Hot Town! Summer in the city

Abstract

Cities face challenges protecting their population from high air temperatures. In the coming century cities tend to become warmer as a consequence of global warming exacerbating the urban heat island. This affects the livability of neighbourhoods with negative effects for the population. The urban heat island is the phenomenon where the city warms up during the day and remains warmer during the evening and night then its surroundings. This is a consequence of urban characteristics like lack of vegetation and use of paved surfaces. However the urban heat island is spatially uneven distributed and some residents are more exposed. These neighbourhoods are often socially deprived neighbourhoods. Residents in these neighbourhoods are of low income and have bad health. In combination with badly insulated houses and a public space that does not provide room for coolness these people are disproportionately exposed. Such exposure to the hazard of high air temperature is considered as an issue of environmental justice. The city of Rotterdam has a strong urban heat island and above average percentage of people with low income. As such the thesis focuses on if there is a relation between Rotterdam’s socially deprived neighbourhoods and the urban heat island. Are people in these neighbourhoods disproportionately exposed to the urban heat island? If so, how can urban design mitigate and adapt to the negative effects of the urban heat island. With the use of a Pearson correlation analyses a correlation is found between the urban characteristics of neighbourhoods and the averages summer day surface temperature, which acts as an indicator for the urban heat island, fitting urban heat island theory. Interestingly population characteristics also correlate. Neighbourhoods that tend to have a strong urban heat island are also socially deprived. Such a combination is considered as an issue of environmental justice. Residents in these neighbourhoods are more exposed and vulnerable since they also have bad health conditions. Due to urban characteristics of lack of green and high percentage of paved surfaces the neighbourhood does not provide, both in the private and public space, room to escape from the urban heat island. Such an issue of environmental justice is considered to be the most severe in the city district of Feijenoord. Design interventions are proposed for the neighbourhood of Bloemhof. These range from the introduction of courtyard building blocks, to introducing vegetation in both the public and private space. The introduction of courtyard building blocks provides a typology in which the inner courtyard provides for coolness. The typology also attends to introducing more diversity and population density in the neighbourhoods. With the use of urban heat island mitigating and adapting design principles the building block and its direct surroundings remains relatively cool. More vegetation is introduced in both the public and the private space. A neighbourhood deal is proposed between the residents, the municipality and the housing corporation. In the private space of gardens with a high percentage of paved surfaces the tiles are removed with vegetation. With a careful selection of vegetation these gardens are easy to maintain and not expensive. Firstly the residents are provided with room in their private space to escape from the urban heat island. Secondly such a proposal reduces urban characteristics that contribute to the urban heat island. In the public space on street level vegetation is introduced that covers the facades and tiles along the facades are replaced with vegetation. For squares more vegetation is proposed, with playgrounds and benches in the shade and communal gardens. In retrospective the thesis introduces the concept of environmental justice on the city scale within the Dutch context. Broadening the scope how the urban heat island affects the population. Future research on the urban heat island should incorporate the concept of environmental justice as it will give a deeper insight in who will be most exposed by the urban heat island.