Digitalizing the urban landscape. Microclimate, energy systems and comfort

Urban Green Infrastructures (UGI) play a major role in mitigating the urban climatic conditions, as well as improving people’s health and wellbeing. Indeed, nature has a positive impact both on the pedestrian thermal and psychological perception, increasing productivity and creativity due to their restorative properties. Additionally, UGI mitigate the urban climatic conditions, reducing the energy demand of buildings and affecting the energy systems. The objective of this work is to develop a digital platform to arrive at urban planning decisions considering the impact of greenings on the urban microclimates, thermal perception of the pedestrians and energy infrastructure. The greening module developed within the tool CitySim [1] is coupled with the Canopy Interface Model [2], in order to compute the impact of greening (trees and grass) on the air temperature and wind speed. The study is performed for several urban configurations, focusing on the Lausanne climatic conditions. Greenings are designed as grass (varying their f-factor as function of the water supply), and trees (varying their leaf area index and height). The microclimatic conditions are used to quantify the hourly human thermal comfort, by the bio-meteorological index COMFA* budget. The proposed methodology also integrates energy systems optimizations [3], focusing on the impact of greenings on the renewable energy systems and its influence in smoothing the peak demand. The simulations performed provide the dynamic hourly variation of the wind speed and air temperature within the urban canyon, as function of the greening design (evapotranspiration capacity, geometrical properties of trees). The human thermal comfort is computed, in time and space, showing the positive impact of greening in reducing the “warm” and “hot” thermal sensations during the warmer months. The hourly energy demand of buildings is also computed, and the results are analysed focusing on the renewable energy systems. Results indicate the positive impact of greening in mitigating the urban climatic conditions, as function of the canyon design and the evapotranspiration capacity of the landscape. The important impact on the energy demand of buildings and the energy systems is also presented, providing recommendations for a smart urban systems design. The proposed digital platform provides an interactive display, a common ground of discussion for urban planners, architects, engineers and biometeorologists. Thanks to the work developed, an interdisciplinary knowledge is defined, which will be used as a teaching instrument within the ENAC faculty.