Converted flats and the 45kW heat network exemption

A building converted into flats is exempt if it has one energy source of 45kW thermal capacity or less. Purpose-built blocks don't get this exemption.

Who the exemption covers

It applies to existing buildings that have been divided into several homes, such as a Victorian house split into flats, where one energy source serves them all and its capacity is no more than 45kW thermal.

How to check

The rating is on the boiler's data plate, in the installation paperwork, or in the service records your heating contractor keeps. Ask them to confirm it in writing and keep that with the building file.

When the exemption stops applying

• The boiler is replaced with plant larger than 45kW
• A second energy source is added
• The building wasn't a conversion in the first place

If any of these apply, the building is treated like any other communal heat network and must be registered.