by Guest Author Jono Sher

In these times of economic hardship, there has been a real push towards energy efficiency in all sectors. This is in large part due to the fact that the most gains to be had are from minimizing losses and taking advantage of the ‘low-hanging fruit’ or, as my fellow energy auditor colleagues say, ‘fruit lying on the ground’ that is conservation. Most of the residential East Coast was built in the early part of the 20th century and pre-dates much of the common knowledge we now share about building science. The most fundamental part of building science is rooted in air exchange, or the natural pathways of air as it travels from outside to the inside and vice versa. The amount of air that a home exchanges from inside to outside is measured in “air changes per hour” with an air tight home turning over ¼ of its air every hour, whereas a leaky home would exchange all of its air within an hour. The majority of residential energy costs come from heating a home in the winter, and if your home is losing all of its air within an hour’s time, it will be extremely expensive to continue to heat that space. Hence the importance of creating air barriers, or air sealing, which is essentially blocking air where it might otherwise be leaking into a home. Oftentimes, this is the most cost effective way to improving a home’s energy efficiency because most of the sealing can be done with simple silicone caulk or spray foam.

Doors and windows are notorious leakage areas that can be difficult to improve. Cracks around windows can be caulked, and doors can be weather-stripped on the inside and outside of the frame. Storm doors and windows can drastically reduce the air leakage areas, but the return on investment is not nearly as high. Common leakage areas in buildings include plumbing and gas line penetrations into walls, baseboards, dryer vents, chimney and combustion equipment exhaust flues, as well as any framing transitions in the walls, especially where parts of a home may have been added on post-construction.

It may be difficult to pinpoint where these leaks are occurring without the benefit of a blower door test, a common depressurization test performed by national Home Energy Rating System (HERS) raters or energy auditors. In the most simplified terms, the test depressurizes the home to a preset negative pressure in order to accelerate air flows under normal conditions. This way, the fan is blowing out a certain amount of cubic feet per minute, and that air must be replaced by other air, which makes its way in through the openings in the home. Without this test, it is difficult to assess exactly how much an area may be leaking or where it is leaking if at all. Silicone caulk is good for sealing up gaps of a half-inch or less, while gaps larger than that require the expanding qualities of spray foam. As hideous as it may look aesthetically, spray foam is an energy efficiency dream as it both seals air and insulates at the same time. Plus, the next day when it dries, it can be shaved off and painted over so as not to leave unsightly looking spray foam all over your home. With $20-$30 in caulk and spray foam, a home’s air exchange can be reduced anywhere from 20%-50% and next year’s heating bills will be a fraction of their former selves.

- Jono Sher is currently an energy auditor, green building consultant, and building performance analyst working with Elysian Energy and the DC Department of Environment Free Home Energy Audit Program for all homeowners within the District of Columbia.