Overheating Assessments: Part O and TM59

Which Overheating Assessment Do You Need?

Every new house, flat, care home and student residence in England needs an overheating assessment under Part O of the Building Regulations. There are two routes. We check which one fits your design before we start, so you do not pay for two reports.

Part O simplified method

The quickest and cheapest route. It checks the glazed area and the window openings of each home against set limits. From £150+VAT per home.

TM59 dynamic assessment

A dynamic thermal model of your building, run hour by hour against summer weather data. It is the route for heavily glazed or single-aspect homes, blocks of flats with communal heating, sites where windows cannot be left open at night, and major planning applications in London. From £500+VAT.

Commercial buildings: TM52

For offices, schools and other non-domestic buildings we carry out overheating assessments to CIBSE TM52. The details are on the TM59 page.

If the design does not pass

We tell you what to change: smaller or different glazing, shading, or more opening area. If the simplified method will not work, the next step is a dynamic model.

We can run the SAP calculations and the Part G water calculation from the same drawings.

Email your drawings or WhatsApp us for a quote.