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

O N L I N E V E R S I O N L1(b), L2 Comfort cooling 6.49 The specification of comfort cooling systems should be based on a heat gain calculation for the dwelling. To calculate heat gain, both CIBSE’s Guide A and the manufacturer’s guidance should be followed. Systems should not be significantly oversized – in most circumstances, the cooling appliance should not be sized for more than 120% of the design cooling load. 6.50 The seasonal energy efficiency ratio of an air conditioner working in cooling mode should be a minimum of 4.0. 6.51 Comfort cooling systems should have both of the following controls. a. For each control zone and for each terminal unit, independent control of both of the following should be possible. i. Timing. ii. Temperature. b. If both heating and cooling are provided in the same space, the controls should prevent them from operating simultaneously. 6.52 For cooling systems that serve multiple dwellings, follow the guidance in Approved Document L, Volume 2: Buildings other than dwellings. 6.53 Exposed refrigeration pipework should be both of the following. a. Insulated. b. Enclosed in protective trunking. Mechanical ventilation 6.54 Ventilation systems should meet the ventilation needs of the dwelling, in accordance with Approved Document F, Volume 1: Dwellings. Systems should be designed so that they can be commissioned to suitable ventilation rates so that spaces are not significantly overventilated. 6.55 The specific fan power for mechanical ventilation systems should not exceed the following. a. For intermittent extract ventilation systems: 0.5W/(l·s). b. For continuous mechanical extract ventilation systems: 0.7W/(l·s). c. For continuous supply ventilation systems: 0.5W/(l·s). d. For continuous mechanical supply and extract ventilation systems: 1.5W/(l·s). 6.56 All ventilation systems which provide both supply and extract ventilation within the same unit should be fitted with all of the following. a. A heat recovery system with a minimum efficiency of 73%. b. A summer bypass facility (giving the ability to bypass the heat exchanger or to control its heat recovery performance). c. A variable speed controller. Building Regulations 2010 Approved Document L Volume 1, 2021 edition 49 O N L I N E V E R S I O N