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JUNE 2022

After 11 years, the Building Research Establishment (“BRE”) has updated the guidelines on site layout and planning for daylight and sunlight. 
The new 2022 edition was published in June this year and has superseded the previous 2011 version.

The key updates are as follows:

The assessment on existing buildings is largely the same, although the guidelines has now been extended to include:

  • Potential increase in overshadowing to areas of recreational water, such as marinas, boating docks, lakes, rivers, streams and canals;

  • Potential loss of energy to solar panels – it is now possible to assess infrared and ultraviolent radiation in Watts to understand how much energy a solar panel is likely to be able to produce.

  • In relation to new dwellings, there have been a number of significant changes, including:

    • Withdrawal of the ‘Average Daylight Factor’ (ADF) methodology for assessing internal daylight – this methodology has been used by designers, consultants and planning officials for over 30 years

    • The ADF methodology has been replaced with two methodologies, of which only one is needed to be used for assessing daylight quality in new dwellings.  These are:

      • Daylight Autonomy (or ‘Illuminance’) – this methodology takes into account climatic data that has been collated since the 1980’s to provide the average levels of illuminance received from the sky across a calendar year.  The assessment also takes into consideration the reflectance of internal and external surfaces.  Quality of daylight amenity is therefore now more reliant of the orientation of a dwelling, whereas previously the ADF test simply assumed a consistent level of brightness equivalent to a predominantly overcast day

      • Daylight factor (or ‘Radiance’) – this methodology, like ADF, uses an overcast sky rather than climatic data.  It does not factor in the contribution of the sun to the brightness of the sky; it is therefore not reliant on orientation such as the Daylight Autonomy method.  Internal and external reflectance levels are also taken into account

    • Assessments of sunlight potential in new dwellings now advises us to check whether at least one main room can receive more than 1.5 hours of direct sunlight on the Spring Equinox (21 March).  Previously sunlight potential in new dwellings was assessed using the ‘Annual Probable Sunlight Hours’ (APSH) test, although unlike ADF, the APSH test has not been withdrawn and is still of relevance

    • ‘View out’ analysis – this is more relevant for assessing new buildings such as schools, where there are areas in the room that a person may be sat for long periods of time.  This assessment simply looks at the ‘view’ from an area within a room, and is not directly linked to daylight/sunlight

    • ‘Solar Convergence’ – solar convergence can occur where new proposals contain a concave element that has the potential to magnify the rays of the sun and subsequently increase the heat of surfaces which the rays reflect to – you may be aware of the overheating issues concerned with the ‘Walkie Talkie’ building, where as a result of solar convergence, the reflected rays caused parts of cars to melt in central London


These changes will have a knock-on effect to how we advise clients and design teams on any planning risks associated with daylight and sunlight.  If you would like to discuss how this may impact current and future proposals, we would be delighted to provide a CPD training session with you and your team.


If this would be of interest, please contact our secretary Erika at or by phone 020 3154 2691 (from 27 June) to arrange a meeting with one of directorship team:


Paul Smith, Director

Ian Smith, Director

Matt Hensey, Associate Director  

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