Part O compliance is a newly introduced requirement of the Building regulations (Part O) for new build residential properties. The aim is to reduce the likelihood of occupants of the building experiencing occurrence of high indoor temperatures.

We recommend Part O is considered before planning permission is applied for to reduce the risk of amending approved plans, therefore reducing timescales. There are two methodologies that can be applied:

Simplified Method  

Used to limit solar gains and provide a means of removing excess heat. We will look at the following:

  • Location
  • Building Aspect
  • Window area

Simplified method is quite restrictive and is only recommended for simple buildings where glazing will meet the strict glazing / floor area / orientation limitation set out in the Approved document Part 2021


Our assessors have been using the modelling software for over 15 years so they are very conversant with the process. They will advise on the best approach for your individual situation to ensure full compliance is achieved.

If you would like to know more about how we can help you please get in touch.

Dynamic Simulation Method (TM59)

Provides a standardised approach to predicting overheating risk for residential buildings using dynamic thermal modelling as an alternative to the simplified method.

Building control will be provided a report demonstrating the residential building passes CIBSE’s TM59 assessment of overheating

  • CIBSE’s TM59 methodology for predicting overheating risk
  • Limits on the use of CIBSE’s TM59 methodology
  • Acceptable strategies for reducing overheating risk

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