The world is increasingly being urbanised. We all realize that this is how we are going to live so it better be a good place – and ecological too.
One factor contributing to urban wellbeing – and in many ways – is green city surfaces. They are the home of plants and if properly made they absorb excess water, delay the flow of water and relieve drainage systems.
Green roofs are increasingly seen as a resource in this respect. Urban planners design the roofs so they can absorb massive amounts of water, have plants and be used as paths and for various activities. Heavy roofs may have load capacity of 900 kg/m2, and sizes are in the tens of thousands of square meters, the biggest in Northern Europe being 28000 m2. Watering and fertilizing is normally sparse.
Green roofs regulate temperature, making it lower in summer and higher in winter. A study in Chicago has shown enormous cost savings related to cooling costs in summer. There are also health effects as greenery absorbs gases, influence particle flow, cleans the air, takes away CO2, NOx.
Many countries now have incentives and requirements related to green roofs: Canada, US, many European countries, some are aiming at quite high percentages of green roofs in cities. The EU has subsidies in place to encourage green building.
Rain gardens are also being built, and their main job is to delay water flow.
So watch out: green urban environments are spreading – maybe they are coming to a place near you? What about growing crops on these roofs in the cities?
