This Section:
Proposed Changes to Part L 2010
Changes to the 2006 Criterion
Upper limits are set for elemental u values and air permeability rates, which remain unchanged as Part of L1 2010. The emphasis instead is on reducing the heat loss via Party Walls, improved thermal bridging and better system efficiency improvements.
There are now new standards that apply to heat pumps and various kinds of renewable energy systems.
It is proposed that the Regulations include renewable energy generation equipment, power distribution systems and natural ventilation components. The proposed ADL1A 2010 wording is also more flexible than in 2006 in order not to inhibit innovation. If the type of appliance were not covered by the Domestic Building services Design Compliance Guide, then reasonable provision would be to demonstrate that the proposed system is not less efficient than a comparable system that is covered by the guide. The guide would also include micro generation of heat and electricity by heat pumps, solar thermal panels, CHP, wind turbines and PV.
This criterion was introduced in 2006 to reduce the need for air conditioning and reduce the installed capacity of any air conditioning system that is installed.
For dwellings, there is a calculation as part of SAP, which assesses the risk of overheating. The proposed new Part L1A clarifies that even if the dwelling has cooling installed, this calculation must still be carried out but the cooling system is ignored but with an appropriate assumption about effective air change rate through the open able windows. There was a similar requirement in ADL1A 2006 but it was less important then as there was no option available to model air conditioning systems.
For non-dwellings a completely new approach is proposed: the solar gains through glazing must be less than the solar gains through glazing for a reference building. For side lit buildings, the reference building is 40% glazed, with a 10% frame factor and windows with a solar transmittance factor of 0.46. This calculation would have to be carried out regardless of whether the building has air conditioning or not.
Changes to the 2006 Criterion