Daylight and Sunlight
Assessment
Blue Sky Surveyors are specialist daylight and sunlight surveyors providing expert assessments for planning applications, development projects, and objections to neighbouring developments across London and the UK.
Services are available to developers needing a daylight and sunlight assessment to support a planning application, architects seeking early-stage design advice, and neighbours concerned about the impact of a proposed development on their property.
What is a Daylight and
Sunlight Assessment?
A daylight and sunlight assessment is a technical evaluation of the natural light conditions at a property or development site, carried out for the purposes of a planning application. Assessments are carried out in accordance with the Building Research Establishment’s guidance document BR209, most recently updated in 2022.
Local planning authorities across England and Wales rely heavily on BRE guidelines when assessing planning applications involving new development. An assessment examines both the impact of a proposed development on neighbouring properties and the internal daylight and sunlight conditions within the proposed development itself.
BRE Guidelines - An Overview
The BRE guidelines (BR209) are the UK’s primary framework for assessing daylight and sunlight in the context of planning applications. Although advisory rather than mandatory, they carry significant weight in the planning process and most local planning authorities treat them as a key material consideration.
The guidelines were substantially updated in 2022, introducing more sophisticated assessment methodologies for new dwellings and aligning with the British Standard for daylighting in buildings (BS EN 17037). Blue Sky Surveyors are fully up to date with all 2022 changes.
Key Assessment Methods
Vertical Sky Component (VSC)
The Vertical Sky Component measures how much of the sky is visible from the centre of a window on an existing neighbouring property. The BRE guidelines recommend a VSC of 27% or more. Where a development would reduce the VSC by more than 20% of its former value, this may indicate an unacceptable impact.
No Sky Line (NSL) / Daylight Distribution
The No Sky Line test examines how much of a room’s floor area can receive direct daylight from the sky. Where this area is reduced by more than 20% as a result of a development, the change may be significant under BRE guidelines.
Annual Probable Sunlight Hours (APSH)
The APSH test measures the amount of direct sunlight a window can receive throughout the year. The BRE guidelines recommend that a window should receive at least 25% of annual probable sunlight hours, including at least 5% during the winter months.
Sunlight to Gardens and Amenity Areas
For gardens and outdoor amenity areas, the BRE guidelines recommend that at least half of the area should receive a minimum of two hours of direct sunlight on 21 March.
Internal Daylight — New Dwellings
For new residential accommodation, the 2022 BRE guidelines introduced new climate-based illuminance tests, replacing the former Average Daylight Factor (ADF) methodology. These calculations assess daylight conditions across the entire year, providing a more accurate picture of natural light levels for future occupiers.
Our Daylight and Sunlight Services
Daylight and Sunlight Assessments for Planning
Comprehensive daylight and sunlight assessments are prepared to support planning applications, covering both the impact on neighbouring properties and the internal conditions within new development.
Pre-Application Advice for Developers
Early engagement with a daylight and sunlight specialist can save significant time and cost during the design process. Blue Sky Surveyors work with developers and architects at the pre-application stage to identify constraints and advise on design modifications before a planning application is submitted.
Daylight and Sunlight for Objectors
Where a neighbouring development raises concerns about daylight and sunlight, an independent assessment can be carried out to establish the extent of the impact and advise on the options available.
Expert Witness Services
Blue Sky Surveyors are experienced in providing expert witness evidence in planning appeals, public inquiries, and legal proceedings relating to daylight and sunlight matters.
Daylight and Sunlight vs Rights of Light
It is important to understand the difference between daylight and sunlight assessments and rights of light. A daylight and sunlight assessment is carried out for planning purposes under BRE guidelines. Rights of light, by contrast, is a legal property right that can be enforced through civil litigation, entirely independently of the planning system.
A development can comply with BRE guidelines for planning purposes yet still infringe a neighbour’s legal right to light. Blue Sky Surveyors are specialists in both areas.
Read our complete guide: What is a Right to Light?
Frequently Asked Questions
When is a daylight and sunlight assessment required for planning?
Most local planning authorities require a daylight and sunlight assessment for any development that could affect the daylight and sunlight conditions of neighbouring properties – typically new residential developments, extensions above a certain scale, and commercial developments where neighbouring properties could be affected.
Are BRE guidelines mandatory?
The BRE guidelines are advisory rather than mandatory. However, they carry significant weight in the planning process and most local planning authorities treat compliance with them as an important material consideration.
How long does a daylight and sunlight assessment take?
For straightforward residential schemes, an assessment can typically be completed within two to three weeks of receiving all necessary information. For larger or more complex schemes, a programme is agreed at the outset.
Can a development proceed if it fails BRE guidelines?
A failure to comply with BRE guidelines does not automatically mean a planning application will be refused. Planning authorities must weigh up all material considerations, and there are many cases where permission has been granted despite non-compliance, particularly in dense urban environments.