Requirements, recommendations and information for using green roofs as a BMP in the MIDS calculator Revision as of 18:58, 7 August 2013 by Mtrojan (talk | contribs) (→Model input requirements and recommendations)
Revision as of 18:58, 7 August 2013 by Mtrojan (talk | contribs) (→Model input requirements and recommendations)
This site is currently undergoing revision. For more information, open this link.
The information on green roofs will be updated in early summer of 2013
The information on green roofs will be updated in early summer of 2013
Below is a summary of requirements, recommendations and other information for using the Minimal Impacts Design Standards (MIDS) calculator for green roofs. Links to MIDS pages and the MIDS calculator are included at the bottom of this page.
Contents
Model defaults
- Media holding capacity = 0.33 cubic feet per cubic feet
- Annual volume retained = 45%
- Phosphorus reduction (particulate and dissolved) = 0%
- TSS reduction = 85%
- TSS Event Mean Concentration = 15 mg/L
For more information see the water quantity and water quality sections in the green roofs overview or the article on calculating credits for green roofs.
Model input requirements and recommendations
Caution: The following are requirements or recommendations for inputs into the MIDS calculator
- Media depth must be 4 inches or less
- The top surface area of the green roof cannot exceed the total impervious area for the site
- The contributing impervious area cannot be more than 2 times the surface area of the green roof. Since the green roof itself is treated as an impervious surface in the calculator, the maximum run-on area to a green roof from a traditional roof must be equal to or less than the area of the green roof. For example, a 10,000 square foot green roof can also have a 10,000 square foot or less run-on area from a traditional roof. In this example, the maximum impervious area input to the calculator is 20,000 square feet.
Information
Information: The following information may be useful in determining inputs for the MIDS calculator
- Information on green roof design
- Guidance on characteristics of different types of green roofs
- Information on green roof construction