This article was originally published in the July/August 1998 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 1998
The True Test Is in the Real WorldIn this issue of Home Energy, you'll find several articles and news briefs describing scientific studies of the energy performance of various technologies. We've pulled together findings on insulating concrete forms (ICFs), dishwashers, duct sealants, and wall insulation, among other technologies. The articles are useful on their own, but together, they offer a second message that is as instructive as the individual articles.
These research projects were undertaken by several types of institutions. ICFs were studied by a trade association, the Portland Cement Association (PCA). Consumers Union, publishers of Consumer Reports, compared dishwashers. The National Association of Home Builders (NAHB) Research Center sought to compare the efficacy of different insulation techniques in reducing air infiltration. Finally, the public sector contributed a study, as Lawrence Berkeley National Laboratory (LBNL) tested the longevity of duct sealants.
Each research group started with implicit assumptions and perspectives that influenced their results and recommendations. While we do what we can to cut through to the facts, readers still need to be critical, as the following vignettes demonstrate.
In the NAHB comparison of insulation technologies (page 11), homes insulated with fiberglass batts appear to have the same infiltration as those insulated with dense-pack cellulose. The study explicitly assumed that homes would have comprehensive air-sealing, which is questionable to begin with. It also assumed that the same R-values on the package would mean the same R-values in the wall. Our experience, which their findings bear out, suggests that batts are much less likely to be correctly installed. Poor installation can have a major effect on R-value.
A similar situation appears in the LBNL study comparing the longevity of duct tape versus other sealants (see page 14). It wasn't possible for the study to simulate the oil, dust, and grime that ducts build up in the real world. The authors noted such differences, but since there are so many variables in field use of such products, users should always be on the lookout for other problems that may not appear in such lab studies. It is also unfortunate that government policies forbid naming brand names. The findings clearly show how institutional rules affect research results.
The article on insulated concrete forms (page 27) is a careful study but, given the source of the research funding, the results must be read with extra skepticism. Not surprisingly, the research demonstrated that ICFs provide a tight, well insulated, and satisfying home. Again, there were implicit assumptions, such as proper installation by qualified crews. Questions like How do you deal with the foam forms bulging during the concrete pour? were not discussed in the original study. The solution--shaving off some of the foam--would likely affect the wall's R-value. This sticky issue is also left out of the discussion.
Finally, in Conservation Clips, Consumers Union reports that the EnergyGuide ratings of dishwashers equipped with dirt sensors were misleading. Consumers Union is admirably independent, and their test procedures do not suffer from corporate influence. They compare products based on real-life conditions, and list the brands actually tested. But this approach only works because Consumers Union compares mass-produced products, not techniques or procedures.
We at Home Energy try to give you the perspective and context so you can judge the value of scientific results. But we can never cover all the angles. As our Field Notes column (page 41) reveals, even the most promising research results take second place to real-world uses.
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