boiler controls should meet the standards in Section 6 for the relevant wet heating system. (The boiler controls are considered to be part of the boiler installation.) 38 Approved Document L Volume 1, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N