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

O N L I N E V E R S I O N R24-27C Heating in the building primary energy rate and the building emission rate calculations 2.6 When systems are capable of being fired by more than one fuel, the following applies, according to the fuel(s). a. Biomass heating supplemented by an alternative appliance (e.g. gas) – the CO emission factor 2 and primary energy factor should be based on a weighted average for the two fuels. The weighting should be based on the anticipated usage of those fuels. The building emission rate and building primary energy rate submission should be accompanied by a report, signed by a suitably qualified person, detailing how the combined emission factor has been derived. b. Appliances capable of burning both biomass fuel and fossil fuel – the CO emission factor and 2 primary energy factor for dual-fuel appliances should be used, except where the building is in a smoke control area, when the anthracite figure should be used. c. In all other cases, the fuel with the highest CO emission factor should be used. 2 2.7 If thermal energy is supplied from a district heat network or community heating system or community cooling system, CO emission factors and primary energy factors should be determined 2 by considering the details of the scheme and following the guidance in items (a) to (g) below. a. The CO emission factor and primary energy factor for the heat delivered to the building by the 2 district heat network should be based on the ‘heat network’ specific factors from Table 32 in the National Calculation Methodology Modelling Guide. b. Calculations should take account of the annual average performance of the whole system, including the distribution circuits, all heat generating plants, combined heat and power (CHP), and any waste heat recovery or heat dumping. c. The calculation should include the predicted effect of all buildings or parts of buildings that will be connected to the system in the first 12 months of operation. A change in the number of buildings or spaces within buildings connected to the system might affect the percentage of heat supplied from the communal system. The increased operation of any marginal plant (e.g. gas boilers) can then be properly accounted for. d. The electricity generated by any combined heat and power (CHP) or trigeneration scheme should always be credited using the appropriate CO emission and primary energy ‘heat network’ specific 2 factors from Table 32 in the National Calculation Methodology Modelling Guide. e. CO emissions and primary energy associated with the thermal energy streams of a trigeneration 2 scheme should be attributed in proportion to the output energy streams. f. When calculating the building primary energy rate and building emission rate for a building connected to a new district heat network, the calculation should include all heat sources to be used up to 31 December 2027. In this way, any planned transition of the heat network to an alternative means of heat generation will be properly accounted for. When there will be a change in heat source up to 31 December 2027, a submission to the building control body should be made to show both of the following. i. That planning permission, if required, has been granted for the change. ii. That the heat network will connect to the new source, with confirmation in the form of a signed contract to connect and supply heat. NOTE: An existing district heat network is defined in Appendix A. A new district heat network should be taken as meaning any other district heat network. 11 Building Regulations 2010 Approved Document L Volume 2, 2021 edition O N L I N E V E R S I O N