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

O N L I N E V E R S I O N R24-27C Table 1.1 Summary of notional dwelling specification for new dwelling(1) Element or system Reference value for target setting Opening areas (windows, roof windows, Same as for actual dwelling not exceeding a total area of openings of 25% rooflights and doors) of total floor area(2) External walls including semi-exposed U = 0.18 W/(m²·K) walls Party walls U = 0 Floors U = 0.13 W/(m²·K) Roofs U = 0.11 W/(m²·K) Opaque door (less than 30% glazed area) U = 1.0 W/(m²·K) Semi-glazed door (30–60% glazed area) U = 1.0 W/(m²·K) Windows and glazed doors with U = 1.2 W/(m²·K) greater than 60% glazed area Frame factor = 0.7 Roof windows U = 1.2 W/(m²·K), when in vertical position (for correction due to angle, see specification in SAP 10 Appendix R) Rooflights U = 1.7 W/(m2·K), when in horizontal position (for correction due to angle, see specification in SAP 10 Appendix R) Ventilation system Natural ventilation with intermittent extract fans Air permeability 5 m³/(h·m²) at 50 Pa Main heating fuel (space and water) Mains gas Heating system Boiler and radiators Central heating pump 2013 or later, in heated space Design flow temperature = 55 °C Boiler Efficiency, SEDBUK 2009 = 89.5% Heating system controls Boiler interlock, ErP Class V Either: – single storey dwelling in which the living area is greater than 70% of the total floor area: programmer and room thermostat – any other dwelling: time and temperature zone control, thermostatic radiator valves Hot water system Heated by boiler (regular or combi as above) Separate time control for space and water heating Wastewater heat recovery (WWHR) All showers connected to WWHR, including showers over baths Instantaneous WWHR with 36% recovery efficiency utilisation of 0.98 Hot water cylinder If cylinder, declared loss factor = 0.85 ´ (0.2 + 0.051 V2/3) kWh/day where V is the volume of the cylinder in litres Lighting Fixed lighting capacity (lm) = 185 ´ total floor area Efficacy of all fixed lighting = 80 lm/W Air conditioning None Photovoltaic (PV) system For houses: kWp = 40% of ground floor area, including unheated spaces / 6.5 For flats: kWp = 40% of dwelling floor area / (6.5 ´ number of storeys in block) System facing south-east or south-west NOTE: 1. For a dwelling connected to an existing district heat network, an alternative notional building is used. See paragraph 1.8 and SAP 10. 2. See SAP 10 for details. 12 Approved Document L Volume 1, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N