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Water Conservation: Hidden Benefit of Energy Efficiency

Some time ago, we in the green building world realized that while energy efficiency is a critically important aspect of sustainability, water conservation merits equal attention. Without energy, we might get cold and be inconvenienced. Without water, we die in a matter of hours or days.

IndoorWaterUseIn the US, water has been seen as universal, ubiquitous – an infinitely available, low cost commodity. Yet the politics of water supply define the development of the western US. You need only look at the sad reality of the Colorado River, the energy intensity of the California Aqueduct system or the ecosystem politics of the Columbia River Basin to see that the storage and distribution of water is far from low cost or infinitely available. Read or watch “The Cadillac Desert” for a quick, if slightly dated, education.

The consumer’s perception that water is inexpensive, however, has led to a lack of interest in water conservation, particularly when compared to the current focus on energy conservation. News Flash! – while we’ve been staring at our insulation levels and measuring our building air changes, things have changed in the world of water – market forces are at work.

1598_Alley_2015C_01I’d like to use the work we’re doing with Quadrant Homes as an illustrative example. In 2008, we started working with Quadrant Homes and the Northwest Energy Star program to develop an energy upgrade path for Quadrant’s homebuyers to meet the Federal Energy Efficiency Tax Credit. This meant a 50% reduction in space conditioning energy below the IECC 2005 model code; perhaps a 25% improvement over our Washington Energy Code (WSEC)of 2006. Over time, they have continued to evolve their designs, equipment efficiencies, and construction quality to keep their energy performance substantially ahead of our local codes, which already set a high bar.

While this attention to detail has led to comfort and durability benefits for their customers, the already high code threshold, our moderate climate and the low cost of energy in the region, means that the achieved energy conservation of a Quadrant Home, compared to a WSEC 2009 code home, converts to roughly $250 in savings to the homeowner each year .

FaucetIn compliance with the new Energy Star requirements, Quadrant is installing water conserving fixtures in kitchen (1.5 gpm) and bathroom (1.0 gpm) faucets, and shower heads (1.75 gpm). The intent of this, from the Energy Star perspective, is to reduce the demand for domestic hot water – that’s where a good chunk of the energy savings come from.

What has surprised us is the economic benefit to the homeowner of the water conservation measures. Using standardized consumption calculations and code-required fixtures to calculate a baseline for comparison, we’re seeing a savings of roughly 19,000 gallons (25.6 hundred cubic feet – CCF) of potable water per year. In a typical example suburban neighborhood with water metering, homeowners are paying $4.97/CCF for water and $5.31/CCF for sewer – that’s a savings of $263 per year – equivalent to the energy savings from the Energy Star certification. So a new Quadrant home saves you about $50/month in combined energy and water savings. That’s significant!

If you were to add a 1.1 gallon average flush toilet and Energy Star clothes washer and dishwasher (which both use less water than standard models) the savings increase to 27,200 gallons or 36.4 CCF, bringing another $10 per month in savings.

Green building is best seen a whole systems approach – by focusing on all the resources consumed in a building, developers, owners, and our society in general can realize fortuitous but often hidden synergies such those illustrated in the Quadrant example.

Alistair Jackson, CSBA is a Principal at O’Brien & Company. He was involved in the development of the original LEED for Homes Pilot Rating System and is, among other things, the Quality Assurance Designee (QAD) for O’Brien & Company’s role as LEED for Homes Provider. He is a strong advocate for market-led innovation and market transformation towards sustainability. He is also a father of two – and impatient for change towards a better future.

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