In forceVentilation & Overheating

CIBSE TM59 overheating assessment

Design-stage methodology for homes

CIBSE's design-stage methodology for assessing overheating risk in homes using dynamic thermal modelling, referenced by Approved Document O.

Also known as: TM59, CIBSE TM59, overheating assessment

Jurisdiction: UK
Document type: Technical standard
Edition: 2026 edition
Source updated: Not stated by publisher
Applies from: —
Topic: Ventilation & Overheating

Key requirements

Uses dynamic thermal modelling rather than a steady-state calculation.
Defines occupancy profiles and assessment criteria for living areas and bedrooms.
Requires appropriate weather files and modelling assumptions.
The 2026 update reflects current industry practice.
A modelling report should be provided to building control for Part O.

Performance at a glance

Method: Dynamic thermal modelling
Use: Part O compliance

Applies to

New homes and residential buildings in the UK.

Official source

CIBSE — TM59 (2026)

Open official source

Related records

Reviewed 25 October 2026. This summary is an editorial reference, not legal advice. Check the current official text and confirm the approach with building control before relying on it. Browse all 35 records.