Guide to Conversion of Traditional Buildings

6.11 Heating and hot water – direct emission heating system

Mandatory Standard

Standard 6.11

Every building must be designed and constructed in such a way that the

means by which space within the building is heated or cooled and by which

hot water is made available in the building is not by means of a direct

emission heating system.

Limitation:

This standard does not apply to:

a) alterations to, or extension of, a pre-2024 building,

b) emergency heating,

c) heating provided solely for the purpose of frost protection,

d) a bioenergy or peat heating system,

e) secondary heating.

6.11.1 Application of standard to conversions

In the case of conversions, as specified in regulation 4, the building as converted shall meet the requirement of this standard (regulation 12, schedule 6).

However, the conversion of a pre-April 2024 building must meet this

standard only:

a. if the conversion involves a change in occupation or use of the part of the

building in which an existing direct emission heating system is located, and

b. in so far as it is reasonably practicable to do so.

6.11.2 Commentary

This standard prohibits the use of ‘direct emissions heating systems’ (DEHS) to help deliver progress towards Scottish Government’s 2045 net zero target, laid out in the Climate Change (Scotland) Act 2009. As of April 2024, all new buildings will be required to use ‘zero direct emission heating systems’ (ZDEHS), the definitions of which, and the underlying regulatory landscape is discussed in Clauses 6.11.0 and 6.11.1.

Clause 6.11.3 of the Technical Handbook goes into more detail about conversions and how the two above-noted exceptions apply. Examples of situations where the second exception would apply include where the work was only the conversion of roof space or an attached garage, neither of which would include the area of the building where the heat source was located.

The clause gives further guidance on how ‘reasonably practicable’ is applied and notes that it is the responsibility of the applicant to demonstrate to the verifier that the installation of a ZDEHS is not reasonably practicable. The following criteria are noted:

a. If the building, pre-conversion, has no DEHS then it is reasonably practicable to maintain this.

b. The cost of a new installation is not considered, except to the extent that replacement would remove the benefit of previous expenditure. Existing systems that comply with section 6.3 as noted in the 2015 Domestic Building Services Compliance Guide or later would be deemed unreasonable to replace.

c. Where there is written evidence from a chartered construction professional specialising in heating systems that it is not technically feasible to install any type of zero direct emission heating system, this would likely be accepted but a significant level of evidence would be likely to be required.

d. In the case of a conversion of a building which has listed status due to its special architectural or historic interest, replacement may be deemed as being not reasonably practicable where the relevant statutory body confirms that the impact on the building’s character would be sufficiently adverse. Historic Environment Scotland’s Guide to Energy Retrofit of Traditional Buildings (2021) is referenced as a potential support in reaching a discussion in these cases.

Clause 6.11.3 concludes by noting that where the installation of a ZDEHS is not carried out, developers should be aware that there is potential for a future requirement to install such a system before 2045, and accordingly, it may be more cost-effective to install such a system as part of any current conversion works.

6.11.3 Issues to be considered

In so far as this section applies, the issues to be considered would be as discussed in the relevant parts of sections 6.3 through to section 6.10.

6.11.4 Recommendations to meet the standard

Recommendations to meet this standard would be discussed in section 6.3 to 6.10 inclusive.