internal daylight assessment
An Internal Daylight Assessment demonstrates the daylight quality of proposed rooms de-risking validation, officer review and committee. We model to BRE 209 expectations using appropriate metrics (e.g., DF/UDI/NSDTM as agreed with your LPA) and give clear, design-led fixes that protect layout and GIA.
What is an Internal Daylight Assessment
It quantifies daylight within proposed rooms (living/kitchen/dining, bedrooms, studios), showing whether they achieve reasonable daylight under the relevant guidance. We coordinate with neighbouring VSC/NSL/APSH and overshadowing so your planning narrative stays consistent.
2-4 Ringers Road, Bromley
Wadworth Brewery, New Park Street
360, 17 Marlborough Street, Bristol
At-a-glance
| Topic | Internal Daylight (Proposed Rooms) | Neighbouring Windows (for context) | Overshadowing (Open Space) |
|---|---|---|---|
| Metrics | DF/UDI/NSDTM (as agreed with LPA) | VSC/NSL/APSH (BRE 209) | % area with ≥2h sun on 21 March (BRE 209) |
| Purpose | Demonstrate good daylight for new homes/rooms. | Show impact on neighbours to support planning balance. | Evidence sun access to gardens/courtyards. |
| Typical Triggers | Deep plans, small windows, recessed façades, ground/1st floors. | Tight grain; massing near windows. | Tall/long forms near amenity space. |
| Design Levers | Window size/position, higher transmittance glazing, lighter finishes, layout flips, lightwells/slots. | Setbacks, step-backs, chamfers, local height trims. | Height trims, gaps, orientation tweaks. |
| Outputs | Room-by-room schedules and diagrams with narrative. | Tables, drawings, policy commentary. | Plans/diagrams with % compliance. |
Why appointment a surveyor
- Officer-friendly evidence: clear schedules, diagrams and narrative aligned to local policy.
- Design certainty: change only what moves the metric—window sizing/position, room layout, reflectance, lightwells.
- Viability: protect saleable area and layouts with targeted tweaks.
- Speed: scoped to your LPA; fast addendums for late design changes.
- Joined-up approach: internal daylight coordinated with external BRE and Right to Light.
Faq
Got questions about right to light in London?
Below are answers to the most common right to light questions we receive from London homeowners, architects and developers covering law, process, fees and what to send us.
No. Internal daylight is a planning amenity test for proposed rooms. Right to Light is a legal easement about neighbours’ existing windows.
Typically a mix of window size/position/transmittance, lighter finishes, selective layout changes, and where feasible lightwells or shallower reveals.
They’re more challenging due to obstructions and sky view. We target façade tweaks and interior reflectance to lift performance.
Often. BRE is guidance, not law we provide contextual justifications (design quality, dual-aspect gains, views, noise/overheating trade-offs).
Yes! so your submission tells one consistent story across all light topics.