Thursday, July 7, 2011

Green Roof Irrigation Opportunities, Exploring Water Vapor

Fortunately, there are many ways green roof plants can be provided irrigation water.  First we should utilize native rainfall amounts, second water vapor in the form of dew, fog and air humidity.   Air conditioning condensate can provide a significant amount of irrigation as well.  Finally, rainfall captured in rain barrels or underground storage and cistern systems may be utilized to support plant water requirements.  Grey water too may be used if local or state regulations permit.

I've always been amazed at how much water the air holds.

Several of our past blog posts have addressed dew, fog and water vapor (biomimicry).

This morning as I inspected a recent green roof project, I was awestruck at just how much water was rolling off the solar panels, dripping to the single ply roofing, running across the roof to the drip edge and into the gutters.  Alot of water!
Dew Stream Dripping from Solar Panels

So when we think of green roof design we need to visualize the advantages elevated vegetated plantings have over ground level plants from water laden air exposure.

Nature has provided many plants with fine hairs, such as one of my favorite green roof plants, Yucca filamentosa, a physiological attribute allowing for water collection.

Before we immediately specify irrigation systems with potable water for either primary or backup supply,  lets seriously look at what nature provides.

We may be surprised at just how much water nature is making available.

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