GreenBuild Blog

Thursday, August 19, 2010

Ten Steps to Prevent the Next Urban Water Crisis - Part 1

Some of these five actions are immediately possible; others are long-term fixes that will depend on the water issues in a specific region, as well as local political and economic factors.

1. Design, construct and operate non-residential buildings to reduce water use, including reducing energy use (in large buildings, this also reduces water use in cooling towers).

2. Reduce household water use, starting with water audits, installing efficient technologies and changing behavior. Do the easy stuff first: shower heads, faucets and toilets. Then look at dishwashers and laundry water use. Finally, look at reusing graywater and rainwater for irrigation. Home water audits include an analysis of personal behavior as well as the efficiency of fixtures and appliances in the home.

3. Recycle, capture and reuse water more than once; this is the basic principle behind graywater, rainwater and blackwater recycling technology and practice. The key is to match water quality from the supply with required water quality at the point of demand.

4. Reduce water use in landscaping both homes and buildings, with effective irrigation technology and revised plant choices, emphasizing native and adapted vegetation. For more information on home landscaping water conservation, contact any local Extension Service, typically associated in each state with a land-grant (public) university.

5. Water pricing should be structured so that rates rise steeply with use, resulting in significant economic penalties for water waste and excessive water use. Bringing the marketplace into the picture and avoids having to institute severe restrictions on individual choice and employ “water cops” during drought emergencies.

Systematically applied these five steps begin to move us away from the cliff of future water shortages. Next post, I’ll add the final five steps.

At the €2 million DEUS 21 research project in Knittlingen near Pforzheim, Germany, the Water House not only cleans rainwater and recycles wastewater from the connected households, but it also produces biogas and electrical power. Courtesy of Klaus König.

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Wednesday, August 11, 2010

Graywater Systems Provide New Water Resources

This graywater system provides good-water-quality effluent without chemicals, using filters, biological treatment and UV-sterilization.
Courtesy of Pontos/Hansgrohe AG.

graywater toilet mechanism

This integrated sink/toilet fixture attempts to recycle graywater from hand washing and other sink use directly into the toilet tank. Courtesy of Caroma.

On a visit to Frankfurt, Germany, as part of my research for Dry Run: Preventing the Next Urban Water Crisis, I saw a packaged graywater system in use at a large office complex. The AquaCycle, manufactured by the Pontos division of German manufacturer Hansgrohe, relies on biological, rather than chemical treatment. After pre-filtration, the graywater is treated with oxygen at normal atmospheric pressure. Microorganisms inside a treatment tank break down the biodegradable content of the water with metabolic processes. Surplus biologically active sludge is automatically removed and fed into a wastewater drain. The water undergoes the same treatment a second time and then passes through a UV (lamp) light for sterilization. After this treatment stage, the recycled water is odorless and can be stored for long periods of time.

Packaged graywater systems for commercial projects are also available from other manufacturers such as Brac Systems. For household systems, you’ll have to turn to local companies that can assemble the project from components or perhaps find a pre-engineered system, such as the Aqua2Use system from Australia, imported by WaterWise Group.

Perhaps the simplest graywater harvesting system for residential applications is the integrated sink/toilet combination. This new fixture, available from both Caroma and Sloan Valve, takes water from washing, shaving and other sink uses and puts it directly into the toilet tank as graywater for future flushing. As we enter a new era of water conservation thinking, more companies are going to produce similar systems, so that no usable water ever goes to waste!

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Water Conservation Begins at Home - Think Twice, Flush Once!

In most homes, toilets are the largest water user inside the home. Although the federal Energy Policy Act of 1992 mandated a maximum of 1.6 gallons per flush (gpf) for new toilets beginning in 1994, many homes and apartments still have older toilets that might use 3.5-gpf or more. If you’re in an older home, get rid of that old flusher fast!

High efficiency toilets (HETs) use at least 20 percent less water than standard 1.6-gpf models. The most popular household HET is the dual-flush toilet. Dual-flush toilets use about 1.6-gpf for solids and 0.8 to 1.1-gpf for liquids. For a household of four people, the savings from a dual-flush toilet is about 3,360 gallons annually, reducing water use for sanitation by 37.5 percent and total household water consumption by 10 percent.

Nearly every toilet component, including the tank, flush valve, bowl rim and trapway, has been re-engineered using tools such as Computational Fluid Dynamics (CFD) computer modeling, making today’s models far more reliable than first generation HETs from the 1990s.

In the 1970s, during times of water shortages, a popular motto was, “If it’s yellow, let it mellow; if it’s brown, flush it down,” and everyone put bricks in their toilets to save water. Now, with dual-flush toilets, we can accomplish the same goal and not disrupt the flushing mechanism.

Dual-flush toilets potentially can save 25 percent or more of the water used in current flush-toilets and much more compared with older (pre-1992) models. Courtesy of Caroma.

Water Efficiency • Green Building News • Permalink

Monday, August 09, 2010

Time to Put Rainwater Harvesting into Every Green Building Project?

Capturing the free water falling from the sky is gaining popularity in the U.S. and in other countries as diverse as Australia and Germany. When considering rainwater harvesting, we usually think of the “active” variety. Active rainwater harvesting combines collection and storage with on-demand use and is an excellent way to supplement residential and commercial water supplies, because rainwater is soft and free of disinfectants, salts, minerals and human contaminants. The majority of rainwater captured in this manner is used for irrigation and flushing toilets. With today’s water prices, rainwater collection and reuse systems typically have medium-to long-term payoffs. However, there may be other financial benefits for commercial projects such as reduced sewage collection costs and lower water meter fees (because a project might need less municipal water.) “Passive” rainwater harvesting, on the other hand, is less expensive. This form of rainwater harvesting typically falls into the realm of landscape design/construction professionals and involves studying the land and its natural water flows, with the goal of directing runoff to plant basins or areas where it can be infiltrated directly into the soil or via a pervious pavement or other surface. We’re going to see a lot more of both varieties of rainwater harvesting in the next decade, as urban water crises occur more frequently, requiring project designers to come up with new water-conserving approaches for building projects. Read more in Chapter 9 of my new book, Dry Run, available on this site for free download.

Water Efficiency • Green Building News • Permalink

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