Why Green Roofs?
· Green roofs (also know as living roofs) have proven to mitigate stormwater runoff from urban areas, such as the UVM campus. As stormwater moves through the roof’s growing media, microorganisms and plant roots sequester impurities from the water.
· Water that comes off green roofs is less polluted than water that moves across impervious surfaces and into lake Champlain
· Green roofs can also provide natural insulation for a building and can therefore help reduce heating an cooling costs.
· Green roofs add natural beauty to urban landscapes.
Extensive Green Roof
(Thin growing medium; little or no irrigation; stressful conditions for plants; low plant diversity.)
· Lightweight; roof generally does not require reinforcement.
· Suitable for large areas.
· Suitable for roofs with 0-30 deg. Slope.
· Low maintenance and long life.
· Often no need for irrigation and specialized drainage systems.
· Less technical expertise needed.
· Often suitable for retrofit projects.
· Can leave vegetation to grow spontaneously.
· Relatively inexpensive.
· Looks more natural.
· Easier for planning authority to demand as a condition of planning approvals.
· Less energy efficient and storm water retention benefits.
· More limited choice of plants.
· Usually no access for recreation or other use
· Unattractive to some especially in winter.
Intensive Green Roof
(Deep soil; irrigation system; more favorable conditions for plants; high plant diversity; often accessible.)
· Greater diversity of plants and habitats.
· Good insulation properties
· Can simulates a wildlife garden on the ground.
· Can be made very attractive visually.
· Often accessible, with more diverse utilization of the roof. i.e. for recreation, growing food, or as open space.
· More energy efficiency and storm water retention capability.
· Longer membrane life.
· Greater weight loading on roof
· Need for irrigation and drainage systems requiring energy, water, materials.
· Higher capital & maintenance cost.
· More complex system and expertise.
Our Project Goals
· Demonstrate alternatives for implementation on UVM’s campus
· Portable design for classroom use
· Data collections to assist UVM planners in selecting most appropriate green roof design
· Provide information and hand-on learning to educate visitors
· Generate excitement and support for green roof system implementation on existing and future UVM buildings
Two Major Classes of Green Roofs