The Building Regulations, Part L
L1 -- Conservation of Fuel and Energy
A building shall be designed and constructed to ensure that its energy performance limits the amount of energy required for its operation and the amount of CO2 emissions associated with this energy use, as is reasonably practicable.
L2 -- Conservation in Existing Dwellings
For existing dwellings, L1 requirements shall be met by:
limiting heat loss and, where appropriate, maximising heat gain through the building’s fabric
controlling, as appropriate, the output of the space heating and hot water systems
limiting heat loss from pipes, ducts, and vessels used for the transport or stage of heated water or air
providing that all oil and gas fired boilers installed as replacements in existing dwellings meet a minimum seasonal efficiency of 90% where practicable.
L3 -- Conservation of Fuel and Energy in New Dwellings
For new dwellings, L1 requirements shall be met by:
providing that the dwelling’s energy performance limits the calculated primary energy consumption and related CO2 emissions insofar as is reasonably practicable when both energy consumption and CO2 emissions are calculated using the Dwelling Energy Assessment Procedure (DEAP) published by the Sustainable Energy Authority of Ireland
providing that, for new dwellings, a reasonable proportion of the energy consumption to meet the dwelling’s energy performance is provided by renewable energy sources
limiting heat loss and, where appropriate, availing of heat gain through the building’s fabric
providing and commissioning energy efficient space and water heating systems with efficient heat sources and effective controls
providing that all oil and gas fired boilers shall meet a minimum seasonal efficiency of 90%
providing to the dwelling owner sufficient information about the building, the fixed building services, and their maintenance requirements so that the building can be operated to use no more fuel and energy than is reasonable.
