Roof top is a green oasis
Green roofs are created to reduce the ecological footprint of buildings.
Like all green roofs, the Chicago City Hall rooftop garden improves air quality, conserves energy, reduces stormwater runoff and helps lessen the urban heat island effect. The garden's plants reflect heat, provide shade and help cool the surrounding air through evapotranspiration, which occurs when plants secrete or "transpire" water through pores in their leaves. The water draws heat as it evaporates, cooling the air in the process. Plants also filter the air, which improves air quality by using excess carbon dioxide to produce oxygen.
The rooftop garden mitigates the urban heat island effect by replacing what was a ballasted, black tar roof with green plants. The garden absorbs less heat from the sun than the tar roof, keeping City Hall cooler in summer and requiring less energy for air conditioning. Continue reading story at City of Chicago's official site.
PHOTO THANKS TO bnicholson14 Green Rooftop at National Zoo