Methodology
Pubs In The Sun uses 3D raytracing — the same technique used in visual effects and architectural sun studies — to calculate exactly how much direct sunlight each outdoor pub space receives, for any hour of any day of the year.
Most outdoor seating apps just tell you a pub has a garden. A few tell you it faces south. But a south-facing garden surrounded by four-storey Victorian terraces on three sides gets almost no direct sun at all. Generic orientation data misses the thing that actually matters: what percentage of the seating area receives direct sunlight at a given time of day?
We start by building a 3D model of every outdoor seating area and its surrounding buildings. This uses open mapping data combined with building height surveys. Each outdoor space is modelled as a polygon at ground level. Each surrounding building is modelled as a solid block with its real height. The result is a precise geometric representation of the sun's shadow environment at that location.
For any given date, time, and geographic coordinate, the sun's altitude and azimuth can be calculated exactly from astronomical formulae. We run this calculation for every hour of the day, for every day of the year — 366 days × roughly 13 daylight hours = over 4,700 sun positions per pub.
For each sun position, we cast rays from the sun down onto the outdoor seating polygon. A ray that reaches the ground unobstructed counts as direct sunlight. A ray that intersects a building on the way means that part of the seating area is in shadow. By counting the proportion of rays that reach the ground, we calculate the exact percentage of the outdoor seating area that is in direct sunlight at that time.
The sun percentage shown on every pub in the app is the result of this raytracing calculation for the current time and date. The time slider shows how sun coverage changes throughout the day. The best sun time displayed on pub profiles is the continuous time window with the highest average sun coverage. All of this is recalculated for each day of the year, so January and July give you accurate, different answers.
Our calculations are highly accurate for clear sky conditions. We model permanent structures — buildings, walls, and fixed overhead structures. We do not model temporary obstructions such as umbrellas, awnings, or seasonal foliage, and we do not account for weather. A pub that scores 85% sun on a cloudy day will still show 85% — that's the maximum possible, not the guaranteed amount. We recommend using the data as a planning tool: find the pubs that would be sunniest, then check the forecast.
We currently cover 1,000+ pubs across London. New pubs are added regularly as we process their 3D models. Sun data is recalculated periodically to keep up with new buildings and corrections to the 3D models. If you know a pub that should be on the app, use our Submit a Pub form.