Doug Garrett pointed out that while the International Energy Conservation Code (IECC) is calling for tighter and tighter air-sealing standards, it is completely silent on combustion safety testing (see "Code Conflict," JLC 9/13). The energy code allows builders to install natural-draft combustion appliances in a home with no safety testing.

In existing homes, the issue of combustion safety is perhaps an even greater concern, but it's not well addressed here either. As John Krigger, a principal at Saturn Resource Management and a leader in weatherization and home performance training, explains: "The Building Performance Institute (BPI) and the Residential Energy Services Network (RESNET) require  worst-case tests but don’t require a complete combustion analysis measuring CO, O2, and temperature" (see "Effective Combustion Safety and Efficiency Testing"). According to Krigger, worst-case CO testing, which has dominated weatherization and home-performance training and certification, is too complicated, inconsistently performed, and often not followed by effective combustion-safety improvement. In the blog post cited above, Krigger offers a much simpler procedure for evaluating the combustion safety of natural-draft gas appliances - procedures that ought to be followed whenever tightening up a home with natural-draft water heaters, furnaces or boilers, even if it's not required.

Carbon monoxide (CO) is frequently called a "silent killer" (see, for example, "Carbon monoxide poisoning: 5 things to know about the 'silent killer,'" CBC News, 3/18/14). This time of year you can search Google news and find a dozen or more reports of recent deaths caused by CO in homes. CO accounts for an estimated 500 deaths in the U.S. each year, although only about 170 of those come from non-automotive sources, according to the Consumer Product Safety Commission's  "Carbon Monoxide Questions and Answers." Non-lethal levels of CO exposure, however, may affect a far greater population. The health effects of chronic exposure to low-level CO have been known for some time (see  "Recognition of Chronic Carbon Monoxide Poisoning," Wisconsin Medical Journal, 9-10/1999; PDF).

While carbon monoxide is a clear hazard in homes, radon is even worse. The National Academy of Sciences estimates that 15,000 to 22,000 die every year from radon-related lung cancer (see the EPA's "Health Effects of Radon"). It's not a hazard everywhere; it depends on local geology and exists in some regions of the country more than others (see EPA radon maps). But if you live in radon country, concentrations of the deadly soil gas can build up in tight homes, increasing the risk to occupants.

In new construction, there are easy solutions (see "Radon Venting—Do It During Construction or Add a Zero," Energy Vanguard, 7/10/13). In existing homes it's a little more complicated. The techniques that have been out there for a long time still rely on subslab depressurization (see "Radon Reduction Techniques for Existing Detached Houses," EPA 10/93; PDF)  This is obviously harder to accomplish once the slab has been poured. If no slab exists, a heavy plastic membrane can be installed over a dirt basement or crawlspace, and soil gases ventilated from under the membrane to the exterior. This is no small trick to do effectively, which makes it a relatively expensive procedure compared to air sealing by itself.

Increased costs of weatherization in radon country may be the reason the Federal government has been slow to release the results of a study commissioned in 2010 for Weatherization Assistance Program (WAP). As reported in Environmental Building News (see "Pushing Weatherization, Feds Look the Other Way on Radon," EBN 3/4/14): "Researchers published pre-weatherization data in December 2011 showing that 12% of the homes slated for weatherization had radon levels above the EPA action level of 4.0 picocuries per liter (pCi/L) based on short-term tests; the vast majority of homes were below 1.0 pCi/L. Although post-weatherization testing was conducted just a few weeks after the baseline testing, those follow-up results have never been published."

Professor William Angell, chair of the Radon Prevention Working Group at the World Health Organization, suggested in the EBN article that the issue might be cost. While there are limited funds for weatherization, there are no funds currently available for radon mitigation. According to a WAP supervisor quoted in the article, the DOE research results, initially due in December 2013, may come out later this month. The delay, EBN reports, is likely due to a reassessment of EPA and DOE  policy.