What’s in an I-beam? Architects all over the world design houses that rest on them. Engineers test and refine them; builders use them in everything from simple bungalows to soaring cathedral ceilings.
But making I-beams out of the usual materials—wood, steel, aluminum—uses a significant amount of natural resources. Trees are cut down; metals are smelted at high temperatures.
When students and faculty at Santa Clara University began planning a house for the U.S. Department of Energy’s Solar Decathlon, they were looking for a material to make I-beams that would be more sustainable.
That’s when Mark Aschheim, associate professor of civil engineering, had an idea. He was involved in another University project in El Salvador, helping to rebuild housing after earthquakes ravaged that country in 2001. One of the problems he had confronted was the necessity of importing steel building products from Mexico, an expensive and not very energy-efficient proposition.
Because El Salvador has largely been deforested, wood was not an alternative. But the Salvadorans do grow bamboo. Aschheim knew that bamboo has been used for centuries as a building material in Asia. Growing up in Singapore, he had seen unprocessed bamboo used as a weight-bearing member.
|Toting the bamboo I-beam are, from left, SCU engineering students Ray Lam, Meghan Mooney, Andrew Smith, and Katherine Powell. Photo: Charles Barry|
Working with engineering students, Aschheim determined that it was possible to laminate sheets of manufactured bamboo flooring and then to form a cross-section out of this material, which could be used as a beam.
Bamboo has many advantages for those who care about the environment. “You can harvest the shoots every three to five years. That’s so much better than a tree, which takes 30 to 50 years to reach maturity,” Aschheim says.
Last September, visitors to the WIRED magazine NextFest got a sneak peek at the bamboo I-beams. Held in New York City, the four-day exposition of innovation featured technologies and products that have the ability to change our world.
According to junior civil engineering major Raymond Lam, who has worked closely with Aschheim in testing and perfecting the beams, “Santa Clara is the first in the country to have bamboo qualified for structural support” in a house. The University has applied for a patent on the process.
Building a sustainable house, the decathlon team understands, is more than throwing a few solar panels up on the roof. Every material must be considered in terms of its energy efficiency—and that means more than just whether it conserves energy once it becomes part of the construction.
For example, the team was originally interested in using a particular external paneling that was environmentally friendly. One hitch: The paneling was produced in Europe. “When the team did further investigation into the matter,” says project manager James Bickford, “we realized that the carbon cost to ship this material across the ocean and then to truck it to the University was much greater than the good made up by the clean material.”
Bickford goes on to explain, “Every part of the house has a life cycle from the time it was a raw material, through processing, distribution, and then shipping and assembly. This life cycle produces waste all along the way, and while this may not be apparent at the end result, it is still a very important consideration in sustainable design.”