Part L is one of many Building Regulations that your house will have to meet on completion. Part L relates to heating and hot water. This is a very detailed document that your builder, plumber, heating designer will have to follow to meet the minimum requirements and to make sure your heating system is up to building regulations.
The Part L document of current building regulations sets out maximum energy usage and carbon emission levels for the dwellings. It also states that all new buildings must incorporate some form of renewable energy technology to help reduce the use of fossil fuels to heat the dwelling or to reduce the primary electricity usage. The most popular renewable energy sources used are heat pumps for heating and hot water.