Article

Nighttime heat - a workshop on data and maps needed to adapt cities to increasing nighttime heat

Presentation by Jeroen Kluck, Lisette Kok, Noortje Oosterhoff and Remo van Tilburg

Municipalities have to make choices about making their cities heat-resilient. Also, architects and building managers become more and more aware that they need to take into account the consequences of heat events and increased indoor temperatures. To understand the problems of extreme heat, several temperature maps have been developed for the Netherlands:

1) maps with the perceived temperature during a hot day,
2) maps with the urban heat island effect and
3) maps with the number of warm nights.

The session is divided in different presentations and discussions:
1) Presentation by prof. Jeroen Kluck (Hogeschool van Amsterdam )– Nighttime heat problems: how often and where?
2) Presentation by Remo van Tilburg and Noortje Oosterhoff (Nelen & Schuurmans) – UHI – where in the city
3) Cases – parallel discussions

The video of the workshop can be found here

Maps showing the perceived temperature during a hot day are useful to point out cool spots and areas with high heat stress that could be designed more heat-resilient. Maps with nighttime temperatures are especially relevant to indicate problems related to indoor climate, health and labor productivity. However, there are quite a few uncertainties in the design and the use of the current map of the number of warm nights that exists for the Netherlands. 

First of all, it can be argued if the number of warm nights is the best indicator to understand the problems related to nighttime heat. And if so, could this indicator also be used as a basis for guidelines to reduce problems related to nighttime heat or for formulating heat-resilient ambitions? Or should other climate indicators or maps be used instead? Knowledge about nighttime temperatures and its spatial variation in cities is for instance important to understand if specific urban areas are more vulnerable with respect to nighttime heat and increased indoor temperatures. 

Information on nighttime temperatures is also needed to assess the options for natural window ventilation to reduce indoor temperatures, and to understand to what extent the urban heat island effect or the percentage of greenery influences the cooling potential of homes or other buildings in a city. It is likely that the number of warm nights is not the appropriate indicator to examine this. 

The desired outcome of this workshop is a description of a map or data on nighttime temperatures to include in the climate impact atlas. Besides, this workshop may also lead to a joint research proposal for making a new nighttime temperature map.

Image credits

Header image: Amsterdam Pixabay.png

Icon image: Amsterdam Pixabay.png