Question to the Department for Business, Energy and Industrial Strategy:

To ask Her Majesty's Government, further to the Written Answer by Lord Callanan on 16 June (HL4962), what assessment they have made, if any, of the impact on carbon dioxide emissions of fitting all (1) new social housing developments, (2) replacement boilers in social housing, (3) new houses, and (4) replacement boilers in all houses, with stored passive flue gas heat recovery technology in each year to 2025.

Introduced in 2018, Boiler Plus regulations raised standards for all domestic boiler installations, supporting efforts to reduce carbon emissions while making it easier and cheaper to heat homes. In addition to raising the minimum efficiency standards for boilers, the regulations required an additional energy efficiency measure to be installed alongside combination gas boilers that accounted for 78% of the market. The measures include flue gas heat recovery.

Many system boilers and most regular boilers on the market were incompatible with flue gas heat recovery systems and compensation controls when boiler plus regulations were introduced and therefore were exempt from the requirement.

The extent to which a passive flue gas heat recovery system can increase the efficiency of a dwelling and reduce natural gas consumption is dependent on many factors including the annual space heating and domestic hot water demand of the specific building and importantly whether the system installed has built-in thermal storage. However, analysis showed that the typical household could increase boiler efficiency between 1% to 5% by adding a passive flue gas heat recovery system.