The Thermal and Rainwater Runoff Performance of an Extensive ...
The Thermal and Rainwater Runoff Performance of an Extensive ...
The Thermal and Rainwater Runoff Performance of an Extensive ...
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1 Introduction1.1 Green Ro<strong>of</strong> DefinitionA green ro<strong>of</strong> (also known as <strong>an</strong> eco-ro<strong>of</strong>, nature ro<strong>of</strong>, living ro<strong>of</strong> or ro<strong>of</strong> greening system) is aliving, vegetative system that contains a substrate (growing media) <strong><strong>an</strong>d</strong> a vegetation layer atits outermost surface [1]. <strong>The</strong> design <strong><strong>an</strong>d</strong> construction between the ro<strong>of</strong> structure <strong><strong>an</strong>d</strong> thegrowing media varies, but typically includes a geo-textile filter, drainage layer, root barrier<strong><strong>an</strong>d</strong> a waterpro<strong>of</strong> membr<strong>an</strong>e. Depending upon the vegetation layer, the growing media depthc<strong>an</strong> vary from 20mm (for extensive systems utilising sedum mats) to 1500mm (for intensivesystems containing large shrubs <strong><strong>an</strong>d</strong> trees).1.2 Background<strong>The</strong> concept <strong>of</strong> the green ro<strong>of</strong> is not a new phenomena; with its basic functionality beingutilised for several centuries. More recently, increasing urb<strong>an</strong>isation <strong><strong>an</strong>d</strong> the encroachment <strong>of</strong>‘urb<strong>an</strong> sprawl’ on to green belt areas has led to a ‘greying’ <strong>of</strong> the l<strong><strong>an</strong>d</strong>scape <strong><strong>an</strong>d</strong> a reduction inamenable space. <strong>The</strong> increase in urb<strong>an</strong> density in order to reduce this urb<strong>an</strong> sprawl <strong><strong>an</strong>d</strong> theresulting loss in geographical identity - along with increasing environmental awareness - hasincreased the awareness <strong>of</strong> the adv<strong>an</strong>tages that green ro<strong>of</strong>s c<strong>an</strong> bring.Green ro<strong>of</strong> systems c<strong>an</strong> provide a number <strong>of</strong> adv<strong>an</strong>tages, r<strong>an</strong>ging from the associatedenvironmental <strong><strong>an</strong>d</strong> ecological issues, through to the aesthetic impact <strong>of</strong> new <strong><strong>an</strong>d</strong> existingdevelopment. <strong>The</strong>y c<strong>an</strong> be used as a way <strong>of</strong> compensating for increased urb<strong>an</strong> density –providing a visual <strong><strong>an</strong>d</strong> recreational escape from the ‘concrete jungles’ <strong>of</strong> urb<strong>an</strong> l<strong><strong>an</strong>d</strong>scapes.<strong>The</strong>y c<strong>an</strong> also allow rural buildings to blend in with their surroundings – <strong>an</strong> import<strong>an</strong>t benefitespecially in areas <strong>of</strong> natural scenic beauty.M<strong>an</strong>y Europe<strong>an</strong> countries have already acknowledged the related benefits <strong>of</strong> green ro<strong>of</strong>s. InGerm<strong>an</strong>y, government legislation <strong><strong>an</strong>d</strong> fiscal incentive encourages their widespread use. Thishas resulted in over 80 million m 2 <strong>of</strong> green ro<strong>of</strong>s, compared with only 1 million m 2 in the UK[2].Niall Carroll Page 13<strong>The</strong> <strong>The</strong>rmal <strong><strong>an</strong>d</strong> <strong>Rainwater</strong> <strong>Run<strong>of</strong>f</strong> <strong>Perform<strong>an</strong>ce</strong> <strong>of</strong> <strong>an</strong> <strong>Extensive</strong> Green Ro<strong>of</strong> System
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