This article was originally published in the July/August 1999 issue of Home Energy Magazine. Some formatting inconsistencies may be evident in older archive content.
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Home Energy Magazine Online July/August 1999letters There is no relation between a full ASHI-level home inspection and an in-depth energy audit. There are similarities and even some crossover of components inspected, but the language (of Maryland's bill at least) would view an energy audit in the same way as an electrical or plumbing inspection. That is, conducting an energy audit does not imply an assessment of the overall condition of the house except where it affects energy performance and indoor air quality, whereas a home inspection does. And a home inspection does not attempt to determine any specific improvements, such as air sealing strategies or the cost effectiveness of conservation measures. There is no comparison between the two types of inspection. I would be amazed, especially since the law's founders had no such intention, if this law was applied to a sub trade such as energy auditors. If you feel the need to stress that you are performing an all-encompassing, whole-house performance inspection, then perhaps you need to provide a simple disclaimer.
Mark A. Fisher Tom Wilson responds: Mr. Fisher's recommendation is consistent with what we would like to see in Wisconsin. Unfortunately, the Wisconsin statute precludes such an understanding, stating that home inspector means an individual who, for compensation, conducts a home inspection, and, No individual may act as a home inspector ... unless the individual is registered under this subchapter. The law also specifically prohibits disclaimers like the one Mr. Fisher suggests. The only provision allowed is excluding a component of an improvement to residential real property from the inspection, if requested to do so by his or her client. Licensing, fees, testing, and annual training to meet the ASHI model are still required. Pool Cover Mysteries Uncovered I read with interest Miscellaneous Water under the Energy Bridge and the accompanying sidebar on pool covers (Mar/Apr '99, p. 8). The sidebar focused on features of pool covers--such as color, transparency, and insulation qualities--that affect pool convection and radiation losses and gains. However, a point was missed: the major benefit, by far, of a pool cover is simply that it prevents evaporation. Evaporation accounts for the majority of heat losses in most indoor and outdoor pools, and the enormous impact of pool evaporative heat loss is easily and often misunderstood. Free information, fact sheets, and pool energy analysis software are available at the U.S. Department of Energy's Web site, Reducing Swimming Pool Energy Costs, at www.eren.doe.gov/rspec.
Randy Jones The same question applies to the pool pump example, a 3/4 hp unit rated at 860 watts. Also, if the high example uses a grossly oversized 2 hp unit, rated at 39 gpm, it is hard to understand why the motor would draw 2,000 watts, as indicated, because the duty point of the pump load (39 gpm at some unspecified head pressure) is oversized--therefore the motor is not working hard, it's hardly working. Pardon my kibitzing, because Home Energy is one of my must reads, but if there are other assumptions that underlie this matter and lead the author to conclude the wattage values shown, I would like some clarification.
Bill Powell Home Energy's technical editor, Steve Greenberg, responds: Your math is correct, but as you state, you're ignoring motor efficiency. At 100% efficiency, a motor will consume 746 watts of electrical input power per horsepower of mechanical output. But real motors--especially the relatively small, single-phase ones used in residential equipment--are significantly less efficient. The well-pump motors in the table were assumed to be 57% and 62% efficient for the 1/2 and 3/4 hp units, respectively; the pool pump motors, 65% and 75% for the 3/4 and 2 hp units. These efficiencies are pretty typical for the most common standard-efficiency motors in these applications (there are high-efficiency versions of these available with about 10 percentage points higher efficiency). Regarding the high pool pump estimate, you are correct that if both pumps are connected to the same pool system and have the same flows, then if the 3/4 hp unit is fully loaded the 2 hp unit would be running below 40% of full load. What we neglected to point out is that many oversized pumps are pumping more than the desired flow. In such applications, the pumping power required scales approximately with the cube of the flow, thus selecting a pump that would create 54 gpm instead of 39 gpm would create the difference between 3/4 hp and 2 hp, asssuming the pump efficiencies are equal. Thanks for helping to clarify these points.
We have promoted the combination of guarantees and performance testing as a key mechanism in ensuring quality control in the achievement of energy-efficient homes since the inception of our program in 1990. Since that time, we have certified more than 35,000 homes as energy efficient and have taken part in programs sponsored by utilities (both electric and gas), builders, and manufacturers. This makes us, I believe, one of the largest energy guarantee providers in the country.
Frank Mayberry
Walter Ahlgrim Helen Hunter responds: Ameren decided not to renew their contract with VoltView Tech in December 1998, after the issue went to press. It is possible they will reconsider offering it again this year. Your best bet may be to try one of the programs anyone can use, such as Lawrence Berkeley National Laboratory's Home Energy Saver at http://eetd.lbl.gov/hes, or one of the others listed in the article.
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