Approved Document Part O: Overheating

With recent efforts focusing on improvements to insulation and thermal performance of structures (Part L), British homes face the threat of overheating, especially during the warmer months – something I expect all of us have experienced over the past couple of days.

To tackle this risk, the Government published Approved Document O in December 2021. This accompanied the publication of the 2021 edition of Part L and Part F of the Building Regulations for non-domestic buildings and dwellings.  This took effect on 15th June 2022 and applies to new residential building.

Part O (Overheating) applies to new build homes and buildings where people sleep overnight.

There are two methods to demonstrate compliance.

The simplified method considers area and orientation of glazing and compares this area to the floor area of the structure. Window opening areas are also factored to allow heat to escape from openable windows. Unfortunately, there are drawbacks which will result in failure of this method is used in certain situations.

The other method is dynamic thermal modelling. This method provides a standardised approach to predicting overheating risk for residential buildings.

How can we help?

Timber Frame. We’ve talked previously about how timber frame can help with Part L – conservation of fuel & Power, keeping the heat in. Can it also keep the heat out? Yes. The reflective membranes used in timber frame construction effectively block infrared radiation. The same qualities that help achieve in keeping the heat in during the colder months, air tightness, helps keeps the heat out during the hotter months.

Unlike traditional masonry equivalents, the lightweight structure of timber frame does not absorb heat well, so it cannot contribute to the excessive and uncomfortable night-time temperatures experienced as masonry walls release their stored up daytime heat. In winter, timber frame building’s quick heating response time can be appreciated. Without a heavy energy absorbing internal structure to heat up first, occupants benefit from a fast heating response, on demand, while benefiting from low heating bills too.  

If you’d like to talk to Robinson Manufacturing about Timber Frame solutions to new statutory regulations like Approved Document Part O: Overheating, then email us or call 01933 279597.

If you have a development project you’d like to talk to our timber frame team about, email or call us on 01933 279597.