Evaporative cooling strategies in urban areas: The potential of vertical greening systems to reduce nocturnal heat stress

Abstract

This research is part of a project that aims to create a simulation workflow to design adaptive facades to not only reduce the energy demand of buildings and provide a good level of indoor comfort. but also to mitigate the urban heat island effect. The anthropogenic climate change results in a steady increase of hot days. tropical nights and heavy rainfall. affecting the quality of human comfort. especially in urban areas not only in hot regions of the world but also in Central Europe. Vertical greening systems are often a first-choice mitigation strategy to improve the deteriorating situation. By combining the use of natural resources like rainwater and solar radiation. the greening evaporates water and provides natural cooling. This paper deals with the efficiency and feasibility of vertical greening systems towards a relief in heat stress by simulating different constructions under local circumstances of three climate zones. focusing on the night-time. To carry out the simulations with microclimate simulation tool ENVI-met. an urban apartment complex was designed and provided with different kinds of vertical greening to investigate the various positive effects resulting from the green façade. As a shading device. the greened walls showed a significant decrease of wall surface temperatures of up to 18K. However. restricted transpiration fluxes obstruct exploiting the full potential of evaporative cooling. especially during night-time.