SciLights:The Life of a Building
I think a lot about building energy use and how it contributes to the UNC Chapel Hill carbon footprint, but there’s a major energy user I can’t track because there are no meters in place to measure it.
I’m talking about construction. The University has grown dramatically over the last 10 years, expanding the built environment by over 40%. We now tip the scales at over 17 million square feet, all of which must be heated, cooled, and powered. But what about the actual act of building? Have you ever wondered how much energy it takes to manufacture all of that cement, rebar, brick and glass, and how much diesel the machinery takes to put it all together.
Well, wonder no more, because a new paper out in Buildings and Energy answers that question precisely. The authors Oyeshola F. Kofoworola and Shabbir H. Gheewala, use a technique called “Life Cycle Energy Analysis” (LCEA) to estimate the amount of energy it takes to guide a project from raw material to life to landfill. And I’ll even spare you their eye-burning pie charts.
A quick glance at the building’s life cycle shows that over 80% of the energy is consumed during the building’s useful life on operations like heating, air conditioning, and electricity. It stands to reason that a little extra investment in efficiency during design and construction may go a long way toward decreasing the long term cost of ownership.
The second thing you’ll notice is that manufacturing makes up more than 15% of the total. With a contribution that large, it’s probably important to include this life cycle view into decision making about how much we build and which materials we choose. It might be possible to shrink the energy footprint of a building through the use of recycled content or rapidly renewable forest products.
Are you wondering which materials to target first? Well, the authors are way ahead of you.
From an energy standpoint, steel and concrete dominate. This shouldn’t be surprising, because these two components provide much of the structure of a modern office building. But when you compare their energy consumption to the total amount of material in the building, you see that steel is disproportionately carbon intensive. There are a few ways to make steel, but you can bet they’re all energy intensive.
There’s a lot more meat in this paper, so be sure to check it out (or head to your local university for free access!) As for me, I’ll sleep better knowing that someone out there makes a living answering my deepest questions.
Source: O.F. Kofoworola, S.H. Gheewala, Life Cycle Energy
Assessment of a Typical Office Building in Thailand, Energy and Buildings (2008),
doi:10.1016/j.enbuild.2009.06.002
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