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Line 106: − − <p>In many proprietary systems the default option for planting medium will be a granular material with very low organic matter content. However, many companies can arrange for a high organic content alternative to be substituted if requested. + − The benefits of 'high organic' media are: − <ol> − <li>Increased water holding capacity, which benefits both vegetation health and stormwater retention, </li> − <li>Often lighter weight, even when saturated, </li> − </ol> − The disadvantages of a 'high organic' planting medium are: − <ol> − <li> Increased [[Water Quality#Phosphorous|phosphorous]] concentration in runoff water, however this may be mitigated by the reduced runoff volume resulting in a lower loading overall,</li> − <li>The lightweight material is more prone to wind erosion, and this should be accounted for in the initial design, alternatives include erosion control blankets, soil tackifiers, or Sedum mats. </li> − </ol> − Increasing the depth of planting medium from 10 cm to 15 cm has been shown to benefit the vegetation[http://www.sciencedirect.com/science/article/pii/S0301479713006051]. Stormwater retention was not improved with this increase in depth[http://ascelibrary.org/doi/abs/10.1061/(ASCE)HE.1943-5584.0001534]. </p>
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<h4>Filter Layer</h4>
<h4>Filter Layer</h4>
<p>The geotextile layer is included to prevent migration of the planting medium into the drainage layer. Current advice is to specify a free draining textile to prevent potential water-logging of the planting medium. Observations green roof assemblies have shown a reduction of flow from specifications owing to interactions of medium particles with the textile.</p>
<p>The geotextile layer is included to prevent migration of the planting medium into the drainage layer. Current advice is to specify a free draining textile to prevent potential water-logging of the planting medium. Observations green roof assemblies have shown a reduction of flow from specifications owing to interactions of medium particles with the textile.</p>
<h4>Planting Medium</h4>
<h4>Planting Medium</h4>
{{:Green_roof_media}}
<h4>Irrigation</h4>
<h4>Irrigation</h4>
<p>Regular irrigation has been shown to substantially reduce the stormwater capture benefit of an extensive green roof[http://ascelibrary.org/doi/abs/10.1061/(ASCE)HE.1943-5584.0001534]. One way to reduce the irrigation used on green roofs is through the use of electronic technologies. Responsive sensors that suppress irrigation after a rainstorm are routinely attached to green roofs to conserve water. Improvements can be made by instead using a 'soil' moisture sensor to trigger irrigation. State-of-the-art management systems now use predicted weather data to prevent irrigation ahead of storm events[https://optirtc.com/products].
<p>Regular irrigation has been shown to substantially reduce the stormwater capture benefit of an extensive green roof[http://ascelibrary.org/doi/abs/10.1061/(ASCE)HE.1943-5584.0001534]. One way to reduce the irrigation used on green roofs is through the use of electronic technologies. Responsive sensors that suppress irrigation after a rainstorm are routinely attached to green roofs to conserve water. Improvements can be made by instead using a 'soil' moisture sensor to trigger irrigation. State-of-the-art management systems now use predicted weather data to prevent irrigation ahead of storm events[https://optirtc.com/products].