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

O N L I N E V E R S I O N D Appendix D: Specification for a home built with a heat pump D1 This appendix provides a good practice specification for a dwelling built with a heat pump. D2 By using this specification, the dwelling should pass the target primary energy rate and target emission rate. However, this should be checked through energy calculations. Table D1 S ummary of notional dwelling specification for new dwellings Element or system Reference value for target setting(1) 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 electricity Heating system Air source heat pump and radiators Design flow temperature = 45°C Heat pump(3) Space heating efficiency = 250% Water heating efficiency = 250% Heating system controls Weather compensation Either: – single storey dwelling in which the living area is greater than 70% of total floor area: programmer and room thermostat – any other dwelling: time and temperature zone control, thermostatic radiator valves 84 Approved Document L Volume 1, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N