A beneficial way of helping our cities to adapt and mitigate the effects of climate change is utilising green space. Green roofs are and will be an increasingly important technology. The ecosystems services that are provided by green roofs will be especially significant in regard to a reduction in the Urban Heat Island Effect (our summers are predicted to get much hotter).They will also help to decrease the impact of flash summer storms that are predicted to increase as the climate changes. In this article I highlight the benefits of establishing a green roof.

Green Roof - Living Roof

According to researchers in Tyndale Centre for climate change, a 10% increase in green space in our cities would probably fight the negative effects of climate change and minimise the Urban Heat Island Effect [UHIE].

On the same time a big number of researches in Switzerland and the UK support that many rare invertebrate populations and wild bird species can find refuges in these green terraces.

An average green roof can absorb directly up to 75% of the rainfall, while 60% of cadmium, copper and iron are removed from the rain water, if they pass through the vegetation. As a source control mechanism in the Sustainable Urban Drainage System green roofs can help minimise flash floods as a consequence of intense rainfall events. This will become increasingly important as a consequence of climate change.

Green roofs cannot be given a U-value at present. However it is proved that they significantly decrease the need for air conditioning in summer and can provide a degree of insulation in winter.

Having a green rooftop will provide you better health levels and mental wellness, because it will reduce city noise by 10dB up to 50dB according to calculations. The range depends on the thickness of the culture medium and the type of implementation. The growing medium seems to block lower sound frequencies whilst the plants block higher frequencies.

The original green roofs in Germany stem from covering wet roofing tar with 6 cm of sand, which became vegetated. This covering was to protect the wet tar from fire. Green roofs have shown to double if not triple the life of waterproofing membranes beneath the green roof. During the summer, depending on the vegetation, a green roof can retain 70-90% of rain, while in winter between 25-40%. E.g. a roof with thickness planting of 4-20cm, can hold 10-15cm water.

A well- designed green roof can also filter atmospheric airborne particles and pollutants up to 80%. Plants absorb them and throug photosynthesis produce oxygen.

From another point of view, a green terrace will also upgrade the quality of your social life. By giving right direct access to roofs for all residents, sociality will be encouraged.

There are also many economic benefits. A green roof will lower the costs for air conditioning and maintenance, increase property value and provide economical functioning of the sewer system. The cost to cover the roof with greenery ranges (average values) on 80 € / m2 (extensive type), 95 € / m² (semi-intensive type) and 120 € / m² (intensive type). However the payback of a green roof through the savings from central heating and air conditioning costs is estimated at 2-3 years.

Considering all the above advantages of green roof we conclude to the fact that green infrastructure is a clever and easy way to fight climate change and at the same time a very creative hobby.


Photocatalysis Industrial Association of Japan (PIAJ)


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