Research and analysis

Gathering evidence to improve airtightness in the UK housing stock

This research gathered evidence on the baseline airtightness of the UK housing stock, to support domestic retrofit policy and modelling tools.

• From: Department for Energy Security and Net Zero
• Published: 1 October 2025

Documents

Baseline airtightness of the GB housing stock

Ref: 2025/002

PDF, 1.3 MB, 84 pages

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Evidence to support an update to the methodology for estimating infiltration rates in SAP

Ref: 2025/002

PDF, 1.21 MB, 56 pages

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Airtightness retrofit and construction practices, unintended consequences, and ventilation practices

Ref: 2025/002

PDF, 771 KB, 79 pages

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Project summary and options for future work

Ref: 2025/002

PDF, 436 KB, 37 pages

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Details

Understanding airtightness is important for minimising heat loss through uncontrolled air exchange between the inside and outside of a building, and good airtightness plays an important role in achieving low energy, comfortable homes.

This research was designed to gather evidence on the airtightness of the UK housing stock, and support energy efficiency policy, including the Standard Assessment Procedure (SAP) and the development of its successor the Home Energy Model (HEM).

Published 1 October 2025