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Courtesy of The Green Institute - Minneapolis, MN <br />KEY CONSIDERATIONS <br />Design Criteria: <br />► Structural load capacity, how much weight <br />the roof can hold, is a major factor in <br />determining whether the green roof is <br />"extensive" or "intensive" (see next page). <br />► Vegetation selection is based on numerous <br />factors including, growth medium depth, <br />microclirnate, irrigation availability and <br />maintenance. <br />► A leak detection system is recommended to <br />quickly detect and locate leaks. <br />► Modular products can increase installation <br />and repair efficiency. <br />Benefits: <br />► Reduce, delay, and cool stormwater runoff- <br />► Insulate buildings and lower energy <br />consumption and costs. <br />► Provide habitat for birds and insects. <br />► Increase longevity of traditional roofing <br />systems by protecting from ultraviolet rays. <br />► Reduce carbon dioxide levels and heat <br />island effect. <br />Limitations: <br />► Cost is higher than traditional roofing <br />systems — can be significant for retrofits. <br />► Leaks can cause significant damage and <br />can be hard to locate and repair without an <br />electronic leak detection system. <br />► Conditions can be harsh for vegetation <br />establishment. <br />► Maintenance needs can be higher than <br />traditional roofing system. <br />GREEN ROOFS <br />Definition: <br />Green roofs consist of a series of <br />layers that create an environment <br />suitable for plant growth without <br />damaging the underlying roof system. <br />Green roofs create green space for <br />public benefit, energy efficiency, and <br />stormwater retention/ detention. <br />1-F!J11 Water Quality (V,Itl) <br />btud. Channel Protection (V�,,) <br />I ow Civerbank Flood Protection (V t,10 <br />Low Extreme Flood Protection (V ptuu) <br />i. Recharge Volume (Re„) <br />Infiltration '�'rnn agfl.nnnalr. soa ;i rundaiana <br />Screening/ Filtration <br />z Temperature Control <br />Settling <br />Evaporation <br />Transpiration <br />Soil Adsorption <br />Biological/ Micro. Uptake <br />Total Suspended Solids <br />Note: Pollution removal percentages apply to volume of runoff treated, <br />Nutrients - Total Phosphorus: <br />Total Nitrogen <br />Metals- Cadmium, Copper, t -easel, <br />4- <br />and Zinc <br />F $ ar <br />Pathogens- Coliform, Streptococci, <br />E. Coli <br />z <br />. .r - <br />Toxins - Chloride, Hydrocarbons <br />Pesticides <br />Note: Pollution removal percentages apply to volume of runoff treated, <br />