Green roof growing medium is composed of mineral aggregates and only a small amount of organic material.
Water retention for tradiotnal roof vs green roof.
Note that there was very little if any runoff during the may 1 to sept 30 growing season.
Manufacturers whose materials we use for landscape works are well known all over the world.
Drainage and water retention elements with low medium or high retention capacity are components of the green roof system.
2009 analyze the joint effect of green areas in new york city using a meterological regional scale model and conclude that in terms of direct effects on energy high albedo roofs would be a better way.
However a purple roof retains more water than any other green roof concept.
Data collected from a study by researchers at the pennsylvania state university center for green roof research show that green roofs captured up to 80 of rainfall during rainstorms compared to 24 typical for standard roofs.
The control flow roof drain insert should be even to the lowest point of the green roof installation the water will not exceed 3 5 in height.
Traditional soil is heavy and packs tight after repeated rains reducing water retention and aeration for plant roots.
The secret of green roof water retention is green.
At 3 5 maximum water depth roofblue provides up to 455 cubic inches approximately 2 gallons or 7 4 litres of water detention per square foot.
We need to think differently about the main purpose of a green roof.
Green roofs typically provide stormwater retention as they capture water preventing water from draining and then allow the water to evaporate only through evapotranspiraton processes.
Figure 2 shows the daily rain and associated daily green roof runoff for 1993 in state college pa for a green roof having a maximum of 1 6 inches of water retention storage.
This means that the water leaves the roof as vapor.
As green roof plants mature and root systems grow storm water retention may increase.
However retention is not always effective as it fills up the entire empty storage space in green roofs and then takes time to dry out and make room for new.
For water retention performance we monitored runoff from four full scale green roofs including one built up system one modular tray system and two vegetated mat systems.
Rain falls onto a relatively dry green roof and the green roof absorbs the water usually in pore spaces later the sun comes out and the plants use the rainwater to evapotranspire.
We already had some common projects and results were reliable and spectacular.
Retention works like this.
Green roofs are suggested as one of the potential solutions of adapting cities to climate change and as a means to cool urban areas rosenzweig et al 2009 rosenzweig et al.
