Clever and cool Generating design guidelines for climate-responsive urban green infrastructure

Samenvatting (Engelstalig)

Urban heat problems due to global climate change and urbanization may pose a serious risk to thermal comfort related public health in cities. Urban green infrastructure (UGI), such as parks, gardens and street trees, has the ability to alleviate urban heat and improve residents’ thermal comfort during warm summer days. Research in the field of urban micrometeorology delivers insights into the impacts of UGI on objective thermal conditions. Yet, this knowledge lacks insights into impacts of UGI on people’s subjective thermo-spatial perception and does not match the demand of spatially explicit information by urban designers. Consequently, urban designers lack guidance in the design of climate-responsive UGI in outdoor urban spaces.

The development of a spatially explicit evidence of subjective and objective impacts of UGI on thermal comfort, and based on that evidence the subsequent development of useful design guidelines for climate-responsive UGI, were the objectives of this thesis. The research approach consisted of two phases: The ‘Research for Design’ approach, a combination of qualitative (surveys, observations) and quantitative (micrometeorological measurements) research methods, delivered scientific evidence needed to inform climate-responsive urban design. A set of multiscale case studies was conducted during warm summer periods in the moderate climate of the Netherlands. In a subsequent participatory ‘Research through Designing’ approach the novel scientific evidence was translated into preliminary design guidelines, and applied in practical design settings with landscape architects. Observations, plan analysis and questionnaires provided insights into the usefulness of the guidelines for end-users and directed the refinement into revised design guidelines for climate-responsive UGI.

‘Clever and cool’ urban green can be achieved by implementing the design guidelines for climate-responsive UGI. Findings of the first phase demonstrate that UGI enhances residents’ subjective thermal perception and improves thermal conditions in urban environments. This phase provides spatially-explicit evidence of UGI relevant for design. It furthermore shows the importance of residents’ physical adaptation in the context of thermal perception. The second phase delivered evidence-based, generally applicable design guidelines for climate-responsive UGI that are accompanied by visual representations. Additionally operational principles to support site-specific implementation of the guidelines at the respective scales. The practical design settings furthermore showed that urban designers need a basic understanding of microclimate processes and skills to conduct microclimate analysis to appropriately  implement the guidelines. Concluding, this thesis argues for climate-responsive UGI that is ‘clever and cool’: UGI that is designed resource efficiently, is based on site-specific microclimate analysis, and considers spatial conditions as well as the behavioural demands of urban dwellers. Through combining perspectives and knowledge of microclimate science and design practice this thesis provides evidence-based solutions that are considered useful by end-users. As such the design guidelines for climate-responsive UGI, as presented in this thesis, can enhance urban design practice for more thermally comfortable and liveable cities now and in the future.