While studies have shown that properly built unvented crawlspaces stay much drier than vented crawlspaces in mixed-humid climates, questions remain about their suitability and energy use in other parts of the country. To get some answers, researchers from Advanced Energy — a Raleigh, N.C.–based nonprofit research and testing company under contract with the U.S. Department of Energy — recently monitored two sets of new homes in two different climates: a 15-home modular housing development in hot, humid Baton Rouge, La., and 12 stick-framed homes in cold, dry Flagstaff, Ariz.

At each site, four control homes were built with locally code-compliant vented crawlspaces. In Baton Rouge, hvac ductwork was located in the attic of the control homes; in Flagstaff, it was put in the crawlspace. Researchers measured crawlspace humidity and energy use in both the test homes and the control homes for more than a year in Baton...

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