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Saving Water — Saving Energy

Saving energy isn’t only about using less electricity and fuel; it’s also about saving water

Posted on Apr 10 2014 by Alex Wilson

In this weekly blog, I’ve focused a lot of attention on the energy-saving measures at our new home — from the innovative insulation materials we used to the air-source heat pumpHeat pump that relies on outside air as the heat source and heat sink; not as effective in cold climates as ground-source heat pumps. heating system and our top-efficiency heat-recovery ventilator(HRV). Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger; a similar device, an energy-recovery ventilator, also transfers water vapor. HRVs recover 50% to 80% of the heat in exhausted air. In hot climates, the function is reversed so that the cooler inside air reduces the temperature of the incoming hot air. .

What I haven’t said much about are the measures we’ve taken to reduce water use and why these measures save energy as well.

The water-energy nexus

Before getting into specifics, it’s important to note that there is a close relationship between water and energy — even when we’re not talking about hot water. At the macro scale, it takes at lot of water to produce energy.

With electricity generation, each kilowatt-hour (kWh) of electricity generated (based on national averages) consumes 2.0 gallons of water, according to a 2003 paper by National Renewable Energy Laboratory researchers (PDF download). This is mostly from evaporation of water at thermoelectric power plants, but also includes evaporation of water at reservoirs used for hydropower generation.

Other energy sources consume a lot of water in production. We can refer to this as the “embodied water” of these energy sources. Simply pumping oil out of the ground isn’t all that water-intensive, but when we start getting into “enhanced recovery” technologies like hydraulic fracturing (fraking) the water intensity goes way up — and can be a limiting factor. It may increasingly lead to conflicts with farmers in arid regions that are rich in underground oil and natural gas.

At the same time, treating and distributing water and treating wastewater use a lot of energy. This is especially the case with municipal water and sewer systems, but even in rural areas with their own water systems, water pumping can be one of the largest energy consumers — to operate deep-well 220-volt submersible pumps.

Water conservation

It is in this context that I consider water conservation to be an extremely important priority. We are fortunate in Vermont to have plenty of water, but I’m just back from California, which is dealing with one of the most severe droughts in decades. Flying over the Sierras on my way there I was shocked to see how little snow cover there was.

So what are the water conservation measures we implemented at our new house?

Low-flow showerheads

We installed EPA WaterSense-certified showerheads that deliver 1.75 gallons per minute (gpmGallons per minute. Measure of liquid (usually water) flow.), vs. the federal standard 2.5 gpm for showerheads. Ours are Kohler Bancroft showerheads, and we are very pleased with them, though I’ve also used a Delta H2Okinetic showerhead using just 1.5 gpm and been very happy with that, and I recently used a Niagara Conservation showerhead rated at just 1.0 gpm and found that to work just fine.

When we save water with a showerhead or faucet, we also typically save energy use directly, since we’re using less hot water. Indeed, in replacing older, high-flow showerheads with new low-flow models, the payback for that change is often measured in months or even weeks, instead of years.

Low-flow faucets

The Kohler faucets in our two bathrooms are WaterSense-certified at 1.5 gpm, vs. the maximum 2.2 gpm.

Interestingly, almost the entire plumbing industry has shifted to 1.5 gpm flow rates — the level required for WaterSense certification. Because we rarely turn on the faucet full-force, our actual consumption is a lot lower. Screw-in faucet aerators are inexpensive and can quickly convert most standard faucets to water-saving versions.

Low-flush toilets

We have two bathrooms: upstairs and downstairs. Both have Kohler high-efficiency toilets that use just 1.28 gallons per flush (gpf).

I admit to having been somewhat skeptical that 1.28 gpf would be enough for satisfactory performance, but in the three months we’ve been in the house we’ve had zero problems. The toilets are performing beautifully.

Water-efficient clothes washer

I remember when I bought my first new clothes washer 25 or 30 years ago, I had to work pretty hard to find a water-conserving horizontal-axis (front-loading) model. At the time there was only one U.S. manufacturer producing such a product for home use (White-Westinghouse).

Fortunately, it is a very different situation today, with nearly every manufacturer offering such products. We bought a Whirlpool Duet washer, which I think is the best of the U.S.-made models. We had one in our last home and were very pleased with it. The only difference with this purchase is that the washer (and matching dryer) are larger, since Whirlpool shifted manufacturing to the U.S. from Mexico, and the units grew in size.

Because we typically wash clothes in cold water, our direct energy use for clothes washing is very low.

Water-efficient dishwasher

We bought a mid-range KitchenAid dishwasher and are very pleased with it so far. We operate it with the no-heat-dry feature selected on a normal or light cycle to further reduce water and energy use. Roughly 90% of the energy use by dishwashers is for heating the water, so a water-conserving dishwasher also saves a lot of energy. With the Normal cycle and assuming typical soiling of dishes, a load of dishes uses just 2.9 gallons — far less than was the case a decade ago.

It’s worth noting that using a modern, EnergyStar-rated dishwasher typically consumes a lot less water than washing dishes by hand.

Knee-control kitchen faucet

We brought down from the house we moved out of a great kitchen faucet control system made by TapMaster that lets you turn the faucet on an off by either pressing your knee into one of the under-sink cabinet doors or by pressing a toe plate with your foot. This way you can easily turn the water on and off while you’re washing a pot or rinsing dishes.

There’s no reason to leave the water running, so moderate water savings can be achieved. It’s also a huge convenience!

Water is precious

In the years and decades ahead, water may well be a bigger challenge than energy in many areas of the U.S. and world. We should all do our part by using this precious resource efficiently.

Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. In 2012 he founded the Resilient Design Institute. To keep up with Alex’s latest articles and musings, you can sign up for his Twitter feed.


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  1. Alex Wilson
1.
Thu, 04/10/2014 - 21:15

Alex, your emotional plea
by aj builder, Upstate NY Zone 6a

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Alex, your emotional plea verses logic. Where water exists in huge excess, the last thing one needs to do is use less in some way to do "our part."

IMPOSSIBLE.

Any water not used here where you and I have too much is not able to be used by California.

NO logic, you lost me. Stick to logic and I will back you up. next time.

Saving water fees and energy... does make sense, I agree and practice such.


2.
Thu, 04/10/2014 - 23:40

3L Toilet
by Sean Botham

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There is also an ultra low flow toilet from Niagara Conservation that works amazingly well. I have this 3L/ 0.8gpf installed in my own house and rental units (different supplier in Canada, but same toilet). It doesn't look special, but it has a 800g MaP rating and I've had no issues with it. Best performing toilet I've come across! Just not recommended for commercial applications where there are long lines.


3.
Thu, 04/10/2014 - 23:40

h2okinetic is great
by Eric Sandeen

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That's still my favorite low-flow shower head.

I've also had good luck with the dual-flush retrofit kits for toilets, FWIW.

Thanks for the heads up on that tapmaster control - very cool!


4.
Fri, 04/18/2014 - 20:20

low flow showers
by Jon R

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I can confirm that with high water pressure, one can take an enjoyable shower at less than 1 GPM. That's an easy and significant energy saver.


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