Water Efficiency Often Ignored in Green Buildings

With all the attention on energy efficiency in buildings and where all that energy comes from (renewable sources or coal-fired electric plants), there is one resource that seems to be ignored - water.  And the really scary part is that although we can generate more energy from various sources, the water that is on the planet and in the atmosphere is all we have to work with - and we know it.

You may be thinking that there is plenty of water around, but when you get down to the science of the amount that is readily available for human consumption, the picture changes.

• » See also: Harvesting Rainwater From an Arid Future
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As Rob Watson says in his article, “Water, Water Everywhere,” posted on GreenerBuilding News:

To refresh peoples’ memories about water distribution: About 97 percent is salt water and 3 percent is fresh. Two of the 3 percent is locked up as ice in the poles. Of the remaining percent, roughly two-thirds is underground and one-third is surface water. Of the underground water, about half is too deep or saline to use effectively and another quarter is polluted. About half of the surface fresh water is too polluted to treat for use. The non-polluted part of underground and surface water is what’s left for us. For those following the math, about four- to five-tenths of a percent of the planet’s water is reasonably available for ALL human use.

In his article, Watson advocates a market approach for conserving and using water efficiently.  As he reminds us, the current system is a little backward: Water falls to the ground in a distributed fashion (in other words, not all in one spot), then our treatment systems take the water to a central location to be cleaned, and then it is distributed again.

So, what can we do to reduce waste of the little bit of fresh water we have?  Ironically, Watson says part of the answer lies in energy efficiency.  One of the largest uses of fresh water is energy generation.  The use of water in coal mining and power plant cooling towers represents the largest uses of fresh water.  “A 30 percent reduction in energy consumption could result in water savings almost equivalent to the annual use of the ENTIRE public water system consumption in the country (i.e. buildings)!”

We’ve come full circle it appears.  Yes, there are other ways to save on water use (low flow fixtures, drought tolerant landscaping, rainwater harvesting, etc.), but the biggest bang for the buck comes from reducing energy use.  With only four- to five-tenths of a percent of the earth’s water ready for our use, we’d better get crackin’.

Photo furnished by David Masters, through a Creative Commons License.

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