Assumptions & limitations for heat stress
This section details the assumptions and limitations per provided dataset (see Data access).
The above sets of maps provide an indication of outdoor exposure. Maps for indoor exposure still need to be developed. The PET gives an indication of the impact of meteorological conditions on a person (outdoors, without activity). For insight into other impacts, refer to the NAS Adaptation Tool or the Heat mind map. The PET map also does not show how high indoor temperatures may rise. Such maps are currently being developed. More information on heat in houses is provided in the Guidelines for Heat in Existing Houses.
One of the key limitations of the Urban Heat Island (UHI) effect map is that it only presents annual average temperature differences, without capturing extreme temperature events. During periods of extreme weather, urban temperatures can rise significantly above these averages, potentially leading to more severe impacts than the map suggests.
The Warm Nights map also has notable limitations. It is based solely on temperature measurements from Rotterdam, which reduces the reliability and representativeness of the results for other regions in the Netherlands. Additionally, the cooling effects of major water bodies such as large rivers and lakes, which can significantly influence local nighttime temperatures, are not taken into account.
When using the Distance to Cooling map, take into account that the current version is based on an earlier version of the perceived temperature map, which may affect accuracy. An update to the methodology is needed to improve the results.
Other remarks are mentioned in the technical notes (PDF), and include:
- Small cool spots may be missed if too fragmented.
- Only public green spaces are included, and private gardens are excluded.
- Analysis is limited to urban areas, based on Topographic Nederland (1:10.000) excluding rural zones.
- Some spots may be inaccessible due to vegetation.
- Narrow shapes are excluded, though they might still offer cooling.
- Weather data from one day may skew results, especially in the north.
- Distance calculations may be off due to missing or misclassified paths.
- Building entrances are assumed to be on the road, which may distort walking distances.
The map Shaded footpaths and cycle tracks only shows separate cycle tracks. Cycle lanes on roadways are not listed on the Basic Registration of Large-Scale Topography (BGT) and thus not reflected on the map. Also, the shade was calculated for 3.30 PM, as statistically this is the hottest time of the day, however this is subject to the weather on the specific day. The selected date and time of day are in line with the points of departure set out in the Benchmark for Green Climate Adaptive Built Environment, and are comparable with the points of departure underpinning the Perceived temperatures heat map.
