Tuesday, July 18, 2006

Water Efficiency

source: http://sustainabledesignupdate.com/?p=30

Arenal Waterfall

We (I mean Archiopolis Architects when I write we) feel water conservation and our care for the environment is reflected in how we design with water. We believe that water should flow, gurgle and percolate into the ground on our projects in about the same manner it did before we started work. This means we pay careful attention to surface drainage, runoff, soil types and prevailing winds. Sometimes a site will recommend that we design specific water features while other times we help water flow into the aquifer.

Inhabitat has a continuing series on Sustainable Design, recently they covered Water Efficiency.


There are few things we take for granted as much as our ability to turn on the tap and get water in seemingless endless supply. Even during droughts, and in spite of ubiquitous advertising about shortages and conservation, most of us treat this precious resource as a given.

The average American uses 80-100 gallons of water per day; and while less than half of it will be drunk or used to cook food, chances are that all of it is treated, potable water from the municipal water provider. What many people don‚'t realize is that it's fairly easy to implement simple systems for recycling and reusing water on your own property, drastically decreasing the demands on shared supplies, and in turn, reducing your water bills.

Read on for details on the three LEED-H criteria for water efficiency at home, plus some additional information on innovations in wastewater treatment and reuse.

Green Building 101, water efficiency, efficiency, water, rainwater catchment, collection, cistern
Glen Murcutt's South Wales house collects and funnels water through the roof's central groove.

1) Water Collection and Reuse: If you hate to miss out on a great bargain, look out the window next time it storms to see what you're passing up there's no more cost effective water source than rain. In fact, if one rainstorm drops 1 inch of rain on your yard, you have just watched the equivalent of over 250 bathtubs full of water trickle by!

The first step for increasing water efficiency at home is to reduce the use of drinkable water for non-consumption purposes. There are two ways to do this: collect rainwater and reuse indoor wash water. You can install cisterns above or below ground that will collect and store run-off from rooftops and other impervious surfaces; as well as from laundry machines, dishwashers, bathtubs and sinks (this is classified as grey water, meaning that it does not include human waste or sewage).

These collection tanks can then serve as an on-site supply for watering your lawn and garden. It's also possible to reuse grey water indoors in toilets and for washing, but the regulations and requirements are a bit more complex than for outdoor use. Regardless, there are varying degrees of treatment and filtration that can be installed in conjunction with your cistern, depending on what you intend to use the water for.

Green Building 101, water efficiency, rainwater, cistern, collection, water, efficiency, catchment, reuse
Stay tuned for more on this gem of a site-sensitive house in the next week.

2) Irrigation: How many times have you driven past someone's house during a midsummer downpour and seen their sprinkler system going full blast in spite of the free water falling from the sky? The irrigation of lawns and gardens consumes up to 50% of the potable water we bring onto our property.

This is an instance where technology can be hugely beneficial in conserving natural resources. You can install smart, programmable sprinkler systems and moisture sensors that allow you to measure the amount of water your yard needs at any given time, and control irrigation from a central shut-off valve. Combine this system with your rain and waste water collection and you've got your outdoor greenery dialed.

As was pointed out in last week's Green Building 101 installment on Sustainable Sites, its wise to choose landscaping elements that are appropriate to the climate and require minimal water. Because of their varying root systems, grass, trees, and flowers all have different water requirements. When you design your garden, consider the layout of the irrigation system, and try to arrange plants according to the amount of water they need.

Green Building 101, water efficiency, landscape, garden, water, irrigation, reuse, grey water
Researching water-wise plants for your particular region makes a lower-maintenance, lower-cost garden.

3) Indoor Water Use: The primary means of reducing indoor water use has to do with the fixtures you choose. Selecting low-flow sink and bathtub faucets, showerheads and toilets can reduce indoor water use by 30-40%. Over the last few years, the quality of low-flow fixtures has increased. Whereas at first they gained a reputation for flushing inefficiently or delivering unsatisfactory water pressure, new products are surpassing the original designs. The other great way to ensure that you are getting maximum water efficiency indoors is to purchase Energy Star appliances, which guarantee a certain degree of water efficiency, and save energy to boot.

water, efficiency, Green Building 101, home, bath, environment
The Kohler Watertile is designed to be water efficient (if you don't install 6 of them in one shower!)

Water Treatment Using Nature Tools
Because water is so vital, and because the ability to clean and reuse it becomes increasingly important, it's an area where we've seen significant evolution and real innovation over the years. Early building strategies recognized the value on a single slant roof, which allows run-off to be collected in one place. Likewise, gravity obviously supports water pressure, so the higher above ground a storage tank sits, the more efficiently the water will feed out.

Green Building 101, water efficiency, Living Machine, Eco Machine, John Todd, water, wastewater treatment, bioremediation, efficiency

Then there is the natural water-filtering ability of plants a form of bioremediation which a number of ecologists, scientists and engineers have learned to harness for large scale filtration of contaminated water. Ecologist John Todd's Living Machines (now known as Eco Machines) create consolidated ecosystems which treat wastewater and sewage using aquatic plants, fungi, and other organisms. These have generally been used in commercial-scale operations, and not scaled down for residential purposes, or up for city-wide water treatment. But the concept reminds us that our own greenspace can be a filter for the water we waste, making reuse easier.

If you're a regular reader, you know we take every opportunity to promote green roofs which are a great way to utilize rain water and divert it from running off-site. Other rain catchment systems can be devised in the form of botanical facades, and modular permeable pavement. Whatever you can do to make use of rain and wastewater means you spare your city sewers from an overflow of contaminated water, and you end up with a more fertile, verdant garden.

water, home, green building 101, floating, efficiency
You canĂ¢€™t get much more aware of the water than in a floating home, like this one from the Dutch Waterstudio.

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