Heatwaves in urbanized areas, even in temperate regions like the Netherlands, are getting serious attention. The Royal Netherlands Meteorological Institute predicts more frequent and intense heat events in the future. Studies have explored how Dutch cities contribute to heatwaves and suggested design and planning responses to mitigate their effects. However, a review of heatwave research in the Netherlands specifically focusing on the built environment has hardly been reported in the literature. This study aims to provide such a review utilizing the vulnerability framework. Following the PRISMA protocol, 57 articles are analysed based on the components of exposure, sensitivity, and adaptive capacity within the vulnerability framework. Subsequently, findings have been classified into five built environment scales - block, neighbourhood, district, city, and region - to critically reflect upon the extent to which the studies address various vulnerability components and the specific scales they primarily focus on. Results demonstrate that most of the studies concentrate on the hazard itself and its spatial distribution from a macro perspective on a city and regional scale. The review underlines the necessity of micro-level research on the phenomena, incorporating people's everyday experiences and resilience during heat events to find context-specific adaptation and mitigation strategies.@en

Morphological characteristics of cities significantly influence urban heat island intensities and thermal responses to heat waves. Form attributes such as density, compactness, and vegetation cover are commonly used to analyse the impact of urban morphology on overheating processes. However, the use of abstract large-scale classifications hinders a full understanding of the thermal trade-off between single buildings and their immediate surrounding microclimate. Without analytical tools able to capture the complexity of cities with a high resolution, the microspatial dimension of urban climate phenomena cannot be properly addressed. Therefore, this study develops a new method for numerical identification of types, based on geometrical characteristics of buildings and climate-related form attributes of their surroundings in a 25m and 50m radius. The method, applied to the city of Rotterdam, combines quantitative descriptors of urban form, mapping GIS procedures, and clustering techniques. The resulting typo-morphological classification is assessed by modelling temperature, wind, and humidity during a hot summer period, in ENVI-met. Significant correlations are found between the morphotypes’ characteristics and local climate phenomena, highlighting the differences in performative potential between the classified urban patterns. The study suggests that the method can be used to provide insight into the systemic relations between buildings, their context, and the risk of overheating in different urban settings. Finally, the study highlights the relevance of advanced mapping and modelling tools to inform spatial planning and mitigation strategies to reduce the risk of urban overheating.
@en

Rapid urbanization and densification processes are changing microclimatic environments in cities around the world. Even though previous studies have demonstrated the impact of urban microclimate on space cooling and heating demand, modeling tools employed to support the design process largely overlook microclimatic conditions in assessing building energy performance, making use of data from weather stations often located in rural areas. This paper presents a computational approach for the quantitative analysis of building energy demand at the district scale, including interdependent factors such as local air temperature, relative humidity and wind speed, diversity in building geometry and materials. The method, which couples the microclimate model ENVI-met and the district-scale energy simulation tool City Energy Analyst, is applied to a case study in Zurich, Switzerland, in order to analyze the energy performance of the area on a hot summer day. The study contributes to advance a coupling approach between a microclimate simulation and an energy tool at the district scale. The results showed that the coupled assessment approach can deal with complex interactions between geometry, building materials and energy systems. The consideration of local microclimatic conditions led to a 5% increase in the space cooling demand on the selected day, while the simulated peak cooling load for each building was 8% higher on average. The variation in the space cooling demand was found to be mainly due to an increase in latent cooling demand. Moreover, the coupling method allowed a detailed analysis of energy demand variation at the building level showing that, when considering the local climate patterns, the space cooling demand of the individual buildings varied between −5% and +14% on the selected day. The proposed method represents a next step to reflect the mutual interactions between buildings and microclimate in urban districts and aims at supporting decision-making in the design process.@en

In the design practice simulation methods are already widely used to support the understanding of energy performance and to help designers in reducing energy demand during the design process. However, energy simulation tools are largely limited to the individual building level, and urban microclimate conditions and
variations in local wind, solar radiation, and air temperature patterns in which buildings express their energy performance are largely overlooked. In order to include microclimatic data in the computation of space cooling and heating consumption and enlarge the scale of analysis from single buildings to district scale, a new simulation method has been developed. The proposed coupling procedure links the microclimate software ENVI-met and the City Energy Analyst energy simulation tool and it is employed in the energy assessment of a urban re-development project in the city of Zurich, Switzerland. The results show that, considering microclimatic boundary conditions, the average hourly energy loads vary for daytime and night-time peaks and moreover a variation can be noticed in terms of total space heating and cooling consumption on the hottest and coldest day of a typical year.@en

The urban heat island is especially challenging in the Netherlands and other northern European countries, which are experiencing higher temperatures due to climate change. This chapter explores the effects of climate change for the urban environment and provides tools for urban design and strategies for implementation. It gives an introduction of the problem field and a climate change effect, and presents a review of climate adaptation measures. Researchers at the Delft University of Technology in the Netherlands led by Laura Kleerekoper explore implementation strategies for Dutch cities that are applicable in similar climate zones. The strategies are grouped into four broad categories: vegetation, water, built form, and materials. Influencing the built form of a city from a policy standpoint is rather difficult and more using climatic parameters. The chapter discusses a case study to apply these implementation strategies to redesign an existing neighbourhood in Utrecht that is vulnerable to higher temperatures.@en

The climate of a city influences the ways in which its outdoor spaces are used. Especially public spaces intended for use by pedestrians and cyclists, such as parks, squares, residential and shopping streets, and foot- and cycle-paths will be used and enjoyed more frequently when they have a comfortable and healthy climate. Due to a predicted global temperature rise, the climate is likely to be more uncomfortable in the Netherlands, especially in summer, when an increase in heat stress is expected. As the phenomenon of urban heat islands (UHI) aggravates heat stresses, the effects will be more severe in urban environments. Since the spatial characteristics of a city influence its climate, urban design can be deployed to mitigate the combined effects of climate change and UHI's. This paper explores these effects and tries to provide tools for urban design and strategies for implementation. Consequently, the applicability of the design tools is tested in a design for two existing Dutch neighbourhoods.@en

The study presented in this paper is part of a PhD research titled 'Comfortable and Healthy Urban Environments'. This PhD research aims at gaining insight into the relationship between building densities, building patterns, building types on the one hand and the main aspects of the physical urban climate on the other hand: penetration of daylight, solar irradiation of façades and outdoor spaces, wind, air temperature, air quality and (traffic) noise. The research focuses on the first stages of urban design since the decisions regarding urban geometry in those early stages are of great influence on the urban climate in the final design. The urban tissue is therefore reduced to its basic geometries. In this way the conditions for the outdoor climate as well as the base conditions for the indoor climate (at the position of the façade) can be studied. This paper reports on studies into daylight and wind comfort aspects. The research shows that building densities have quite an influence on daylight access and the wind climate within the street. Within a fixed density the choice of building type also has a significant influence.@en