ICTU: An Open Index of How Hot the City Feels
This overview was generated with AI from the public sources listed below and checked against them before publication. It has not had a complete human fact-check — treat it as a starting point and follow the sources.
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Bordeaux Metropole's urban thermal comfort index (ICTU) grades every 2-metre square of the metropole from 3 (comfort) to 0 (discomfort), modelled by the engineering firm Verdi from a summer 2021 measurement campaign that combined aerial thermography, satellite data and morphological databases of building density, ground cover, canopy and water stress. Rather than stop at surface temperature it was calibrated against how people actually felt: connected temperature and humidity sensors at 80 measurement points across eleven sites, plus more than 500 responses to QR codes posted in the street. It cost about 80,000 euro, three quarters of it from the national France Relance recovery plan, and is published openly on the metropole's DataHub as a raster and as a 250-metre hexagon layer of 11,056 cells. Bordeaux Metropole says the index won the Energy and Environment category at the World Smart City Awards in Barcelona on 8 November 2023.
what does this mean?
The strongest source is the operator's or the city's own reporting — an official report, dataset or press release. It grades who did the looking — not how well the project went. All four grades →📊 Impact
The index covers the whole metropole and feeds planning work rather than an alert: the urban agency a-urba used it in 2023 to build a heat-vulnerability map at 200-metre resolution and concluded that 52% of the metropole's population is in a situation of strong to very strong vulnerability during a heatwave. The measurement campaign produced specific findings the city acted on — that some tree species stop cooling above 30 degrees, and that existing plantings in the allees de Tourny no longer delivered a cooling benefit.
🎓 Lesson
The index is still the summer 2021 campaign. Its geographic metadata declares annual updating, but no newer vintage of the raster has been published, and the 2026 refresh of the hexagon layer is a re-derivation of the same 2021 data rather than a new measurement. An award-winning diagnostic is cheap to build once and expensive to keep current; nothing in the published data shows how the index changes as the metropole plants trees.
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📎 Cite this project
1001 Smart Cities (2026). “ICTU: An Open Index of How Hot the City Feels” — Bordeaux, France. The Smart City Atlas. https://1001smartcities.org/projects/bordeaux-ictu-thermal-comfort/ (last verified 2026-08-10). Data: CC BY 4.0.
The underlying data is free to reuse with attribution — see the open data page.