BSI publishes new standard for domestic dwelling retrofit assessments
The British Standards Institution (BSI) has published a new standard, Retrofit Assessment for Domestic Dwellings – Code of Practice (BS 40104:2025). The standard establishes a comprehensive methodology for assessing domestic properties before retrofit works, covering context and condition assessments, ventilation and occupancy evaluations, and energy performance analysis. It introduces competency requirements for professionals conducting assessments and sets out requirements for significance assessment, reporting, and lodgement to ensure thorough documentation and compliance. The standard uses a seven-stage, risk-based whole-house approach intended to balance energy efficiency with occupant well-being and heritage conservation where applicable. The framework aims to standardise processes across the retrofit sector, addressing nearly 19 million UK homes requiring energy efficiency upgrades, and aligns with government efforts to reduce carbon impact while supporting housing supply objectives.