Degrees Of Weatherization: Lab Finds Sweet Spot

Energy efficiency measures are often seen as low-hanging fruit, clever and perhaps less painful ways to reduce greenhouse gas emissions when compared to overhauling entire energy production systems. The International Energy Agency recently went so far as to call efficiency “the world’s first fuel.”

Not everyone buys it. The Breakthrough Institute folks, who, it must be said, seem to revel in saying nay to a lot of green doctrine, think efficiency’s GHG benefits are dangerously overstated, for instance.

image via Shutterstock

image via Shutterstock

Still, consider this from a new report from Lawrence Berkeley National Laboratory (aka, Berkeley Lab): Weatherizing the 113 million homes in the U.S. to the 2012 International Energy Conservation Code standard would save 3.83 quads in annual source energy, a $33 billion value.

Source energy, the lab notes, “includes site energy, the energy consumed by buildings for heating and electricity, as well as the raw energy required to transmit, deliver and produce it.”

To put 3.83 quads in perspective, it’s about three times the amount of wind energy the U.S. used in 2012, or nearly half the nuclear energy. Not chump change in the big picture.

More energy savings could have been found – there are varying levels of airtightness that homes can be sealed to and IECC was right in the middle of the ones the Berkeley team studied. But the researchers’ sense was that IECC was the Goldilocks standard, reducing airflow in home by a median value of 50 percent while seemingly being within real-world reach (unlike, say, passive house standard).

“As we move forward and look to build better housing stock, we want to know what standards we should enforce,” lead study author Jennifer Logue said in a statement.  “It looks like the IECC standard gets us the majority of the benefit of air sealing.”

The study didn’t drill down to make a hard determination of the cost of such an iniative – and if that sounds like an obvious next step, Logue agreed. “More research is needed to determine the costs of implementing each of these standards in new homes to see which are cost-effective,” she said. “As we get better at air sealing, we can move towards tighter envelopes in buildings.”

The study did take into account one energy downside of tighter buildings – the need for greater ventilation in order to maintain decent air quality. “We found that the energy burden would be pretty small, only about an additional 0.2 quads of source energy annually”—less than 0.1 percent of total source energy that goes to the residential housing sector—“to get everyone to the level where they’re getting enough whole-house ventilation,” Logue said.

“Energy impacts of envelope tightening and mechanical ventilation for the U.S. residential sector,” was published in the journal Energy and Buildings.

Pete Danko is a writer and editor based in Portland, Oregon. His work has appeared in Breaking Energy, National Geographic's Energy Blog, The New York Times, San Francisco Chronicle and elsewhere.