Conventional engineering wisdom à la “The Three Little Pigs” suggests that straw houses aren’t exactly sturdy. But Darcey Donovan, right, has turned that fable on its porcine ear.
Moved by the devastating 7.6 earthquake that struck Kashmir in 2005, killing 75,000 people and destroying the homes of more than 3 million, Donovan, ’86, founded Pakistan Straw Bale and Appropriate Building in 2006. The nonprofit aims to create low-cost, durable buildings in rural areas that are subjected to earthquakes and extreme weather. In March, Donovan and her colleagues demonstrated just how robust a straw-bale house can be.
They constructed a 14-by-14-foot building from straw bales covered in a clay plaster. The house’s nemesis: a shake table at University of Nevada, Reno, which can simulate the ground acceleration recorded from specific earthquakes. After beginning the test with a 30-second low-grade quake, Donovan and her team gradually ratcheted up the seismic activity to reproduce the severe shaking recorded during the 1994 Northridge, Calif., temblor. “It was so exciting . . . like being at a sports event, where you’re rooting for your team up there on the table,” she says.
The building did not disappoint its fans. After the shake table’s ground acceleration peaked at 0.8g (double the force of Northridge), it created significant cracks in the walls but did not bring the house down. Donovan notes that in addition to its hardiness, the construction method is about 50 percent less expensive—and 80 percent more energy efficient—than conventional earthquake-resistant construction. So far, the nonprofit team has helped construct 11 straw-bale buildings in Pakistan.
Still, when it comes to straw houses, there is one enemy, and it’s not a blustery wolf. “Moisture is the biggest challenge,” Donovan says. “You can’t let it get wet, or the straw will mold.”
SANDRA A. SWANSON is a science writer in the Chicago area.
