雅思听力

🎧 Listening Transcript

Today in our lecture on urban planning, we'll discuss the concept of 'green roofs.' A green roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems. Green roofs serve several purposes, such as absorbing rainwater, providing insulation, creating a habitat for wildlife, and helping to lower urban air temperatures. However, they are not suitable for all buildings. For example, older structures may not support the weight of the soil and plants. Also, initial installation costs can be high, though they may reduce energy bills in the long term.