Steel vs. wood framing – More food for thought
I recently read a good steel vs. wood column posted by Michelle Kauffman on January 14th (http://blog.michellekaufmann.com/?p=1793), and thought I’d put forward a bit of the research we did when thinking about the wood vs. steel question. One of the most comprehensive articles I have read on the subject can be found in a study called “Life-Cycle Energy Use in Office Buildings” by Cole and Kernan, 1996. It is a study funded by Natural Resources Canada that examines:
- Energy to initially produce the building;
- The recurring embodied energy required to refurbish and maintain the building over its effective life;
- Energy to operate the building—the energy required to condition (heat, cool and ventilate) and light the interior spaces and to power equipment and other services; and
- Energy to demolish and dispose of the building at the end of its effective life.
The study—although done using commercial buildings rather than residential homes for its examination—makes some interesting points. In particular, it points out that not only do we need to think about embodied energy in the steel & wood products, and operating energy, but the recurring embodied energy required to maintain the building over its effective life. Taking this into account potentially makes for an improved argument for steel framing.
One of the last quotes from the article reads:
“Depending on the effective life of a building, the initial embodied energy may be greater or less than the recurring energy associated with refurbishment and repair. Over a typical 50 year building life, the initial embodied energy of the structure represents a relatively small portion of life-cycle embodied energy (i.e. less than 5%) and, as a consequence, the distinction between wood, steel and concrete systems is also less marked. Reducing embodied energy involves much more comprehensive design approaches than materials’ substitution. Since the recurring embodied energy figures associated with materials’ replacement and repair are significant, attention must be focused on materials’ longevity and the ability to replace elements within a total building assembly.”
Perhaps at the scale of a residential home this makes less of a difference. But, if we are building for durability over time and intend our homes to last hundreds of years, perhaps steel does offer at least some benefits not taken into account by initial embodied energy.
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