To ask Her Majesty's Government, further to the Written Answer by Lord Callanan on 3 August (HL7278), why passive flue gas heat recovery systems with thermal storage are not mandated for (1) all replacement boilers in the UK, and (2) installation in all new buildings; and whether those systems deliver an average five per cent efficiency improvement and significant carbon savings.
Building Regulations set minimum energy performance standards for heating systems in new homes and when they are replaced or fitted into existing homes.
Under these regulations, when a gas combination boiler is installed in an existing dwelling, an additional energy efficiency measure must also be installed, with passive flue gas heat recovery systems being one of four options. The English housing stock is diverse, so the requirement is flexible to allow a suitable choice to be made that reflects the nature of the building, and the needs of the individual household.
When these regulations were introduced, many system and most regular boilers on the market were considered incompatible with passive flue gas heat recovery systems and compensation controls, or required an additional component, and therefore were exempt from the additional energy efficiency measures.
For new builds, buildings regulations around energy efficiency and space and water heating are deliberately couched in performance terms and do not prescribe the technologies, or fuels to be used, allowing manufacturers and builders the flexibility to innovate and select the most practical and cost-effective solutions in particular circumstances.
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. Analysis undertaken on behalf of BEIS showed that the typical household could increase boiler efficiency between 1% to 5% by adding a passive flue gas heat recovery system.