Cities for Seasons - In favor of microclimate diversity as alternative to the parameter of total yearly comfort hours in competitively livable cities in temperate climates

Temperate cities compete to rank the world’s most livable, while competing under the same premise: A summer period with relatively abundant life on the streets, and a winter period with relatively sparse life on the streets, owing to cold stress. Yet these cities – Copenhagen, London, New York, Melbourne, Paris, Vancouver, Vienna – have been implementing strategies that are directly detrimental to the elongation of their streets’ active seasons: Motivated by increasingly frequent and intense heat events, they have set out to mitigate urban heat island effects, aiming to eliminate any time that any surface exceeds the upper limit of the human thermal comfort range. But with no spatial or temporal limit to these strategies and guidelines – the approach is consistently the more heat island mitigation the better – these strategies inadvertently incentivize a complete, systematic prevention of warm microclimates that, while they may be too hot during the heat waves, can be highly attractive the rest of the year. Therefore this thesis employs a tri-seasonal rhythmanalysis to explore the dynamic use of places that are subject to urban heat island effects as well as of places which are subject to cooling effects. In the terminology of the author, these places together constitute an area with “high microclimate niche development”, which stands in contrast to the areas with low niche development that are predictably reproduced when focusing on UHI mitigation, and when optimizing according to the parameter of total yearly comfort hours. It finds that when the warm niches are accessible – like at south facing ‘soft edges’ of interactive buildings – they significantly extend the local active season: That in early spring, when people first move out of the buildings, they tend to gravitate toward the warm, south facing edges of these buildings, after which a spillover effect happens from these warm niches, into adjacent cooler niches, and back, throughout the days as well as the seasons, whereby the warm niches exhibit a pulsing, gravitational pull. This descriptive model is synthesized into a prescriptive model and a series of preliminary methods of analysis, which aim to display and thereby enable assessment of microclimate diversity, and of synergy with complementary parameters. As proof of concept, these models are used to formulate re-designs. This approach is found to synergize with contemporary approaches for flood mitigation and for biodiversity, but demands one key shift: acknowledging that, in temperate cities, heat islands can play a substantial positive role. It argues that this shift appears as the logical conclusion of the development started by Jan Gehl when he defended the import of the (at the time) uniquely Mediterranean café culture to ‘cold’ northern Europe. It predicts that this shift may transform urban life in temperate cities in a similarly profound way.