Methods & Data
These layers come from a global, building-level canopy and heat model — the same study that covers roughly 9,000 cities worldwide. They are model outputs suitable for mapping, visualisation and screening; they are not a substitute for local field survey or cadastral data, and should not be cross-quoted with finer local datasets.
What we measured
For every building we computed two things within a 60-metre radius — the neighbourhood-scale zone where tree shade measurably cools the surrounding air:
- Tree canopy (%) — the share of ground within 60 m covered by tree canopy.
- Land-surface temperature (°C) — how hot the surfaces around the building get in the hot season.
A building is counted as below threshold when tree canopy within 60 m is under 30% — the minimum canopy benchmark for heat-safe homes in the widely cited “3-30-300” rule.
Data sources
| Input | Source | Notes |
|---|---|---|
| Tree canopy | Meta Canopy Height Model v2 | Tree vegetation ≥ 2 m; % cover within 60 m of each building. All-vegetation (≥ 1 m) also available. |
| Surface temperature | Landsat 8/9 LST | Hot-season maximum composite, 2022–2024. A surface (not air) temperature and a peak value. |
| Building footprints | Overture Maps | Height, class, and dwelling estimates where available. |
| Population / dwellings | GHS-POP R2023A | Dasymetric; city totals validated vs WorldPop (global r ≈ 0.97). |
| City boundary | GHSL Functional Urban Area | Commuting-zone scale — larger than the municipal city-proper. |
Important caveats
- Surface temperature is relative. It is satellite-derived, a hot-season maximum, and reads the sunlit tops of surfaces — so it runs hotter than air temperature and under-registers shade beneath trees. Use it to compare places, not as a thermometer reading.
- No equity layer. The global deprivation proxy (GRDI) is unreliable in rich, dense European countries, so no deprivation/income analysis is included here rather than shipping something misleading.
- Functional urban areas. City extents are commuting-zone scale, so per-city figures are FUA-scale (they include suburban and peri-urban fabric, not just the historic core).
- Model, not survey. Figures are screening-grade model outputs, not cadastral or field-measured canopy.
Per-city summary
| City | Buildings | Mean canopy | Buildings < 30% | Mean summer surface temp | Population (urban area) |
|---|---|---|---|---|---|
| Basel | 148,418 | 18.6% | 83.4% | 44.0 °C | 479,464 |
| Bern | 134,626 | 17.1% | 84.7% | 42.3 °C | 410,613 |
| Biel/Bienne | 55,480 | 15.8% | 89.9% | 42.5 °C | 169,104 |
| Fribourg | 39,845 | 12.1% | 93.0% | 41.7 °C | 140,716 |
| Geneva | 93,567 | 23.0% | 72.5% | 37.6 °C | 558,294 |
| Lausanne | 83,168 | 16.6% | 86.7% | 44.2 °C | 430,950 |
| Lucerne | 82,079 | 11.4% | 93.5% | 45.3 °C | 350,160 |
| Lugano | 69,625 | 20.8% | 77.0% | 40.9 °C | 180,976 |
| Montreux | 40,582 | 16.4% | 85.9% | 42.1 °C | 148,198 |
| Olten | 93,478 | 12.6% | 93.2% | 43.7 °C | 238,591 |
| St. Gallen | 76,797 | 13.6% | 91.6% | 38.9 °C | 267,053 |
| Thun | 52,216 | 13.0% | 92.3% | 43.7 °C | 130,225 |
| Zurich | 494,234 | 17.1% | 86.0% | 44.7 °C | 2,112,549 |
Global Urban Canopy & Heat Exposure Study, prepared 2026-07-17. Contact the study lead for method detail, validation, or finer datasets where a city overlaps them.