Evaluation of comfort conditions and sustainable design of urban open spaces in Crete

The thermal environment in outdoor public spaces and their use is highly relevant to individuals' thermal comfort perception. Since climatic conditions directly affect the use and activities of outdoor spaces, they should be taken into account when designing public spaces. Especially in Southern Europe, due to the extended use of outdoor spaces during summertime where the urban heat island phenomenon is present, a more sustainable design is very critical for their viability. This present paper reveals the strong relationship between the microclimate and the outdoor comfort conditions through field surveys conducted in four different urban open spaces in Crete. Thermal indices like PMV (Predicted Mean Vote), PET (Physiologically Equivalent Temperature) and SET (Standard Effective Temperature), WBGT (Wet bulb globe temperature) are used to evaluate the assessment of urban microclimate and then are compared in order to find the most suitable for the Mediterranean microclimate. In this way every designer can simply affect the sustainability of the urban open place with the control of the microclimatic conditions into it and can easily predict the levels of comfort of his proposal. The deviations of these microclimate factors that are proved to affect the individual thermal comfort, in the Mediterranean climate of Crete, are simulated using the numerical microclimate model ENVI-met (Bruse and Fleer 1998). ENVI-met uses data from the area design, vegetation, climate, materials and translates them into microclimate maps of present and future. In this way develops the ability to the designer to evaluate with high accuracy the comfort conditions of every outdoor design and its effect on the surrounding microclimate. Field measurements on a central park of Chania one day per month validates the accuracy of the simulation using ENVI-met, afterwards several design and vegetation scenarios are tested in order to conclude in the most viable in terms of comfort solution. The aim of this study is not only to evaluate the most suitable value of every microclimatic factor for the individual perception of comfort so as to provide a specialized model of comfort in the Mediterranean areas but also to find the way for achieving the desired microclimatic conditions through a proposed sustainable design.