Green Roof Seminar
Green Roof and Cool Roof Seminar
These are notes from a lunch and learn seminar about Green Roofs.
If a typical roof costs around $7 per sf, a green roof will cost you between $20 and $40 a square foot. This makes the payoff stretch to roughly 10-14 years.
Green Roofs can give you a 15-20 dB sound reduction. The soil reduces the low frequency sounds, and the plantings reduces the high frequency sounds. There was an interesting application at an airport.
Sinlge Ply membrane Roofing beneath a green roof is not a good idea because of the abrasion of the soil, and the traffic necessary to install the roof.
Layers from the top down – plant, soil, root barrier and capilary drainage layer, built up membrane roof, concrete.
Calculate where the dew point occurs in the roof layers to ensure that condensation doesn’t accumulate in an undesired location.
Testing shows black roof is 160 degrees in 90 degree weather, and green roof is 95 degrees on the same 90 day.
Trays are 10% more expensive than a regular soil and plant install, but the cost of labor goes down because installation is easier. Local Source for these is GRO – Green Roof Outfitters
30% of the cost comes from material, 70% comes from labor.
Engineered Soil is lighter and holds more water, and it can use recycled post industrial waste.
Grasses and Seadums are most common planting.
Seadum applications can happen on up to a 40% sloped roof
Cool Roof has to do with solar roof index which combines reflectance and emissivity. Coolroof.org is a good source for information.
SRI is the Solar Roof Index
An Inverter converts 75 to 80 percent of energy from DC to AC
New Thincell Panels are Solar Panels that require less light to produce energy. Product Manufacturer: Unicell
The New Federal Stimulus Package gives money for installing solar cells and covers the roof beneath them also.
Solar Roof Installation comes in around $40 per sf.
Payback is not great for small residential scale.
The Solar Cells can be tied back into the power grid and offset the cost of power.