Design with Microclimate blog with permission. When Kassel University and Dr. Sanda Lenzholzer mapped the urban climate of Arnhem, Netherlands, they identified several 'hot spots'. The red splotches on the map indicate places where people would be overheated on summer days. Sanda was not satisfied with simply identifying hot spots—she wanted to do something to make them cooler. An analysis of the microclimate of these locations identified some typical urban heat island (UHI) problems: too many hard surfaces and too few trees. The red area outlined with a pink ring on the map is a densely populated area centred on the Graaf Ottoplein square (below) that is almost devoid of trees. Sanda wondered how she could get more trees growing in that neighbourhood. She also wondered if there was some way to do it while educating the public as to the microclimatic value of trees in urban areas so that they might also take action around their own houses.