The UK Building Exterior Index 2026

Method, in full

City set

Fifteen Great Britain cities: London, Birmingham, Manchester, Leeds, Sheffield, Liverpool, Bristol, Newcastle, Nottingham, Leicester, Brighton, Reading, Cardiff, Glasgow and Edinburgh. Great Britain only, because the heritage and building age sources differ in Northern Ireland and a clean like for like was not possible for this release.

Reference periods

Air pollution uses the latest full calendar year of annual mean PM2.5 available per city. Climate uses a fixed five year mean of annual rainfall from 2020 to 2024. High rise counts are completed or topped out buildings of 100m or more as recorded in early 2026.

Normalisation and scoring

Each raw stressor is rescaled to a 0 to 100 range with min to max normalisation across the 15 cities, so the lowest city on a measure scores 0 and the highest scores 100. The composite is the weighted sum of the five normalised sub scores, then itself reported on the same 0 to 100 footing. Because scores are relative within this set, adding or removing a city would shift them; the index ranks these cities against each other, it does not assign an absolute physical quantity.

Weights

Weights reflect how directly each stressor drives facade soiling and decay, and how well measured each layer is in this release:

Rain and pollution carry the most weight because they are the two largest, best evidenced drivers of how fast a facade soils and degrades. High rise density reflects exposure and the cost and difficulty of safe access. Age and heritage modulate how vulnerable the stock is, but in this first release they are indicative rather than directly measured, so they carry the lightest weights.

Robustness

UK city PM2.5 sits in a narrow band, roughly 7 to 9 micrograms per cubic metre across English and Welsh cities and lower in Scotland, so the pollution layer separates cities less sharply than rainfall does. The 100m high rise threshold concentrates that layer in London and Manchester. Both effects are visible in the table and are the reason no single layer is allowed to dominate the composite.

Limitations, stated plainly

Three of the five layers (pollution, rain, high rise) are built from measured public data. Two layers (building age and heritage load) are indicative v1.0 estimates grounded in published urban history and the known character of each city, not yet pulled per city from the primary registers. They are clearly labelled with an asterisk in the table and given the lightest weights. The wind driven rain layer uses regional rainfall as a proxy for city level wind driven rain, so a city inherits its region's figure; this is the main planned refinement. The next release will replace the age layer with EPC open data construction age bands and the heritage layer with listed building and conservation area counts from Historic England, Historic Environment Scotland and Cadw.

Reproducibility and licence

The full table is downloadable as a CSV that includes every sub score and the raw inputs behind it (PM2.5 in micrograms per cubic metre, five year mean rainfall in millimetres, count of buildings over 100m, and the indicative age and heritage indices). The dataset is released under a Creative Commons Attribution 4.0 licence: you may republish or build on it, including commercially, with attribution to Envelium.