Expert answers to the top 10 FAQs on Daylight and Sunlight Assessments

This blog provides answers to the top 10 FAQs for daylight and sunlight assessments. As the criteria for daylight and sunlight assessments have changed so much over the past number of years, and reports have become far more complex, it’s no wonder why there are so many questions to answer, not to mention the confusion amongst clients and design teams. The quantity of assessments to be carried out has also increased significantly leading to more data being captured which in turn leads to more explanation.

The following are the top questions we at 3DDB receive frequently. Other articles in the links below provide more detailed information.

Which guidelines should be used?

It is the opinion of 3D Design Bureau that the best practice for daylight and sunlight assessments is to follow the guidance of the BRE Guidelines (BRE 209) 2022. Internal daylighting to units should also be tested under IS-EN 17037 standards and compliance rates given for both. For a detailed look at the guidelines and standards to use for daylight and sunlight assessments, visit Expert Insights on the Latest BRE Daylight & Sunlight Assessment Guidelines.

Do you need to test the entire scheme for internal daylighting?

Whilst it does state in the BRE 209 that daylight access will improve the higher up a building you go (due to less external obstruction), the best practice is to test the entire scheme. This means all habitable rooms of all units. This provides a clear understanding of the performance of a building. It is also a requirement under the DCC Development Plan. For more detailed information on this metric and others, visit All you need to know about scheme performance for the latest edition of BRE Daylight and Sunlight Assessments and All You Need to Know about Impact Assessments for the latest edition of BRE Daylight and Sunlight Assessments.

Do you need to include trees in daylight and sunlight assessments?

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