Approved Document L is split into two volumes; Volume 1 covers dwellings; Volume 2 covers buildings other than dwellings.

Approved Document L Volume 1 applies to dwellings only and contains current and future guidance covering the energy efficiency requirements as set out in Part L of Schedule 1 to the Building Regulations and in a number of specific building regulations.

Guidance provided includes information about limiting heat gains and losses, air permeability and pressure testing, insulation regulations, boiler productivity, lighting, and storage techniques for hot water. Further information covered includes fixed standards for Carbon Index ratings, solar emissions, heating and ventilation systems, space heating controls and air conditioning systems, amongst other fuel and power systems. 

Approved Document L Volume 2 applies to buildings other than dwellings It gives guidance on how to comply with Part L of Schedule 1 to the Building Regulations and the energy efficiency requirements for buildings other than dwellings.

Guidance provided includes insulation regulations, boiler productivity, lighting, and storage techniques for hot water. Further information covered includes fixed standards for Carbon Index ratings, solar emissions, heating and ventilation systems, space heating controls and air conditioning systems, amongst other fuel and power systems.