This paper discusses the effects of urban design and meteorological parameters on thermal comfort for pedestrians at street level. A comparison of different urban modifications allows an objective assessment of the effectiveness of climate adaptation measures. Because, these results are based on different measurement and modelling methods, they are given in various comfort indicators and studied in a specific urban context, climate and weather condition. This study presents the relative effects of design measures based on identical input parameters and one simulation method using the high resolution three-dimensional model ENVI-met and the thermal comfort index physiological equivalent temperature (PET).

Climate change will lead to more warm and hot days in the Netherlands. Climate adaptation measures are needed to reduce the vulnerability of urban areas. Moreover, proven adaptation measures, such as increased vegetated areas or water surfaces, are not always possible due to a lack of space or undesired aesthetic effects. An alternative option is to make use of coloured façades to create drafts and accelerate wind speed in a street canyon or on a square to attract fresh air from cooler places. Differences in colour and material types already influence the air flow in street canyons in an uncontrolled manner. If this thermal comfort principle can be implemented, it will potentially have a significant impact on many cities throughout the world. This paper presents the results of a first exploratory research based on measurements on scale models and at full scale. This pilot study indicates success of the intended draft principle, advocating further research.