Frank van der Hoeven

Amsterwarm: Mapping the landuse, health and energy-efficiency implications of the Amsterdam urban heat island

The Amsterwarm project investigates the urban heat island of Amsterdam, the vulnerability of its population, the energy efficiency of its buildings and landuse. A novel mapping approach provides insights into the questions of what causes the urban heat island and who will be affected by it. Landuse does affect the surface temperature. The difference between the areas in the city with the least and the greatest impervious surface coverage accounts for an average land surface temperature difference of 11.6℃ per hectare. The study demonstrates furthermore that the vulnerability of people and buildings to the urban heat island effect is a local condition in which the energy efficiency of buildings, quality of life and demographic factors should all be considered in an approach that is sensitive to place. Practical application: The typological maps will allow local authorities to prioritise adaptive actions in urban planning in response to the urban heat island, an emerging climate-related challenge that has a significant impact on the comfort and health of its citizens and on the (future) energy use required for cooling buildings. Raising the albedo in those areas of the city that are dominated by impervious surface cover seems an effective adaptation strategy, suitable to a city such as Amsterdam that no longer builds on green field sites but only builds as possible within the envelope of the existing city. Improving the quality of life in neighbourhoods and the energy efficiency/climate proofing of the building stock could also be prioritised in the identified neighbourhoods.

Surface thermal analysis of North Brabant cities and neighbourhoods during heat waves

The urban heat island effect is often associated with large metropolises. However, in the Netherlands even small cities will be affected by the phenomenon in the future (Hove et al., 2011), due to the dispersed or mosaic urbanisation patterns in particularly the southern part of the country: the province of North Brabant. This study analyses the average night time land surface temperature (LST) of 21 North-Brabant urban areas through 22 satellite images retrieved by Modis 11A1 during the 2006 heat wave and uses Landsat 5 Thematic Mapper to map albedo and normalized difference temperature index (NDVI) values. Albedo, NDVI and imperviousness are found to play the most relevant role in the increase of night-time LST. The surface cover cluster analysis of these three parameters reveals that the 12 “urban living environment” categories used in the region of North Brabant can actually be reduced to 7 categories, which simplifies the design guidelines to improve the surface thermal behaviour of the different neighbourhoods thus reducing the Urban Heat Island (UHI) effect in existing medium size cities and future developments adjacent to those cities.