WINTER IS ON THE WAY, WHAT ARE YOU GOING TO DO ABOUT THIS?

Weatherizing Homes to Uniform Standard Can Achieve $33 Billion in Annual Energy Savings

With winter around the corner some homeowners may be thinking about plugging all the leaks in their home to make them less drafty. Imagine if every homeowner in the country did that-how much energy could be saved? 

Using physics-based modeling of the U.S. housing stock, researchers found in a new study that upgrading airtightness to a uniform level could achieve as much as $33 billion in annual energy savings.

Currently people who weatherize can get their homes about 20 to 30 percent tighter. But they're not sealing all the cracks. There's still quite a bit left on the table, and those extra leaks and cracks could potentially save a lot of energy. Energy impacts of envelope tightening and mechanical ventilation for the U.S. residential sector. while researchers need to figure out how much energy is wasted from leaky homes and determine the optimal standard of airtightness-one that would maximize energy savings while minimizing the cost of achieving those savings.

This is an important question because the residential sector-113 million homes-uses about 23 percent of total U.S. source energy annually. (Source energy 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.) Heating and cooling accounts for about half of the site energy used in residences.

The largest potential savings are in the hottest and coldest climates. As new air enters homes through leaks and cracks, it has to be cooled or heated. Although the trend has been towards building tighter houses, the science is still not settled on the best ways to minimize leaks. More research is needed to figure out what are the most effective ways to weatherize.

The 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.

The analysis in the study factored in the energy costs of increasing ventilation where necessary to maintain good indoor air quality. A separate analysis looked at the energy cost of only bringing the housing stock into compliance with ASHRAE 62.2, a national ventilation standard for homes that ensures sufficient ventilation for human health.

Leave us a comment on what you are doing to achieve a tighter, more energy efficient home this winter.