Perhaps the greatest challenge to promoting energy efficiency is that you can’t see it. People understand electricity produced from a PV collector on the roof, and a kWh meter can easily report precisely how much energy was generated. But with more-efficient products, savings cannot be directly measured; instead, one must reckon the difference between a real and a hypothetical situation. This complexity creates a lingering uncertainty whether the promised savings did or did not actually occur.

There’s another paradox related to the evaluation of energy savings. Conscientious program managers and energy professionals should want to collect energy consumption data and perform the necessary analysis to be sure that the technology worked as expected. After all, how can one learn from mistakes if the mistakes aren’t observed? But the world works differently. If the preliminary estimates are proven correct, then program managers are open to criticism for wasting money on needless and expensive evaluations.

Alternatively, if the savings are less than expected, the managers are criticized for running ineffective programs or installing defective technologies. In an era of declining funding and short time horizons, they can’t win. I can understand why they would want to skip the measurements and I can sympathize with them.

That's why two articles in Home Energy's current issue quantifying energy and water savings from high-efficiency equipment are especially welcome. One article describes the energy and water savings to be gained from replacing old clothes washers with more-efficient units (see "Do Savings Come Out in the Wash?"). The savings are large: The most efficient units cut water and energy use almost 50% compared to the original units. And this study took place in mild San Diego; the savings could be greater in colder climates. The results also demonstrate the need to study the clothes washer, water heater, and clothes dryer in combination. The energy consumption of these three appliances is inextricably connected, depending as it does on hot- and cold-water consumption, internal water heating, and spin speed.

This study had another intriguing result: With increasingly efficient clothes washers, the energy conservation battlefields are shifting. The dryer is now the largest electricity consumer in many homes, thanks to shrinking consumption by refrigerators and lights. It’s time to develop and commercialize technologies that increase the efficiency of clothes dryers. Heat pump dryers are now crossing the Atlantic, but other technologies, such as heat recovery, deserve attention. A zero energy technology crossing both the Atlantic and the Pacific is line drying. It’s done overseas because energy is expensive, and some simple devices make it more convenient. A second battlefield may be the rising cost of detergents. Is Proctor and Gamble capturing an unfair share of the energy savings? This will be the topic of a future article.

The article on water savings found that replacement of relatively new toilets with better-designed, water-efficient units cut water use by greater than one third (see "Does Replacing Toilet Fixtures Save Water?"). Service calls fell dramatically, too. These outcomes demonstrate that the evaluator’s paradox has a third outcome, that is, the savings are larger than expected and include benefits not initially considered. A solid example was provided in this article with evidence that was obtained through only modest data collection and evaluation. Where skeptics question the difference between hypothetical and actual savings, these two articles prove that not only can efficiency gains be measured, but that the outcomes are real and substantial.

- Alan Meier

Views: 115

Comment

You need to be a member of Home Energy Pros to add comments!

Join Home Energy Pros

Home Energy Pros

Home Energy Pros was founded by the developers of Home Energy Saver Pro (sponsored by the U.S. Department of Energy,) and brought to you in partnership with Home Energy magazine.  Home Energy Pros is sponsored by the Better Buildings Residential Network.

Latest Activity

Evan Mills replied to Sandra K. Adomatis, SRA's discussion Green Mortgage Appraisal Roundtable
"Would love see your slides, but the AI site requires login.  Can you post them here or email…"
2 hours ago
Colin Genge posted a blog post

What needs to be done to get builders to follow Code for duct and envelope leakage?

“Have you been ripped off for $100,000 by your builder?  Let us help you get what you paid for! …See More
8 hours ago
Green Training USA posted an event
Thumbnail

Proctor’s Without Borders at Online

July 29, 2015 to August 7, 2015
Complete your training at your own pace and take exams when you want and where you want. No…See More
17 hours ago
Gar Swaffar commented on Gar Swaffar's blog post Cost of using a BPI QCI?
"Ip.s., I would presume there will be a difference between the Left Coast and nearly everywhere else."
yesterday
Gar Swaffar posted a blog post

Cost of using a BPI QCI?

I'd like to find out if there is a consensus on a rule of thumb cost of a QCI onsite for…See More
yesterday
Gar Swaffar is now a member of Home Energy Pros
yesterday
Colin Genge posted an event

Infiltration and Duct Leakage with BPI at Online

July 30, 2015 from 1pm to 2pm
Blower door and duct test requirementsCalculating resultsCertification optionsTest preparation and…See More
yesterday
Stacy Hunt posted an event

Volunteers needed for the upcoming U.S. Department of Energy Solar Decathlon in Irvine, CA at Orange County Great Park

October 8, 2015 at 11am to October 18, 2015 at 7pm
Volunteer for the upcoming U.S. Department of Energy Solar Decathlon 2015, taking place Oct. 8-18…See More
yesterday

© 2015   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service