Now, a brief respite from talk of carbon emissions and the American shale boom with a look at the demand side of the energy equation. Researchers at Lawrence Berkeley National Labs have calculated how much energy and money Americans would save by weatherizing their homes, and it's quite large: $33 billion a year:

The Berkeley Lab researchers considered five levels of tightening: “average” tightening, “advanced” tightening, the International Energy Conservation Code (IECC) standard, the R2000 standard (common in Canada, tighter than IECC) and the “passive house” standard, the tightest and most difficult to achieve.

They found that upgrading all homes to be as airtight as the top 10 percent of similar homes (advanced tightening) would decrease energy demand by 2.6 quads annually—out of the total 22 quads of source energy used by the residential housing sector—leading to roughly $22 billion in savings in energy bills. Reaching the IECC standard would yield savings of 3.83 quads in annual source energy, yielding $33 billion in savings.

The study found that the IECC standard offered most of the benefit that the tighter standards would yield. Moreover this standard is likely more achievable than the tighter standards. According to their analysis, raising the U.S. housing stock to the IECC standard would reduce airflow in homes by a median value of 50 percent.

For some perspective, the United States uses roughly 100 quads of energy each year, so their low end estimate is about 2.5% a year.

Residential energy efficiency is tricky because you're balancing several competing factors to reach an optimal outcome. You want to reduce the amount of air leaking into or out of a house while also making sure there is enough fresh air coming in, and you want to find upgrades that save more money than they cost to implement.

From their research, it looks like the IECC code goes a long way to reaching that optimum, and I know that the City of Austin (where I live) updates its energy efficiency code every couple of years based on IECC. Although here in Austin we're less concerned with winter coming than surviving hot summers. But either way, energy efficiency is an important tool to have in the bag.