What is a green roof?
The term includes a wide range of solutions, from a thin layer of sedum plants to parks on roofs with bushes and trees. Using plants on ceilings can be traced far back in human history. The most well-known example is the “Babylon’s Hanging Gardens”, one of the seven wonders of ancient times. In the north, green roofs have a long tradition on many Scandinavian buildings but disappeared from the towns during the 19th century. It was not until the end of the 20th century that green roofs became popular. Now they are widely used as a method for a sustainable and more climate adapted urban development.
Green roof benefits
There are many benefits from green roofs, especially in an dense urban setting.
The ecological benefits of green roofs are that they create conditions for a richer flora and fauna in the city and thus have a positive impact on biodiversity. It is possible to replicate natural habitats on the roof with plant communities that have not previously existed in the city. Common animals on green roofs are various invertebrates and important bees, such as bumble bees, bees, spiders, butterflies, beetles and hoverflies, as well as some birds.
Gröna tak både fördröjer och minskar mängden regnvatten som rinner av från tak vilket minskar trycket på stadens dagvattensystem. Studier visar att gröna tak kan reducera den årliga avrinningen med 40-90% beroende på hur tjock växtbädden är. Idag ökar intresset kring att anlägga gröna tak som en klimatanpassningsåtgärd och det finns flera olika lösningar på marknaden som är särskilt utformande för att också drastiskt minska avrinningen vid skyfall.
A green roof reflects more sun rays than roofs with dark waterproofing and evaporation from green roofs also contributes to lower surface temperatures. It can in some cases have a positive impact on the need for air conditioning inside the building and the city's climate. A common roof sealing layer is often vulnerable to UV light and rapid temperature changes. A green roof protects the sealing layer and extends its life considerably.
Several studies show that we humans feel better when we have a lot of greenery around us. Green roofs are a way to increase the vegetation on surfaces that are otherwise usually hard and gray. Being able to look out on a green roof or using roofs for parks and gardens has a calming and health-promoting effect. The green roof's plant bed and vegetation also reduce the noise level, which also contributes to increased well-being. The noise-canceling effect increases the deeper the plant bed is.