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

DA O N L I N E V E R S I O N Table D2 A dditional energy efficiency measures which should usually be installed whenever consequential improvements apply as a result of: • the provision of a fixed building service in the building for the first time, or • increasing the capacity of any fixed building service These measures are considered technically, functionally and economically feasible in normal circumstances. The extent of these measures should not be based on the value of the principal works, as outlined in Section 12, and should be installed in so far as they are technically, functionally and economically feasible. Item Improvement measure 1 If the installed capacity per unit area of a heating system is increased, both of the following apply. a. Thermal elements within the area served that have U-values higher than those in Table 4.2, column (a), should be replaced or renovated following the guidance in Section 10 or Section 11 of this approved document. b. Existing windows, roof windows or rooflights (but excluding display windows) or doors (but excluding high-usage entrance doors) within the area served should be replaced in line with the guidance in Section 10 if they have U-values higher than: • for windows, roof windows and doors – 3.30W/(m2·K) • for rooflights – 3.80W/(m2·K), calculated by following paragraph 4.4. 2 If the area-weighted installed capacity of a cooling system will be increased, both of the following apply. a. Thermal elements within heated areas served that have U-values higher than those set out in Table 4.2, column (a), should be replaced or renovated following the guidance in Section 10 or Section 11 of this approved document. b. The solar control provisions should be upgraded if either of the following criteria is met. i. The area of windows and roof windows (but excluding display windows) within the area served exceeds 40% of the façade area. ii. Both: • the area of rooflights exceeds 20% of the area of the roof, and • the design solar load exceeds 25W/m2. The upgraded system should meet at least one of the following four criteria. iii. The solar gain per unit floor area averaged over the period 06:30 to 16:30 GMT, and when the building is subject to solar irradiances for July as given in the table of design irradiancies in CIBSE’s Guide A, should not be greater than 25W/m2. iv. The design solar load should be reduced by at least 20%. v. The effective g-value should be no worse than 0.3. vi. The zone or zones should satisfy the solar gain check in paragraphs 4.16 to 4.18. 3 Any general lighting system within the area served by the relevant fixed building service that has an average efficacy of less than 60 light source lumens per circuit-watt should be upgraded with new luminaires and/or controls following the guidance in Section 6. 9966 AApppprroovveedd DDooccuummeenntt LL VVoolluummee 22,, 22002211 eeddiittiioonn BBuuiillddiinngg RReegguullaattiioonnss 22001100 O N L I N E V E R S I O N