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 Special considerations when calculating the dwelling primary energy rate and dwelling emission rate Secondary heating in the dwelling primary energy rate and dwelling emission rate calculation 2.8 When calculating the dwelling primary energy rate and dwelling emission rate for a dwelling with a secondary heating appliance, all of the following apply. a. The value used in the calculation for the fraction of heat provided by the secondary heating system must be as defined by the Standard Assessment Procedure for the particular combination of main heating system and secondary heating appliance. b. The efficiency of the secondary heating appliance with its appropriate fuel should be used in the calculation of the dwelling primary energy rate and dwelling emission rate. c. If a chimney or flue is provided but no appliance is installed, the following appliances should be assumed when calculating the dwelling primary energy rate and dwelling emission rate. i. If a gas point is located next to the hearth, assume a decorative fuel-effect gas fire open to the chimney or flue with an efficiency of 20%. ii. If there is no gas point, assume one of the following: • if the dwelling is not in a smoke control area, an open fire, in a grate, burning multi-fuel with an efficiency of 37% • if the dwelling is in a smoke control area, an open fire, in a grate, burning smokeless solid mineral fuel with an efficiency of 37%. Community heating systems and district heat networks 2.9 If thermal energy is supplied from a district heat network, a CO emission factor and primary 2 energy factor for the heat delivered to the dwelling by the district heat network should be calculated. These factors should be used in the calculations of the dwelling primary energy rate and dwelling emission rate. 2.10 The same CO emission factors used to calculate the dwelling emission rate should be used 2 to check against the minimum performance standards described in Section 6 of this approved document. 2.11 When calculating the dwelling primary energy rate and dwelling emission rate for a dwelling connected to a community heating system or district heat network, the following should all apply. a. The annual percentage of heat supplied from each heat source should be the same for each newly connected dwelling. b. The calculation should account for the predicted effect of all dwellings that will be connected to the system in the first 12 months after the dwellings are connected. c. A submission to the building control body should be made to show that the community heating system or district heat network has the capacity to provide the percentage of heat that is assumed. Building Regulations 2010 Approved Document L Volume 1, 2021 edition 15 O N L I N E V E R S I O N