New Build Heat Standard (amended) 2024: business and regulatory impact assessment

9. Potential emissions impacts

31. This addendum to the BRIA prepared for the original NBHS (as introduced on 1 April 2024) also explores the potential emissions impacts from the options considered in the review.

32. Option 1 most closely follows the NBHS as introduced on 1 April 2024, with a minor change to the definition of ‘emergency heating’. We therefore expect projected emissions and savings under this option to remain similar to estimates provided in the original Business and Regulatory Impact Assessment (BRIA) ^[6].

33. Option 2 restricts the NBHS to main systems only, thereby permitting all secondary heating systems. However, it is extremely difficult to estimate emissions associated with secondary heating systems as their use is likely to vary significantly by dwelling, location and behaviour. For example, some people may choose to use secondary heating regularly, while others will only use it on occasion. EPC data^[7] shows that approximately 4% of new homes had secondary heating installed over the last three years (2021 – 2023) – this is around 2,500 of 65,500 new build homes, with over 80% (2,000) of these systems being wood-fired. Installations are proportionately higher in islands postcodes, being present in 28% of new homes – again with wood-fired solutions accounting for over 80% of installations. We would expect similar trends to continue under this option.

34. Based on the above, and to provide a broad illustrative example of the potential increase in emissions (relative to the NBHS as introduced on 1 April 2024), we assume secondary heating is used at about 25% the rate of main heating, with continued installation at a rate of 3% of new builds. This could result in roughly 2 tCO2e per year, or about 480 tCO2e to 2045. This is a negligible amount of emissions accumulated to 2045 as part of overall emissions from buildings (less than 0.0001% of current emissions from buildings).

35. Option 3 permits the installation of all bioenergy and peat heating systems. Using the same EPC data, the total number of new homes that installed bioenergy main heating systems over the three year period 2021-2023 is very low – 84 out of 65,500 completions, representing around 0.1%. For new homes in island postcodes, there were fewer than 10 properties with a bioenergy main heating system out of over approximately 1,200 EPCs^[8].

36. While we do not have emissions data for specific bioenergy heating systems, we do know that in 2022, the Greenhouse Gas Inventory reported 0.08 MtCO2e emissions associated with fireplaces and closed stoves in all residential (domestic) properties^[9] (accounting for 16% of total emissions from residential properties in Scotland). However, given that the number of new build homes built each year as a proportion of all residential properties in Scotland is very low^[10], and further, that we expect the installations of bioenergy heating systems in new build homes to be low again (using above EPC data), the actual increase of emissions from pursuing this Option (relative to the NBHS as introduced on 1 April 2024) is again likely to be negligible.

37. For the non-domestic sector, we know that over the same three-year period, approximately 950 new non-domestic buildings were completed. 12 buildings identified a form of bioenergy as their main heating fuel, whilst a further 11 are listed as ‘other’, which may include other bioenergy sources. Together this amounts to 2.4% of new non-domestic developments. Again, while we do not have emissions data for specific bioenergy heating systems in non-domestic buildings, given the small number of buildings using these systems we expect installation levels to remain very low and the actual increase on emissions relative to the NBHS as introduced to be negligible.