Building Regulations: Changes to overheating requirements in 2022

Starting June 2022, a number of changes to building guidelines came into force. Intended to help the UK to meet its net zero target, they concern aspects like energy efficiency, ventilation, and overheating.

Part O of the new regulations focuses on protecting the health and welfare of residents by reducing high indoor temperatures. The building must be designed and constructed to:

1. Limit unwanted solar gains in summer.
2. Provide an adequate means of removing excess heat from the indoor environment.

One of two methods can be used to meet this requirement: the simplified method or the dynamic thermal modelling method.

At Broadview, we know the importance of keeping up to date on the latest building regulations. In this post, we explain the difference between the two methods, and how you can go about meeting their requirements with the help of our bespoke roller blinds and awnings.

If you would like to speak to one of our shading specialists for more information, do not hesitate to get in touch.

The Simplified Method

For the simplified method, how to reduce the risk of overheating depends on the location of the new residential building and whether it has cross-ventilation. The building’s overheating risk category is determined by its location in one of the following areas:

1. ‘Moderate risk’ location - England, excluding high risk parts of London.
2. ‘High risk’ location - urban and some suburban parts of London.

To limit solar gains, all of the following standards should be followed:

1. Provide effective shading for buildings in the high risk location.
2. Do not exceed the maximum glazing area percentages.
3. Do not exceed the maximum glazing area percentages of the most glazed room.

To see the specific percentages, view Table 1.1 and Table 1.2 in the full Part O document.

Residential buildings in high risk locations must provide shading for glazed areas between compass points north-east and north-west via the south. Shading should be provided by one of the following means:

1. External shutters with means of ventilation.
2. Glazing with a maximum g-value of 0.4 and a minimum light transmittance of 0.7.
3. Overhangs with 50 degrees altitude cut-off on due south-facing façades only.

The Dynamic Thermal Modelling Method

This method uses dynamic thermal modelling to predict the overheating risk for residential homes.

Using weather data and building characteristics, dynamic thermal modelling predicts the internal conditions and energy demands of a building at short time intervals. It may offer more design flexibility than the simplified method in the following situations:

1. Residential buildings with very high levels of insulation and airtightness.
2. Residential buildings with specific site conditions that mean the building is not well represented by the two risk categories mentioned above.
3. Residential buildings that are highly shaded by neighbouring properties, structures or landscape.

Using this method, solar gains in summer should be limited by any of these means:

Fixed shading devices, comprising any of the following:

• Shutters
• External blinds
• Overhangs
• Awnings

Glazing design, involving any of the following solutions:

• Size
• Orientation
• G-value

Depth of the window reveal.
Building design – for example, the placement of balconies.
Shading provided by adjacent permanent buildings, structures or landscaping.

Excess heat should be removed from the residential building by any of the following means:

1. Opening windows (the effectiveness of this method is improved by cross-ventilation).
2. Ventilation louvres in external walls.
3. A mechanical ventilation system.
4. A mechanical cooling system

For a more detailed look at the new regulations, read through the Approved Documents on the UK government’s website.

Get a Quote on Shading Solutions

Make sure your building is adhering to these new overheating guidelines with Broadview’s external shading solutions. The high-coverage roller screens and awnings we install are fully regulation compliant, helping keep your new building cool throughout the summer.

Get a quote on our shading solutions online or by calling us on 01202 806200!