Living Green in the Southwest: Green Roofs?

Tempe Transportation Center

Just after I posted on Monday that white roofs really do work, Marshall Carter-Tripp sent me two links to news articles about "green roofs". Googling I quickly learned that there is a greenroofs.org as well as a greenroofs.com, the latter I just began following on Twitter.

Ecosystem Gardening touts these benefits:

1. They last up to twice as long as traditional roofs
2. They slow the progression of rain into the stormwater system
3. They mitigate urban heat island effects
4. They provide an insulating layer to buildings, keeping them warmer in winter and cooler in summer, which decreases costs related to heating and cooling
5. The vegetation absorbs carbon dioxide and produces oxygen
6. They create habitats for wildlife

Of course, I'm concerned about the effectiveness of a green roof in our desert environment and the issue of water conservation.  Altenergymag.com has this to day:

In desert communities, greenroofs can greatly enhance the residents' life quality due to their benefits:

1. greenroofs provide thermal insulation, so as to reduce cooling loads (and avoid a few of the downsides of heavy AC use, like Legionnaire's disease and thermophilic actinomycetes)
2. greenroofs provide acoustic insulation,
3. greenroofs reduce heat island effect,
4. greenroofs create wildlife habitat,
5. greenroofs absorb occurring rain water, saving drains from intermittent overloading,
6. greenroofs clean ambient air by absorbing CO2 and producing oxygen,
7. greenroofs increase the roof lifespan.

Scientific American writer, Katie Moisse, puts forth in Over the Top: Data Show "Green" Roofs Could Cool Urban Heat Islands and Boost Water Conservation that a green roof is no more expensive than a white roof and conserves water at the same time.

I'm skeptical. Green roofs must take more work. I paint my roof white and I'm done. I have a green roof and I have another garden. (There are examples of green on a sloped roof and not just flat or stepped roofs.) I could use water from my evaporative cooler to water the garden. But how much trouble will it be?

There are examples of public places such as overpasses that function as neighborhood gardens. There are even studies such as those at ASU in Tempe, Arizona that are studying the viability and effectiveness of green roofs in our climate. The most ambitious is the Tempe Transportation Center Roof. The Water Resources Research Center of the University of Arizona discussed that Center's roof and touts similar benefits to those mentioned above. By the way the Tempe Transportation Center has an LEED platinum rating.

Certainly green roofs have a place in the built environment. Retrofitting a house may be too expensive BUT designing new homes to have green roofs is a real possiblility.

This is a subject to be re-visited for sure.

COMING SOON: elpasopolitcally

Living Green in the Southwest: How to Stay Cool without Central Air Conditioning

From lifehacker.com

I returned last week to the Columban Mission Center to find out how they keep their building cool (an old home on Magoffin built in 1920) without central air conditioning.

I found inside to be comfortable - perhaps not as cold as it could be with central air, but pleasant and certainly more than meerly tolerable.

There are two large whole house fans in the attic above the second floor. At 4 AM, Father Bob Mosher opens all of the windows on the first floor and turns the fans on (this could be automated) and all of the hot air in the house is sucked out the attic vents and the cool air is sucked in. At daybreak he closes the windows on the east side of the house and at 8 AM he shuts all the other windows. He turns off the whole house fans. Ceiling fans are on throughout the day circulating the cool air. The lights throughout the building are left off except when needed. All the fixtures have fluorescent lighting.

The attic is well insulated and, in addition, two inches of styrofoam insulation was recently added to the outside walls of the building and stuccoed over. That too has helped to keep the indoors cooler during the hot summer. 

From elpasoinc.com. Proposed electric rate hikes.

Solar panels on the roof provide electricity during the day - something El Paso Electric Company wants to penalize all solar customers for having.

Click image to enlarge.

An eGauge app provides the Center with instant data about their energy usage including the electricity generated by the panels. The app provides real time data as well as data over a period of time.

Read a technology fact sheet to learn more about whole house fans including the difference in costs of running this fan versus central air. Try one penny per hour instead of twenty cents based on 8.5¢/kWh!


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Living Green in the Southwest: Paint Your Roofs White

[Sorry. If you receive these posts as an email, the videos will not embed. Please go to www.elpasonaturally.blogspot.com.)

In a previous post I said that painting your roof white is debatable. It reflects heat in the summer but how does it do with keeping the house warm in the winter? The people I know who have done it are happy in the summer and the winter. 

A Mother Jones article Cool It on the AC Already: How air conditioning is making us hotter supports using white reflective paint on your rooftop. Their point: "We spend $11 billion on cooling each year and release roughly 100 million tons of carbon dioxide in the process—the same as 19 million cars." The article gives the usual recommendations: turning up the thermostat, using fans . . . painting your roof white.

This first video should have been edited to cut to the chase: the difference between the temperature of an unpainted roof and a painted one. The difference is dramatic!

This next video is a how to and the how to is pretty simple. The example is that of a flat top roof but painting a pitched roof is the same. (BTW, it takes a lot of water to wash a roof so this may also be a good time to put in some gutters and use rain barrels to water your yard or garden.) 




Right now this strikes me as an early morning project or one that can best be done in the cooler late Fall. 

And btw, the Mother Jones article says that evaporative coolers are best in drier climates. Most of us in El Paso know that if we own an evaporative cooler. The concern is the amount of water that is lost when cooling this way. I use a bleeder hose that I can move and water different parts of my yard and garden. Just saying.