Thermal comfort (UTCI) map
The «Thermal comfort» tab combines the weather file, the wind simulation, building and tree shade and ground cover to compute UTCI at each point.
Overview
The thermal comfort map is for deciding, at concept stage, whether an outdoor space is a place where people can sit in summer. Most of the inputs are results that other tabs have already produced.
How to use
- Choose the site and the radius
- On the «Thermal comfort» tab, choose the period (summer, spring, autumn, winter or annual)
- Choose the time (10:00, 14:00 or 18:00, standard time without summer time)
- Start the calculation
If a wind simulation for the same site and period exists, the calculation takes a few seconds; otherwise the wind simulation runs first.
UTCI and categories
UTCI (Universal Thermal Climate Index) combines air temperature, humidity, wind speed and radiation into one felt temperature, in °C.
| UTCI | Category |
|---|---|
| 9–26 °C | No thermal stress |
| 26–32 °C | Moderate heat stress |
| 32–38 °C | Strong heat stress |
| 38–46 °C | Very strong heat stress |
| 46 °C or more | Extreme heat stress |
Cold categories (below 9 °C) are defined the same way and are used in winter.
Method
| Input | Data |
|---|---|
| Temperature, humidity, solar radiation | TMYx weather file of the nearest station (the same file as the wind rose) |
| Wind speed | Result of the «Wind» simulation |
| Shade and sky view | Building height map (3DBAG), AHN4 terrain, and trees detected from the aerial photo |
| Ground cover | Green space and tree crowns |
For tree shade every crown is given an assumed height of 8 m; the screen note states this.
Limitations
Indicative simulation, not a regulatory assessment. Compare places, not the numbers.
- Pedestrian-level wind comes out too weak; on the Seoul and Tokyo sample sites 81–89% of cells sit at the lowest wind the UTCI formula accepts (0.5 m/s), so open, windy places read warmer than reality (less cold in winter)
- Surface properties (albedo, emissivity) are literature values, not measurements
- Buildings finished after 2022 may have no 3DBAG height
Related guides
Example plates: BAG (Kadaster, CC0) · © 3DBAG by tudelft3d and 3DGI (CC BY 4.0) · BGT, NWB, AHN4 (CC0) · Kadaster, Beeldmateriaal.nl, PDOK (CC BY 4.0) · © OpenStreetMap contributors (ODbL)