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New Homes

With growing awareness that new homes can be at risk of overheating, the Government recently introduced Approved Document Part O (Overheating) to the Building Regulations.

This requires that all new homes have an overheating assessment carried out at the design stage to ensure that unwanted solar gains are limited, and that homes have sufficient ventilation to remove excess heat.

There are two methods of compliance, both of which we can help with:

Simplified method

  • This method compares the proposed design to the maximum glazed areas and minimum free areas for ventilation set out in Part O.

  • This is generally used for houses without excessive areas of glazing, in locations where noise or security concerns don't prevent windows being left open. It doesn't allow for the effect of measures such as window shading to be assessed.

Dynamic thermal modelling 

  • This type of analysis is a much more comprehensive assessment of overheating risk and allows us to investigate in more detail the impact of measures to mitigate overheating risk. These might include window sizes, glazing specification, shading and ventilation.


  • This method is typically used for flats without cross ventilation, properties with ground floor bedrooms and houses with larger glazed areas.

We carry out Overheating assessments in line with the guidance of CIBSE TM59 and Part O, using the latest Design Builder software.

We can help with

Building Regulations

Part O Compliance

Dynamic thermal modelling

CIBSE TM59 analysis

Simplified Calculations

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