What's the payback requirement for an energy project?

Sept. 5, 2008
Editor in Chief Paul Studebaker, CMRP, asks, "What’s your payback requirement for an energy project?"

In June, I used this space to ask how you would recommend I spend my economic stimulus check to best benefit the U.S. economy (“Stimulation Conundrum”). One of my favorite responses came from Mark Hose, a technician in Reedville, Va., who said he planned to invest in renewable energy for his home. I’m not ready to install solar cells, but as a first step toward higher efficiency, I decided to baseline our house with a professional energy audit. (Find certified auditors at www.resnet.us — our audit cost $500.)

It turns out the audit is the easy step.

For background, ours is a simple house built in 1975 to the minimum standards the codes allowed. It’s a 26 ft. by 32 ft. two-story box on a finished walk-out basement, with a gable roof on trusses and lots of vinyl-clad Thermopane double-hung windows. When we moved in (1987), I boosted the attic insulation to R-30. In 1997, we had the gas forced air furnace, central air and tank-type water heater replaced with the most efficient equipment we could find. We also had the HVAC zoned by floor in an effort to deal with stratification that tends to keep the upper level too warm and the lower level too cold. In 2006, new siding was preceded by housewrap to reduce infiltration.

I thought the house was pretty efficient, but when I plugged its size, number of occupants, location and energy consumption into the Energy Star program’s Home Energy Yardstick (search www.energystar.gov using “yardstick”), we got a score of 2.9 out of 10 — only 29% of comparable homes use more energy, according to the Energy Star database. I was miffed, and accused my family of leaving lights and electronics burning, overriding the thermostat programs and taking long, hot showers behind my back. Of course, they denied everything (except the showers).

The auditors arrived on a hot day in July, shut down the A/C and water heater, installed a blower door and used plastic wrap to seal the flues and all the ductwork inlets and outlets. Then they adjusted the blower speed to put the house at a negative pressure of 0.2 in. WC, measured the infiltration rate and walked every room using experience, their hands and occasionally an infrared camera to locate places where warm air was entering. Measuring again with the ducts uncovered gave the rate of duct leakage from outdoors.

They also took note of insulation amounts and locations, details of construction, appliance ratings, types of lighting and annual energy consumption.

The auditors’ findings give the house a home energy rating (HERS) of 82, solidly in the second-from-best “5 Stars” category. But with a little work, they say, the rating could be raised to 77, still lower than the best “5 Stars Plus” category but better, nonetheless. (For more about HERS, search www.energystar.gov using “HERS.”)

That work includes six improvements ranging from caulking and sealing gaps at the upper-level ceiling penetrations (estimated cost $100, estimated annual savings $91) to drilling holes in the first-floor ceilings and foam-filling the second-story floor framing at a slight cantilever over the front elevation brick half-wall (cost $400, annual savings $55). All together, the six recommendations would cost $1,756 and offer annual savings of $426, about 15% of our total consumption. Payback would be just over four years, and shorter if the government approves the local electric utility’s requests for rate increases of 16% over the next two years, or if natural gas prices rise again.
None of the improvements are very expensive, but each involves time and effort either to do it myself or to line up and manage a contractor. Like any home improvement project, there’s intrusion into your life, the mess to clean up and the potential for collateral damage. Results will be largely invisible and payback delayed, but the costs will be immediate and apparent.

I think you and I are more aware and responsible about energy than typical Americans. We’re much more likely to find and fix deficiencies, and when we replace an energy-consuming appliance, we consider the life cycle, as well as initial costs. But even we have our limits — these are incremental improvements of a house that is pretty good as it stands. Still, imagine the effect if we were able to reduce the energy consumption of every house by 15%.

If this were your house, what would you do?

E-mail Editor in Chief Paul Studebaker, CMRP, at [email protected].

Sponsored Recommendations

Arc Flash Prevention: What You Need to Know

March 28, 2024
Download to learn: how an arc flash forms and common causes, safety recommendations to help prevent arc flash exposure (including the use of lockout tagout and energy isolating...

Reduce engineering time by 50%

March 28, 2024
Learn how smart value chain applications are made possible by moving from manually-intensive CAD-based drafting packages to modern CAE software.

Filter Monitoring with Rittal's Blue e Air Conditioner

March 28, 2024
Steve Sullivan, Training Supervisor for Rittal North America, provides an overview of the filter monitoring capabilities of the Blue e line of industrial air conditioners.

Limitations of MERV Ratings for Dust Collector Filters

Feb. 23, 2024
It can be complicated and confusing to select the safest and most efficient dust collector filters for your facility. For the HVAC industry, MERV ratings are king. But MERV ratings...