Greening the city

Urban heat islands (UHIs) have become a well-known issue in built-up areas of large cities. A recent study shows that temperatures in UHIs are on average 5⁰C higher than in surrounding areas. Since a growing proportion of the population in industrialised countries now live in cities, this effect leads to discomfort and even death especially with the elderly people.

Inhabitants of metropolitan areas have begun demanding action against the overheating of concrete jungles. They call for “more shade” to be produced mainly by tree canopies of freshly planted trees.

Due to growing bottom-up pressure by citizen groups, activists, and the media, the City of Vienna developed an initiative (2011-2014) to reduce urban warming. Following this, Vienna compiled an Urban Heat Island Strategic Plan in 2015. It lays out the nature protection and levels of action in favour of a climate sensitive urban planning.

Among the remedies suggested by the strategic plan is the extension of vertical gardens and roof gardens. Public buildings, including schools, are the main target of these measures. However, experts concede there is much room for pushing this further, and that promoting single showcases in the media isn’t alleviating the overall urban heat development. As much as the strategic plan is well-intended, and the recommendations in it are sensible, the execution of these actions is lagging far behind the current climate changes that we experience.

Figure 1. Vertical garden at the Aqua Terra Zoo in Vienna

Figure 2. Vertical garden Madrid