Huff and puff

Energy efficiency in practice In YS straw homes

By Lisa Bennett

Roughly 2.6 million years ago, our ancient ancestors began building straw homes on the vast African Plains. Over time, other cultures also began using straw as a construction material in their homes. From Germany, to England, from Asia to North America and beyond, anywhere grasses grew, people used them for insulation and building. The material was so common, in fact, that it was reflected in literature around the world. The nursery rhyme, “The Three Little Pigs,” printed in “The Nursery Rhymes of England” (London and New York, c. 1886) is a good example. One can’t help but wonder if the author, James Orchard Halliwell-Phillipps, would be surprised to find that his iconic, failed straw house would later become the house of the future.

The home of Bob Brecha, a professor at the University of Dayton and the research director for the Hanley Sustainability Institute; School of Engineering, Renewable and Clean Energy Graduate Program, is a far cry from the storybook straw house and even that of his ancient ancestors. His home—a modern, straw bale constructed house—is arguably one of the best-insulated types of home in the U.S.

“For a house this size, we use about 75-80 percent less energy than a typical house,” Brecha says.

And no wonder. Straw bale homes are designed to minimize thermal bridging and convective currents that cause heat loss throughout the home. R-values (a measurement of thermal resistance in a given material or set of materials) for straw bale homes far exceed those of more standard types of homes. For example, a typical R-value for a traditional, fiberglass-insulated home is about R-19. The R-value for a straw bale home, by comparison, is a toasty R-30 to R-33, which means that there is a lot less heat being lost.

“Last winter—and it was a cold winter—our heating bill for the whole season was $150,” Brecha says.

But how do straw bale home stack up against a typical stick-built home? Pretty well, actually.

“The building costs are about the same as building a regular house,” Brecha says. “The building materials are cheaper, but the labor is more. So it balances out.”

Ok … so it costs about the same to build. But what about all that straw? Wouldn’t it mold over time? The answer is pretty surprising. According to Brecha, mold isn’t an issue. The straw is dry when it’s packed in and then covered with a type of clay plaster to keep it that way.

“It turns out that the clay plaster that’s put on it is actually hydroscopic,” he says, “so if there’s moisture in the walls from humidity, it wicks it away, keeping it free from mold.”

Now that’s ingenuity! But wouldn’t all that really dry straw be a fire hazard? Once again the answer is shocking: It’s not a hazard at all!

“There is a group called Oakridge National Laboratory that has done the standard fire testing on straw bale walls that they do on other walls,” he explains. “And the straw bale walls do at least as good or better than the standard two-by-four stick construction. There is a qualitative view that says that this material is packed into the wall so there is very little available oxygen.”

And we all know that without enough oxygen, a fire would have a really hard time burning. And that’s good news for owners of straw bale homes.

Straw bale homeowners and builders, Andy and Beth Holyoke of Yellow Springs, are thrilled with their home.

“What I like most is that the plastering lends itself to lots of creativity and softness,” says Beth. She and her husband Andy became interested in straw bale homes after attending a workshop on them in Olympia, Washington.

“When we came back, we read lots and lots of books and did lots of research,” she says. “He used that knowledge to build one for his mom about 16 years ago.”

Since then, they have constructed about nine straw bale homes in Yellow Springs, including one for themselves. “We build smaller homes, about 1,000 to 1,500 square feet.” Beth says.

Like most straw bale homeowners, both Beth Holyoke and Bob Brecha did lots of homework before building their homes.

“The thing I want people to know is that straw bale technology has changed over the past 20 years so a lot of older books don’t have the updated technology information,” she says.

Though there are lots of books with more up-to-date information available at the library, sometimes the best way to really get the information you want, is to just go see one for yourself. “In the first weekend of October every year, there is the Green Energy Ohio solar tour, but it really has turned into more of an alternative energy and energy efficiency tour,” says Brecha. “And so my house and some of the other houses have been open during those tours.”

For more information on the Green Energy Ohio solar tour, visit:

Reach DCP freelance writer Lisa Bennett at

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Reach DCP freelance writer Lisa Bennett at

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