One of the key components of sustainable homes and buildings is a thermally efficient and dry building envelope that minimizes the leakage of air through the home. Air leaks in walls and attics decrease occupant comfort by permitting the entrance of cold or hot air, depending on the season.

As energy costs continue to fluctuate, homeowners are seeing the benefits of becoming more eco-savvy. One growing area of focus is weatherization. When you consider that up to 40 percent of a home’s energy loss can be attributed to air infiltration*-a combined with recent government incentives-it’s easy to see why.

Air leakage is the unplanned, unpredictable and unintentional airflow across the building enclosure. This makes air flow control important for several reasons: to avoid air transported moisture and moisture damage, to reduce energy losses and to ensure occupant comfort and health.

The renewed emphasis on energy conservation in building codes has led to increased awareness of the importance of controlling air leakage of buildings. One of the most effective ways to conserve energy is to provide an airtight building envelope.

Water testing is complicated and as a contractor, if you have never had to be subjected to it, you can count yourself lucky. Water testing has made exterior plaster and EIFS work anything but business as usual.

Over the next three years, builders and contractors will witness an unprecedented rise in energy-efficient construction. Energy efficiency advocates succeeded in tightening the 2009 and 2012 International Energy Conservation Code with an estimated 30 percent improvement between the 2006 and 2012 versions of the code.

With changing energy code requirements, as represented in ASHRAE 90.1 or California’s Title 24, designers, engineers and contractors are facing practical challenges trying to meet these higher standards. One approach that is prescribed is the use of continuous insulation on the outside of building framing.

When a building leaks, the design, workmanship and material of the building envelope are all suspect. The exterior walls, roofing, windows, doors, balcony decks and below-grade waterproofing are all potential culprits. Oftentimes, however, a leak cannot be attributed to just one building envelope component.

As building materials and methods become better at sealing air leaks, the question arises, “How tight is too tight?” In terms of energy efficiency, one cannot build too tightly. Reducing air leakage is critical to lowering heating and cooling energy consumption.

The University of Pennsylvania’s advocacy of sustainable design extends from LEED ratings targets for all new building projects to collaborative efforts between the Division of Facilities and Real Estate Services, the campus community and the City of Philadelphia.