Strategies:
Green Roof Components Drainage element: Recycled polyethylene Water troughs on top side hold 0.1 gallons water/s.f. Retained water is released into soil by evaporation or root uptake. Holes in tops of troughs allow for air circulation, evaporation, and ventilation of soil and roots Moisture Retention Mat: Recycled polypropylene fibers Retains 0.12 gallons water per square foot to promote root growth Growing Medium: Tailor to structural loading capacity of building pH, nutrients, porosity and water permeability needed by plants Deep enough to protect plants from frost and compaction, and have a stable structure for root anchorage Resistant to wind and water erosion Using pure native garden soil often results in problems when the soil degenerates from compaction and acidification. Plant Qualities for Extensive GR: Perennial or self-seeding plants Shallow, fibrous mat roots Require no maintenance Survive in shallow soil Provide no ambient heat Endure drought Withstand high winds Tolerate extreme sun exposure Irrigation: Irrigation is primarily for plant establishment & building cooling Temporary establishment of plants is 2-3 seasons (spring, summer, fall) Offers peak load cooling on flat roofs in summer (e.g., 1 story flat roofs) Irrigation for Plant Establishment: Plants need at minimum 1” of water per week June, July, August Pan evaporation is 2” per week June, July, August (MSP)
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