With all the talk nowadays about the importance of making our homes as airtight as possible, people are understandably confused about whether their home can be too tight, leading to poor performance and air quality. In fact, this is one of the most common questions we get from homeowners. The answer is different depending on whether the question is about an existing home or one that is being substantially renovated or newly constructed. Let's first consider Rye's large stock of existing homes, many of which are more than 50-years old.

In existing homes that rarely were built with energy use in mind, homeowners already experience the effects of a home that "breathes"—with sky high fuel and electric bills, chilling drafts, layering on sweaters in the winter and dampness in the summer. Letting the house "breathe" as a result of inadequate air sealing and traditional forms of insulation is another way of saying "let the air move in and out of the house wherever and whenever it wants," resulting in excessive use of energy to heat and cool the home.

A high quality professional air sealing job (called "blower door assisted air sealing") is a low cost and highly effective way to begin to mitigate the problem.  A blower door fan is used to measure the air flow through the home before, during and after the sealing process. But no matter how expert the job, unless the house were actually de-constructed, air sealing cannot take place behind walls, between sill plates, or around doors and windows that were accessible when the house was built. Thus, a professional air sealing job in an existing home will make a noticeable difference in energy use but is highly unlikely to make the home "too tight."

If an owner of an existing home also has high performance insulation such as cellulose or spray foam installed in accessible spaces in attics, basements and crawl spaces, creating an air barrier in those key areas, further meaningful energy savings will result but, again, the house is not sealed to the standard that would occur in a newly built or gut renovation.  

But let's consider a home under construction.

For professionals working to enhance energy efficiency in our homes, the mantra is "Build Tight, Ventilate Right," which refers to the importance of using extensive air sealing during each step of the construction process as well as the use of high performance insulation that is an air barrier, such as cellulose or spray foam. As the house is framed, caulks and sealants are applied to all of the locations on the exterior walls and roof where materials are joined. All plumbing, electrical and other penetrations of the building envelope are also sealed. The house may well be sheathed in rigid foam, including the walls and roof. Vapor barriers should be installed under the slab and high performance cellulose or spray foam used as insulation with a goal of closing every possible source of air movement between the outside and inside of the finished home.  

Once these steps are taken, home builders must also consider the second half of the statement: "ventilate right." Homes being built to the highest energy efficiency standards today install whole house heat-recovery ventilation (HRV) systems to provide constant controlled air flow. Heat is recovered from the exhaust air and used to pre-heat the incoming fresh air flowing through a ventilation system that covers the whole house, improving air quality and enabling proper venting of combustibles such as fireplaces and gas ranges. Use of these stringent techniques together with other energy efficiency measures can dramatically reduce the energy use of a new home.

Judith Martin is the founder and principal of Green Home Consulting, located in Rye, which focuses on the growing interest in the home-building and remodeling marketplace for environmentally sensitive homes in Westchester and southern Fairfield counties. Green Home Consulting also works with owners of existing homes to improve energy use.