Use the new building regulations

All previous regulations on overheating have been brought together into the new official Overheating: Approved Document O (also known as ‘Part O’).

It stresses the importance in design of limiting solar gains through windows and providing adequate opening areas to remove excess heat in relation to:

• high risk locations
• moderate risk locations
  
  

It also provides additional guidance on other limiting factors such as:

• noisy roads
• pollution
• security 

Overheating in pipework (particularly in community heating schemes) is covered under Conservation of fuel and power: Approved Document L (also known as ‘Part L’).

Check design decisions as early as possible

It’s critical to check your overheating design decisions at the earliest possible stage. 

Any changes later in the design process (for example, to achieve compliance) may fundamentally alter key aspects such as openings, dwelling orientation and shading features.

This may have implications in other key areas - for example, previously obtained planning permission.

Use passive cooling

You must show local building control how your designs have used all possible passive means to cool a home before you use mechanical cooling. 

Passive cooling must be achieved by limiting solar gains and minimising and removing excess heat through openings.

Find out how to improve ventilation under the new building regulations. 

Limit solar gains

You must limit solar gains within your designs and consider the following:

• appropriate design and orientation 
• attention to glazing areas, shading devices and window reveal depths
• types of glazed areas and window g-values
• fixed shading devices such as awnings, external blinds, overhangs and shutters
• the surrounding environment such as landscape, structures and other buildings

Minimise and remove excess heat

You must find ways to minimise and remove excess heat within your designs and consider:

• using all practical means to avoid mechanical ventilation or cooling systems
• controlling heat loss from pipework - particularly in community heating schemes
• cross-ventilation and ventilation louvres in external walls

Choose a compliance model 

You must use one of the following recognised compliance methods to show your designs meet the new regulations:

• simplified method
• dynamic thermal modelling method
  
  

Find out more in Sections 1 and 2 of Overheating: Approved Document O.

Complete the compliance checklist

Document your compliance with new regulations using the ‘Compliance checklist’ in Appendix B of the official Overheating: Approved Document O.

You must provide local building control with details and show which compliance method you used to meet the new regulations.

The final ‘Part 3’ section of the checklist must be completed by the builder and local building control inspector.

Find out how to provide information for SAP assessors and building control.

Record your design decisions

You must document your decision-making throughout your design process.

Use this documentation to show SAP assessors and local building control your decisions and how your designs meet the new regulations.

Find out how to provide information for SAP assessors and building control.

Provide information for homeowners

You must also provide details for homeowners about how overheating systems are controlled and maintained within their new homes.

Find out how to provide homeowners with information about their new homes.

Keep up to date

Use the Future Homes Hub to keep up to date with changes to the building regulations and the introduction of the Future Homes Standard.

Check what you need to do to meet the new regulations through our detailed guides.

Find out more

Find out more about improving thermal conductivity and air permeability under the new regulations: Improve fabric, airtightness and thermal bridging performance.

Find all new regulations in the official Approved Documents on GOV.UK:

• Conservation of fuel and power: Approved Document L - ‘Part L’
• Overheating: Approved Document O - ‘Part O’
• Ventilation: Approved Document F - ‘Part F’