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

L1(b), L2 O N L I N E V E R S I O N NOTE: For grid-supplied electricity, a CO emission factor of 0.136kgCO /kWh and primary energy 2 2 factor of 1.501kWh /kWh should be used. All other CO emission factors and primary energy PE 2 factors should be taken from Table 29 (or Table 32 for district heat networks) of the National Calculation Methodology Modelling Guide. NOTE: Where the efficiency of the appliance being replaced is unknown, this should be established in line with the hierarchy outlined in Appendix E. 5.5 If renewable technology such as a wind turbine or photovoltaic array is being replaced, the new system should have an electrical output that is at least the same as that of the original installation. 5.6 When installing a new heating appliance in an existing building, the heating system after the work is complete should have the following controls. a. Timing. b. Temperature. c. Where appropriate and technically feasible, weather compensation. 5.7 For heating systems that are being replaced, paragraphs 5.9 to 5.12 should be followed in addition to system specific guidance in Section 6. Facilitating future connection to any local district heat networks should be considered (e.g. providing capped off connections in pipework to allow later connection to a district heat network). 5.8 If work involves providing or extending fixed building services, energy meters should be installed following paragraph 5.17, and consequential improvements may apply (see Section 12). Sizing new and replacement space heating systems 5.9 The specification of space heating systems should be based on an appropriate heat loss calculation for the building, based on BS EN 12831-1 and CIBSE’s Guide B1. Systems should not be significantly oversized. 5.10 Where a wet heating system is either: a. newly installed b. fully replaced in an existing building, including the heating appliance, emitters and associated pipework all parts of the system, including pipework and emitters, should be sized to allow the space heating system to operate effectively, and in a manner that meets the heating needs of the building, at a maximum flow temperature of 55°C or lower. To maximise the efficiency of these systems, it would be preferable to design to a lower flow temperature than 55°C. Where it is not feasible to install a space heating system that can operate at this temperature (e.g. where there is insufficient space for larger radiators, or the existing distribution system is provided with higher temperature heat from a low carbon district heat network), the space heating system should be designed to the lowest design temperature possible that will still meet the heating needs of the building. 36 Approved Document L Volume 2, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N