Designing Electricity Use for a Sustainable Home

by David Simms

Over the decade that my family and I spent living with a wind­mill to supply all of our electricity, we became acutely aware of exactly how much energy we used. Our appliances gobbled too much power, and many were the times we wished for the magical solutions in household technology that are now available off-the-shelf. In a sense, I now view our experience as a laboratory experiment, the findings of which could be applied to electricity use in the conventional, urban home.

I remember the sense of satis­faction I had when we managed to get our trusty Kenmore washer to run on 32 volts DC. I fixed it up so that a small inverter ran the controls and a wild half-horse electric motor did the real work. There was just one problem. The pulley ratios had to be fine-tuned because the tub turned so quickly that, when we went to retrieve the clothes, we had to gently peel an indistinct glob of multicoloured fibre from the edge of the tub. This glob of nearly dry thread had so vigorously attempted to extrude itself through the holes in the tub that individual items of clothing were nearly unrec­ognizable. I should have realized that I had also solved the problem of dry­ing clothes, not merely washing them. Had I not been young and inexperi­enced, I might have recognized some more potential in this craziness.

Today, we don’t need to pursue questionable experiments in dingy basements to create energy-efficient appliances. A lot of the heavy lifting has been done. All we need is to figure out how to make the payments when buying this new technology because, in our globalized world, it’s all avail­able, somewhere. With global warm­ing well under way, the potential to drastically cut our electricity use could not come at a better time.

Why?

According to Environment Cana­da, electricity generation using fossil fuels is Canada’s number two source of greenhouse gas emissions (GHG). At 129,000 megatonnes (Mt), electric­ity generation follows transportation, which has grabbed the gold medal at 200,000 Mt. In terms of individual fa­cilities, the top five spots on the GHG list of big emitters have been awarded to coal-fired power plants. While gov­ernments dither, the buck has to stop with the consumer. Why wait for ini­tiatives that may never appear?

Individually, we are capable of reducing our electricity use to about 20% (yes, that is a reduction of 80%!) of what is considered to be “conven­tional.” There’s no doubt that it would cost money to do this. Yet, when the analysis is done, our investment will show itself to be surprisingly cost ef­fective. Investing in efficient technol­ogy today is also a hedge against fu­ture hikes in the cost of energy.

In 1997, the Danish island of Samso embarked on an aggressive program to get completely off fos­sil fuels. Most of the cash needed to build the windmills and set up the district heating systems came from local investors, but the guiding eco­nomic rationale is that Samso consid­ers it a much better deal to pay inter­est, in today’s currency and at today’s costs, than to face higher oil costs in the future. The same reasoning could be applied to our individual or family situations.

No Hardship

In Table 1 below, I have designed a probable consumption profile for a reasonably average household. Gone is the old energy-hogging beer fridge. Gone is the electrically heated hot tub and gone is the half-horse circulation pump that runs 24/7 to filter water in the backyard Olympic-sized swim­ming pool. Gone also are the parasitic little digital clocks and power sup­plies. The monthly total adds up to 552 kilowatt hours (kWh).

Note the big energy consumers: lighting, refrigeration, hot water, and clothes drying.

A quick comparison with Table 2 shows what can be done with a mini­mal impact on lifestyle. The last column of this table also gives the ap­proximate marginal, over-and-above, cost of these technologies when com­pared to conventional appliances. Here are the options.

Lighting

Lighting efficiency demands that incandescent bulbs be replaced with compact fluorescents. Studies show this to be a zero-cost solution. Despite the higher purchase price, CFLs pay for themselves through a longer life and through energy savings.

Cooking

There’s not much to do about cooking except to pay a bit more at­tention: use pans that fit the burners, use appropriate heat settings, use the microwave, crock pot, and pressure cooker more, and try to eat more raw vegetables. Resist the temptation to pull stuff out of the freezer and de­frost it in the microwave. Give it time to defrost at room temperature and save energy. Cooking larger amounts, for several meals at one time, is also an effective strategy.

Hot Water

Providing hot water is perhaps the most challenging exercise in re­ducing household energy consump­tion. It’s quite facile to simply allow the word “solar” to roll off our lips. But to even pretend to heat water dur­ing the cloudy weather of winter, so­lar hot water systems must be vastly oversized compared to what is needed to do the same job throughout the warmer months. So we could use a passive, batch-type water heater for spring, summer, and fall. It’s just a black tank in an insulated box. It uses no pump, electronics, or antifreeze. It is very resistant to transient, zero-de­gree temperatures and to overheating. Some people build their own batch heaters, they’re that simple. You can find plans at www.builditsolar.com.

