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

O N L I N E V E R S I O N A Appendix A: Key terms NOTE: Except for the items marked * (which generation through automatic controls and by are from the Building Regulations 2010), these facilitating the manual management of those building definitions apply only to Approved Document L, systems. Volume 1: Dwellings. Building control body A local authority building Air barrier An air barrier controls air leakage into control department or an approved inspector. and out of the building envelope. This is usually in *Building envelope (in relation to a building) the form of a membrane. Defined in regulation 35 as the walls, floor, roof, Air permeability The measure of airtightness of windows, doors, roof windows and rooflights. the building fabric. It is defined as the air leakage Centre pane U-value The U-value determined rate per hour per m2 of envelope area at the test in the central area of the glazing unit, making no reference pressure differential of 50Pa or 4Pa. allowance for edge spacers or the window frame. • The limiting air permeability is the worst *Change to energy status Defined in regulation allowable air permeability. 2(1) as any change which results in a building • The design air permeability is the target value becoming a building to which the energy efficiency set at the design stage. requirements of these Regulations apply, where previously it was not. • The assessed air permeability is the value used in establishing the building emission rate and Circuit-watt Refers to the power consumed in the building primary energy rate. The assessed lighting circuits by lamps and, where applicable, air permeability is based on a measurement of their associated control gear (including transformers the air permeability of the building concerned. and drivers) and power factor correction equipment. Airtightness The resistance of the building envelope to infiltration when ventilators are closed. The greater Coefficient of performance (COP) A measure of the the airtightness at a given pressure difference across efficiency of a heat pump at specified source and the envelope, the lower the infiltration. sink temperatures, measured using the procedures in BS EN 14511-2. Automation A control function which automatically adjusts time and temperature settings based on • Heating COP = heat output / power input. occupancy detection and/or stored data from user • % COP (COP � 100) is the heat generator adjustments over time. efficiency. Benchmark Commissioning Checklist A checklist Commissioning When, after all or part of a fixed that can be used to show that commissioning building service or on-site electricity generation has been carried out satisfactorily. (Benchmark is system has been installed, replaced or altered, the registered as a European Collective Mark by the system is taken from a state of static completion to Heating and Hot Water Industry Council, and the working order. Testing and adjusting are carried out content is copyright.) for fixed building services, as necessary, to ensure Building automation and control system A system that the whole system uses no more fuel and power comprising all products, software and engineering than is reasonable in the circumstances. Testing services that can support energy efficient, economical and adjusting are carried out for on-site electricity and safe operation of heating, ventilation and air generation systems, as necessary, to ensure that the conditioning systems and on-site electricity whole system produces the maximum amount of electricity that is reasonable in the circumstances. 72 Approved Document L Volume 1, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N