Tuesday, October 19, 2010

Nature Irrigated Green Roofs and Dew Catchers

Green Roof irrigation, dew and alternative irrigation has been the topic of the last several posts.

And I have come to a realization today.  I've been referring to green roofs designed as fully sustainable units requiring zero mankind provided irrigation as 'non-irrigated' green roofs.

Studying the dew catchers opened my eyes to the proper term for green roofs that do not have additional mankind provided irrigation.

'Nature irrigated green roofs' is the proper term.

Today I want to share a photo of a very effective, cheap to make and made from 100% post consumer recycled materials - Dew Catcher.

Yes, this simple dew catcher is highly effective.

A system of these dew catchers for a green roof or even an Urban Permaculture garden somewhere could save thousands and thousands of gallons of potable water from being used as irrigation water.

15 milliliters of water was collected from the dew catcher shown below on October 18th, 2010 at 8:00 am.

The dew catcher was placed on a piece of plastic wrap and set on a western exposure roof.

20 milliliters does not sound like much at first glance.  However by placing 100 of the dew catchers (no cost - only your time and effort) you would collect approximately 2000 milliliters per morning.

2000 milliliters is equivalent to approximately 1/2 gallon, so you ask - 1/2 gallon - so what?

If you place one dew catcher per square foot then a ten thousand square foot roof would harvest approximately 50 gallons of water every morning where the dew point is sufficient for harvesting.

As we mentioned in earlier blogs, cooler months facilitate the formation of dew.  Here in north Florida, as well as in many other world locations, cooler months are also the months where precipitation amounts are significantly reduced.

So just when the green roof needs additional water the most, nature provides dew.

50 gallons of irrigation water saved over hundreds of thousands of square feet of green roofs and gardens adds up to alot of water saved.  Stewardship.

And possibly the key to understanding the proper design of a self-sustaining Nature Irrigated Green Roof.

So here is the photo.

Urban Permaculture Dew Catcher - Irrigation for Green Roofs
Basic design is the top cut off of a plastic water bottle and slit down the side.

Arguments the unstable plastic will photo-degrade and leach plastics into the roof are probably valid, however there are plenty of other UV stabilized PPE's that would work just as well.

Recycled glass is another option as well as certain fabrics.

The important issue to remember though is that with a little ingenuity we can harvest air laden humidity and create sustainable irrigation systems if we choose.

50 gallons per day on a 10,000 SF roof offers 15,000 gallons per year potential.

Dew Catchers - Nature Irrigated Green Roofs!

As always, Email us with your questions here.

Happy Green Roofing!


1 comment:

Anonymous said...

Interesting. No shortage of bottles available to use, but how do you position the catcher?