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

O N L I N E V E R S I O N AA • In the case of a newly constructed conservatory or porch, windows and doors have similar draught-proofing provisions as the exposed windows and doors elsewhere in the dwelling. Total useful floor area The total area of all enclosed spaces, measured to the internal face of the external walls. When calculating total useful floor area, both of the following should be taken into account. • The area of sloping surfaces such as staircases, galleries, raked auditoria and tiered terraces should be taken as their area on plan. • Areas that are not enclosed, such as open floors, covered ways and balconies, should be excluded. NOTE: This area is the gross internal floor area as measured in accordance with the Code of Measuring Practice by the Royal Institution of Chartered Surveyors (RICS). U-value A measure of the ability of a building element or component to conduct heat from a warmer environment to a cooler environment. It is expressed as the quantity of heat (in watts) that will flow through 1m2 of area divided by the difference in temperature (in degrees K) between the internal and external environment. The unit is W/(m2·K). Weather compensation A system which enables the operating flow temperature of a heating system to be varied. An external sensor communicates with one inside the boiler. The temperature is varied by either of the following. • Modulating the heat generator output (direct acting). • Using a mixing valve to adjust the flow temperature to the heat emitters. Wet heating system When a heating appliance (usually a boiler) produces hot water which is distributed around the dwelling to heat emitters. BBuuiillddiinngg RReegguullaattiioonnss 22001100 AApppprroovveedd DDooccuummeenntt LL VVoolluummee 11,, 22002211 eeddiittiioonn 7777 O N L I N E V E R S I O N