In 2014, the United Nations Department of Economic and Social Affairs announced that the majority of humans were residing in urban environments for the first time in recorded history. As the world’s population centers become more densely urbanized, average temperatures in these areas are on the rise. The Urban Heat Island (UHI) effect can be felt on any typical hot and sunny day in cities like Los Angeles or Washington, D.C. In the middle of the city, concrete highways and structures absorb UV rays from the sun and radiate heat into the surrounding area. If you were to venture outside of these cities to less densely populated rural areas, you may find temperatures up to 27℉ lower.
This vast increase in temperature isn’t only an issue while the sun is out. Nighttime temperatures in urban areas have been found to be as much as 22℉ higher than air temperatures in neighboring, less developed areas. The UHI effect is exacerbated by removing green spaces, which leads to an increase in greenhouse gas emissions and air pollution levels. Removing green spaces puts a strain on other critical urban infrastructure such as the energy grid, water quality and public health systems. Redeveloping underutilized land, such as vacant lots or former industrial and commercial sites, presents excellent opportunities to rethink UHI mitigating factors such as the urban tree canopy, green roofs, and other issues related to site design and building materials. Land recycling presents an opportunity to design from the ground up in anticipation of the our changing climate and the demands it will place on all of us.