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 The new LPG boiler has both lower CO emissions and primary energy than the oil-fired boiler being 2 replaced, and therefore complies. It is also at least as efficient as the minimum efficiency as set out in Section 6 of this guidance. NOTE: If the efficiency of the appliance being replaced is not known, the Standard Assessment Procedure, Tables 4a and 4b, should be used but with no adjustments from Tables 4c and 4d. CO emission factors and primary energy factors should be taken from the Standard Assessment 2 Procedure Table 12. NOTE: Where a heat pump is installed which meets the minimum efficiency standards in this approved document, it should be deemed to be compliant with paragraph 5.4, without the need to carry out this calculation. 5.5 Where a replacement fixed building service involves a fuel-switch in a home with very low heat loss a higher primary energy for the new heating appliance may be acceptable. For example, replacing a gas boiler with direct electric heaters as part of a deep retrofit project, where the resulting heat loss of the dwelling is less than 25kWh/m2 per year. 5.6 If renewable technology such as a wind turbine or photovoltaic array is replaced, the new system should have an electrical output that is at least the same as that of the original installation. 5.7 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 local district heat network). Sizing heating and hot water systems Sizing space heating systems 5.8 The specification of space heating systems should be based on both of the following. a. An appropriate heat loss calculation for the dwelling. b. A sizing methodology that takes account of the properties of the dwelling, such as the Chartered Institute of Plumbing and Heating Engineering’s Plumbing Engineering Services Design Guide. Systems should not be significantly oversized. 5.9 Where a gas combination boiler is used, the boiler type should be selected to modulate down to the typical heating load of the dwelling. 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 dwelling, at a maximum flow temperature of 55°C or lower. 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 dwelling. 36 Approved Document L Volume 1, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N