Dynamic Thermal Analysis for Dwellings
CIBSE Technical Memorandum 59
CIBSE TM59 provides a standardised methodology for predicting overheating risk for residential building designs (new-build or major refurbishment) using Dynamic Thermal Analysis. It is the approved Dynamic Thermal Analysis approach for demonstrating compliance with Building Regulations Part O.
Part O Compliance
Approved Document Part O introduces two routes to demonstrate compliance:
Route 01
Limits solar gains and provides a means of removing excess heat through window sizing or window design.
Learn moreRoute 02
CIBSE TM59 is the approved Dynamic Thermal Analysis approach for Part O — used when simplified method is not suitable or fails.
About CIBSE TM59
The methodology provides a baseline for all domestic overheating risk assessments and also provides a set of profiles that represent reasonable usage patterns for a home suitable for evaluating overheating risk.
CIBSE TM59 is intended for use by designers in order to influence building design for the better. It could be used at the planning stage to assess risk, as well as at later stages of design.
Compliance Criteria
TM59 compliance is based on passing both of the following criteria for all relevant rooms:
Criterion A — Living rooms, kitchens & bedrooms
The number of hours during which the operative temperature exceeds the threshold by ≥1 K during May to September shall not exceed 3% of occupied hours.
Criterion B — Bedrooms only
For bedrooms only: to guarantee comfort during the sleeping hours the operative temperature in the bedroom from 10 pm to 7 am shall not exceed 26 °C for more than 1% of annual hours.
Note: 1% of the annual hours between 22:00 and 07:00 for bedrooms is 32 hours, so 33 or more hours above 26 °C will be recorded as a fail.
Both Criterion A and B must be passed for all relevant rooms. Failure of either in any room means the dwelling fails TM59 compliance.
We can assist you with Building Regulations Part O compliance and any other overheating risk analysis requirements using dynamic thermal simulation software to model and assess your project accurately.
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