Multiple Choice, Multiple Answers

Read the passage and select ALL statements it supports.

As cities expand, planners are increasingly turning to green roofs, where a layer of soil and hardy plants is grown on top of buildings. These living surfaces absorb rainwater that would otherwise rush into overloaded drains, easing the risk of flash floods after heavy storms. The plants also cool the air through evaporation, helping to counter the way concrete and asphalt trap heat in dense neighbourhoods. In addition, a green roof can shelter the building beneath from temperature swings, trimming the energy needed for heating and cooling. The main drawback is the extra weight, which means many older structures must be reinforced before installation.