Energy Adviser: New homes built tight, ventilated right, too



Homes constructed before the 1970s were allowed to breathe, which means a lot of cold air seeps in and heated air leaks out throughout the year. In those days, energy was cheaper and plentiful. Builders started sealing houses tight as a response to the 1970s energy crisis; unfortunately, that effort had unintended negative consequences.

It turned out that these new tighter houses developed moisture and mold problems as moist air that used to leak out of the house now stayed in. Tighter houses also increased the chance that combustion appliances such as fireplaces, gas furnaces and water heaters could back-draft poisonous exhaust into the living space. Poorly ventilated houses could also allow cancer-causing radon levels to build up.

“Pre-1970 homes ‘breathed’ air in and out continuously,” said Mike Selig, program manager for the county’s Weatherization and Building Safety programs. “The energy crisis sealed houses up and one of the results in the Northwest was a dramatic increase in mold and dry rot.”

Unless updated, ’70s and early-’80s homes in Clark County may still harbor damage caused by moisture in the walls. Poorly ventilated ones may also trap in bad air. Such homes can even impact respiratory problems or allergies. A 2007 Environmental Protection Agency study linked 4.6 million asthma cases to dampness or mold in homes.

Today, the new mantra for builders is “build tight and ventilate right.” The field of building science was developed after the negative effects of tight building construction were discovered and is now the model for producing energy-efficient, healthful housing. Treating the home as a system, builders have developed ways to save energy, improve ventilation and decrease moisture problems by improving air circulation in and out of a home.

Gaining from crash of ’08

The building crash of 2008 eventually caused Clark County to be farther along in integrating building science and building safety than most other communities, Selig explained. “Clark County had to slash its building staff significantly; some of our building inspectors went to work in energy conservation businesses,” Selig said. “In 2010, they returned primed with building science training they had picked up while they were away.”

Another positive result of the building crash was the formation of partnerships to do more with fewer resources. Clark County Building Safety works with Clark Public Utilities, Clark County Building Industry Association, the Washington Department of Commerce, DOE and HUD to elevate awareness of building science in local organizations. These groups also provide training for builders in energy conservation, new building techniques, heating and ventilation as well as a code checklist and other materials to make their work easier.

Many local builders today are on the forefront of green homebuilding. They build for the home site, and employ building science to design and erect comfortable, energy-efficient homes that are healthful to live in. They understand homes with different exposures have differing energy-saving and moisture-blocking needs, as do homes built under shade trees, or those on the Columbia River with greater exposure to rain and wind. As technology and our understanding of how houses perform continue to evolve, houses will become even better. Energy efficiency, indoor air quality and building durability will continue to improve.

“The marriage of building science and building safety has been a very good thing, and like a good marriage, gets even better with age.” Selig said.

Energy Adviser is written by Clark Public Utilities. Send questions to or to Energy Adviser, c/o Clark Public Utilities, P.O. Box 8900, Vancouver, WA 98668.