Sunlight & Overshadowing Assessment
BRE Guide BR 209 — Sun Hours on Ground & Overshadowing Analysis
Proposed Building Details
Enter details of the proposed development to assess potential overshadowing impacts on neighbouring properties and open spaces.
Neighbouring Properties
Add up to 4 neighbouring properties. Expand each section to enter details.
Open Spaces Assessment
Enter details of amenity spaces that may be affected by overshadowing.
Shadow Analysis Summary
Estimated shadow lengths at key times on March 21st (52°N latitude, sun altitude at noon: 38°)
Shadow calculations based on solar geometry for UK latitude (52°N) on the spring equinox (21 March).
Neighbouring Property Impact Assessment
Sun-on-Ground Assessment (Amenity Space)
BRE Line Tests
BRE Compliance Summary
Key Recommendations
About this tool: Sunlight & Overshadowing
Sunlight and overshadowing assessment for gardens and open space — shadow path reasoning and the two-hour sun-on-ground test.
Use when your proposal could overshadow neighbouring gardens, amenity space or public open space.
BRE Report 209
Use these tools when designing your scheme or reviewing drawings. They help ensure your proposal meets technical standards before submission, reducing the risk of officer objections on design grounds.
Guidance to help you prepare — not formal planning advice. Check the current policy text and your council's local plan before relying on it.