If you live near a park you know that even a small amount of nature can cool the local environment, and you know that the bigger the park the more cool it is. In terms of a land-to-cooling-effect ratio certain types of parks are more efficient than others with the clear winner being a botanical garden. A simple playground with some trees can cool the local area by 2.9 degrees, a green roof can cool areas by 4.1 degrees, botanical gardens reduce outdoor temperature by 4.9 degrees! Any natural spaces can cool your neighbourhood so this summer get out there, plant some plants, and make your city a cooler place.
From a pool of more than 27,000 research papers, the researchers selected 202 for meta-analysis based on a number of urban green-blue-grey infrastructure categories – including parks, engineered greening projects, wetlands, green walls, parks and botanical gardens.
Trees and plants, for example, help reduce heat by reducing the amount of direct sunlight reaching the ground, while also releasing moisture into the air. Water bodies cool the surrounding environment via “evapotranspiration, shading, the albedo effect, groundwater recharge and temperature buffering” and could also serve as heatsinks, cooling during daylight hours and offering warming potential at night. Green roofs and walls not only help insulate buildings, but also reduce heat absorption, and vegetation can serve as windbreaks for natural ventilation.