A solar batch water heater would need to be backed up for winter use. For this, use point-of-use, demand wa­ter heaters that can save nearly 50% of hot water energy. These units are so cost-effective that I see no barrier to installing more than one of them. Install one, right at the bathroom and another for the laundry/kitchen. Over­all, this recipe should save nearly 75% of the hot water demand. Low-flow shower heads and short-haired people will also help to make this solution feasible.

Refrigeration

We can save over 2 kilowatt hours a day for both the fridge and freezer by replacing them with state-of-the-art units. Sun Frost is a small California company that developed a line of fridges especially for off-grid, solar use. Fortunately, these refrigera­tors can also be used on utility power. These units demonstrate what huge differences in energy consumption a few common-sense design changes, like really thick insulation, can ac­complish. Sun Frosts are made in up­right configurations that can fit into a regular kitchen. Sun Danzer is another company that sells a horizontal freez­er-like unit, built in Romania with a compressor from Denmark. These amazingly efficient units can be set up as either a fridge or a freezer by installing the appropriate thermostat.

Clothes

Over the last few years, the appli­ance industry has started to move to­ward front-loading washing machines. They use less energy, water, and soap but they employ one fantastic feature that can result in even greater energy savings: spin speed. When it comes to drying clothes, it helps if most of the water has already been removed. This is what high spin rates do.

We’ve compared a couple of these front loaders. An older Swedish Asko we once owned could spin at 1,500 rpm, whereas our present Whirlpool peaks out at 900 or 1000 rpm. Since the water-extracting centripetal force varies with the square of the rotational speed, 1,500 rpm will be over twice as effective as 1,000 rpm. The Asko uses dynamic balancers to keep the wash­ers from flying off into Earth orbit, while the Whirlpool uses an internal block of concrete to keep it anchored to terra firma. Once we get the equiv­alent of the washing machine pilot’s licence and learn how to run these things, they can also double as home entertainment centres. Never mind the X-box – an Asko is much more fun!

Drop the dryer! Your grandmoth­er never used one. Although clothes drying can be a challenge during the winter, your high-tech washer should help you to do an end-run around a se­verely entrenched energy hog.
 

The Economics

While few people bother calcu­lating payback terms on a favourite set of golf clubs or their brand new Bimmer, some people seem to think that saving energy must be justified in economic terms.

Table 3 shows what the payback period on all of our changes would be. From table 2, we get an estimate of the cost differential – what the conserver technology would cost over and above conventional technology – which is $5,500 for the package described. Ta­ble 3 gives us the simple payback pe­riod, based on local power rates. So, if we pay $.08 per kilowatt hour (we must also include any electricity de­livery charges), our energy savings of 427 kWh (552 minus 125) would have a value of $34.16 per month. At this rate, the so-called “debt” of $5,500 would get repaid in 13.4 years. After that, we get to enjoy the benefits of conservation at no cost. Since today’s investment can be tomorrow’s hedge against inflation, the payback time is a conservative estimate.

Table 4 shows what the costs of mortgaging the technology would be. For this table, I assumed a 20-year mortgage, at various interest rates. If we were “mortgaging” the $5,500 outlay at 6% interest, we’d need to pay $39.18 per month. To see how close our energy savings would come to paying this, we go back to Table 3 to see what dollar value our savings would have at current rates. To cover the mortgage payment, we’d need power rates a bit over $.09 per kilowatt hour.

The moral of this lesson is that conservation is very close to being cost-competitive with cheap elec­tricity. Compared to more expensive electrictiy, conservation is the hands-down winner. Conservation doesn’t require more coal generation, more nukes, or more land to be flooded. If generally implemented, a conserva­tion “path” might even permit some facilities to be mothballed. A corol­lary to the economic competitiveness of conservation is that we’d also see considerable economic activity and job creation.

Next time you’re talking to your favourite politician, if you still have one, tell him or her about this. A con­server scenario is a win-win proposi­tion; the environment wins and the economy wins.

***

David Simms is a retired teacher with a lifelong interest in energy mat­ters.

[From WS January/February 2008]

Related Posts

Watershed Sentinel Original Content

5 Issues/yr — $25 print; $15 digital