A solar glare assessment looks at whether sunlight — either direct, or reflected off glazing and solar panels — will cause a hazardous or unacceptable level of glare for the people who have to look towards it. Most domestic and small commercial schemes never need one. A minority do, and being asked for a solar glare assessment late in a planning determination can hold a decision up for weeks if it is not anticipated.
This guide explains, in plain terms, when a UK planning application genuinely needs a solar glare assessment, what the assessment actually examines, and how it sits alongside the daylight and sunlight report most schemes already require. It is written for architects, developers and homeowners trying to work out whether glare is a real issue for their site or simply a box someone has ticked out of caution.
What a solar glare assessment is
The term covers two related but distinct things, and confusing them is the most common reason people end up commissioning the wrong study.
The first is glare inside a building — discomfort or disability glare experienced by occupants when bright sky, low sun or a strongly contrasting bright patch falls in their field of view. This is addressed by BS EN 17037, the daylight standard now embedded in the UK through the third edition of the BRE guide (BR 209, 2022). The standard recognises that overly bright areas, or strong contrast between light and dark, can be a problem for the eye, and recommends that protection from glare is provided where people cannot choose their position or viewing direction.
The second is glint and glare from reflective surfaces — typically solar photovoltaic panels, large areas of glazing or metal cladding — affecting people outside the building: drivers on a nearby road, train operators, or aircraft pilots and air-traffic controllers near an airfield. This is the assessment highway authorities and aviation bodies ask for, and it is a quite separate piece of work from an internal daylight study.
Both are sometimes loosely called a “solar glare assessment”, so the first job on any project is to establish which one a consultee is actually concerned about.
When internal glare matters under BS EN 17037
For ordinary housing, internal glare rarely drives a planning decision. The BRE guidance and the underlying standard accept that in homes occupants can move, turn away, or close a blind or curtain, so the potential for disabling glare is usually manageable without formal assessment. As a general rule, a glare study is unlikely to be required for a straightforward residential scheme.
It becomes relevant where people cannot readily control their position or shade the window — for example a workplace with fixed desks facing low afternoon sun, a classroom, a healthcare or care setting, a sports hall, or a large fully glazed elevation facing east or west. In those cases an assessment can confirm whether shading, glazing specification or orientation needs to change. It also overlaps with summertime comfort: where you are already considering solar gain and overheating, glare is a natural companion question. We cover that comfort balance in our note on daylight versus overheating under Part O.
When glint and glare from reflections matters
The reflective form of glare is the one most likely to appear as a formal planning condition or a consultee request. It is typically raised where a proposal introduces large reflective surfaces close to a sensitive receptor:
- Solar farms and large rooftop PV arrays beside a busy road, motorway or railway line, where a highway or rail authority may ask for the reflection risk to drivers or train operators to be investigated.
- Development near an aerodrome, where aviation stakeholders assess potential glare towards the runway approach or the control tower.
- Tall or extensively glazed buildings whose facades could throw reflected sun onto a junction, footway or neighbouring windows.
In these situations the highway authority or local planning authority will often flag glint and glare as a possible risk before determining the application, and ask for it to be investigated. The BRE 2022 guidance reflects the rising profile of this issue, considering the impact on and from solar panels for the first time. A glint-and-glare study models the geometry of the sun, the reflecting surface and the receptor across the year, works out when and for how long a reflection could occur, judges whether it would be a genuine hazard, and where necessary recommends mitigation — screening, planting, panel angle or an anti-reflective finish.
How it relates to your daylight and sunlight report
A standard daylight and sunlight report deals with the amount of natural light reaching habitable rooms and amenity space. It is built around the familiar BRE metrics — Vertical Sky Component, No-Sky Line and Annual Probable Sunlight Hours — which we explain in our guide to VSC, NSL and APSH. Glare is the mirror image of that question: not too little light, but too much of it from the wrong angle.
Because the two share the same solar geometry, an internal glare check can often be carried out alongside a daylight assessment using the same model. A reflective glint-and-glare study for a road or aerodrome is more specialised and is usually scoped separately, but it still benefits from being coordinated with the daylight work so the project is not paying twice to build the same site model. The practical message is simple: identify early which kind of glare your site could raise, and fold the right check into your assessment strategy rather than bolting it on after a refusal.
How to tell whether your scheme needs one
A few questions will usually settle it:
- Are you introducing significant reflective surfaces — PV panels, large glazed or metal facades — within sight of a road, railway or airfield? If yes, expect a glint-and-glare request and plan for it.
- Will occupants face fixed bright views they cannot turn from or shade, in a workplace, school or care setting? If yes, an internal glare check under BS EN 17037 is worth doing.
- Is this ordinary housing with normal windows and the usual blinds and curtains? If yes, a formal glare assessment is very unlikely to be needed — your daylight and sunlight report will normally suffice.
- Has a consultee, condition or validation checklist specifically named glint, glare or reflection? If yes, treat that as the definitive trigger and respond to the precise concern raised.
When in doubt, it is cheaper to ask the case officer what they actually want than to commission the wrong study. If you are unsure, our team is happy to look at your site and tell you honestly whether glare is a real issue or not — get in touch and we will give you a straight answer.
How Fortress Associates can help
Fortress Associates prepares daylight and sunlight reports for planning across the UK, and we can advise whether your scheme needs a glare check folded into that work or a separate glint-and-glare study scoped in. We work to BRE BR 209 (2022) and BS EN 17037, turn most reports around in four to five working days, and ask for no advance payment. You can see the full scope of our work on our services page, and we will always tell you when an assessment is genuinely not required rather than sell you one you do not need.
Sources & further reading
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