Publication - Research and analysis

Building regulations - new domestic buildings: identification and assessment of energy standard improvements

Published: 24 July 2026
Directorate: Local Government and Housing Directorate
Topic: Building, planning and design, Energy
ISBN: 9781836913122

Technical analysis to consider the implications of modelling method, dwelling specification and heating technology up key regulated metrics and costs to both the developer and occupier, to represent the emerging building stock in Scotland.

Part of

Building standards: research

Supporting documents

3. Archetype Information

The archetypes used for this study have been sourced from the UK Building Safety Regulator (BSR), who have undertaken similar technical modelling. These archetypes are evolutions from the original Zero Carbon Hub archetypes used for previous Scottish building regulation updates. To ensure that these are representative dwellings for Scottish new build housing, AECOM has assessed these archetypes against various UK and Scottish Government standards/regulatory requirements.

Firstly, the archetypes were assessed against the Nationally Described Space Standards (NDSS) and scaled to meet the minimum allowable total floor area (TFA) for the number of storeys and bedrooms. Secondly the window designs were assessed against Section 3.28 & 3.14 requirements for maximum glazing area and minimum openable area respectively. Windows were altered to ensure that all regulatory requirements were met. The resulting dwelling information has been outlined in Table 1 below.

Table 1. Final archetype characteristics
Metric	Detached House	End-Terrace House	Mid-Terrace House	Large Flat**	Small Flat**
TFA [m²]	118	93	93	70	50
Sheltered sides	0	1	2	2	3
No. Storeys	2	2	2	1	1
Ground Floor Area [m²]	59.5	46.5	46.5	70.3	50.0
No. Bedrooms	3	3	3	2	1
No. Wet rooms*	3	3	3	2	1
Glazing area ratio to TFA	16.9%	9.6%	9.6%	15.9%	13.9%
Opening area ratio to TFA	13.3%	8.6%	8.6%	7.2%	7.2%

* excluding kitchen

** assumed to be arranged in a block of 16 dwellings (4 storeys (1 ground floor, 2 mid floor, 1 top floor), 4 dwellings per core, 2 large flats and 2 small flats per storey)

To demonstrate the validity of using the above archetypes to represent the new build domestic building stock from 2025 onwards, a comparison against the new build EPC register, from Q1 2021 to Q4 2023, was undertaken. This analysis demonstrated how the proposed modelling sample covers the range of archetypes and sizes of the new build stock in Scotland. The dataset has been presented in Figure 1, Figure 2 and Table 2 below.

Table 2. Average and most common dwelling sizes per archetype
Total Floor Area (TFA)	Detached House	End-Terrace House	Mid-Terrace House	Flat	Bungalow
Dataset Mode [m²]	115	85	85	65	85
Dataset Mean [m²]	145	93	93	65	88
Proposed archetype [m²]	118	93	93	60	N/A

Source: Scottish EPC register [Q1 2021 - Q4 2023]

The BSR supplied archetypes, with AECOM’s revisions to meet relevant regulatory requirements and standards have been observed to well represent the Scottish new domestic building stock, if the development mix from Q1 2021 to Q4 2023 does not significantly alter before 2025. As such, it is concluded that the archetypes are valid for the purpose of testing notional performance specification impacts.

The frequency of flats, houses, bungalows and maisonettes are shown, divided into the following categories: mid-terrace, end-terrace, semi-detached and detached. Detached house is the most frequent dwelling type. — Figure 1. New domestic buildings by dwelling type sourced from Scottish EPC register [Q1 2021 – Q4 2023]

The frequency of each dwelling type is plotted against total floor area (m2). Most dwelling types peak in frequency around a TFA of 85 m2 whilst the detached house is more variable in TFA. — Figure 2. New domestic buildings distribution by TFA and dwelling type sourced from Scottish EPC register [Q1 2021 – Q4 2023]

Contact

Email: buildingstandards@gov.scot

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