Green roofs improve air and water quality while reducing energy cost. The implementation of green roofs in some regions have correlated with increased albedo, providing slightly cooler temperatures and thus, lower energy consumption.The plants and soil provide more green space and insulation on roofs. Green and blue roofs also help reducing city runoff by retaining rainfall providing a potential solution for the stormwater management in highly concentrated urban areas. The social benefit of green roofs is the rooftop agriculture for the residents.
Green roofs also sequester rain and carbon pollution. Forty to eighty percent of the total volume of rain that falls on green roofs are able to be reserved. The water released from the roofs flow at a slow pace, reducing the amount of runoff entering the watershed at once.
Blue roofs, not technically being green infrastructure, collect and store rainfall, reducing the inrush of runoff water into sewer systems. Blue roofs use detention ponds, or detention basins, for collecting the rainfall before it gets drained into waterways and sewers at a controlled rate. As well as saving energy by reducing cooling expenses, blue roofs reduce the urban heat island effect when coupled with reflective roofing material.