Insulation Institute Blog

By Michael Schettine, Technical System Expert

New Housing Energy Requirements

The ante has been raised by states adopting the 2015 IECC energy code, and builders are scrambling to meet new requirements.

A large part of the new requirements involve envelope air leakage standards. Simply put, the house (envelope) air leakage, when tested at 50 Pa pressure differential, ‘shall not exceed’ 5 air changes/hour (ACH) in U.S. climate zones 1 and 2 (warmer areas) and 3 ACH in the remaining cooler zones 3-8. New homes must be tested, and those meeting the requirements will receive a “Certificate of Occupancy,” which will be necessary for sale of the structure. Because the building must be largely completed before the testing can be performed, builders get one shot at achieving the air leakage standards, if the building doesn’t pass, costly rework and retesting must be done to ensure compliance with code.

Insulation Institute has been focusing of late on the topic of air sealing and what it takes to construct a home that is airtight using the “3 Ps,”  — People, Practices and Products. Proper air sealing is critical for meeting stringent air change rates required for green building targets such as HERS, Energy Star, Net Zero or Passive House.  While there’s a plethora of guidance available on air sealing from many sources within the building industry, the best guidance to convey to the various contractors involved in home construction can be distilled to this: air seal “like a boss.” That is to say that everyone involved in the construction of that home has a role to play and their role should not be viewed as that of a “jobber” but a “boss” when it comes to air sealing, because getting to stringent targets requires that one think “holistically” versus individually.

Among the trickier areas to properly seal and insulate is around electrical boxes. These can often be sources of air leakage and are notoriously hard to properly insulate with batt products without excess compression. A new product, box shell, seeks to address both of these problems. As the site shows, the “shell” fits neatly around the electrical box, flush with the sheathing behind and affixed easily with a staple gun. From there, you can just cut a full notch out of a fiber glass batt and install it around the shell, then fill the area between the shell and the box with low expansion canned foam to seal it up. The company, still in its infancy, is offering single, double and triple junction box shells, all for under $2. Using these could help reduce concern that an evaluator, whether a building inspector or HERS rater, will ding you for problems around this typical trouble spot. A couple bucks for that peace of mind is probably worth it.

Energy Efficient homes are in high demand among consumers and are a business imperative for builders who want to remain competitive. Air sealing is critical to achieving energy efficiency.  But, when it comes to air leaks within a home, all points of entry are not created equal. Big holes in a building enclosure are easy to avoid, identify and fix, but smaller holes have proven to be a big problem.  For any building to meet ever more stringent energy efficiency targets, all gaps and openings in a building enclosure should be air sealed.  However, with so many possible air leakage points, and limited time/money to devote to air sealing, builders need to focus on getting the most bang for their air sealing buck.