Are New England Homes Being Built Too Tight?
I recently read an article on Energy Conservatory.com, that asked the question: Are Your Houses Too Tight? Written By Gary Nelson, Robert Nevitt and Gary Anderson.
I wanted to reflect on questions that I’ve been asked from dozens of homeowners over the past few years, as well as take a closer look at the questions the authors proposed. They asked a question that I’ve heard time and time again. Are new houses being built too tight?Reflecting on older construction techniques, the authors comment “it used to be that builders rarely worried about the air tightness level of the houses they built. Standard construction practices would typically produce a house that generated few if any callback complaints related to air tightness such as moisture on windows or stale odors. By leaving houses with a significant level of air leakage, builders were actually incorporating a passive ventilation system into every house they built. In addition, the lower efficiency natural draft combustion appliances routinely installed in new houses acted like exhaust fans drawing large quantities of outside air into the house. This passive ventilation system was crude, uncontrollable, and created some comfort complaints, but it did satisfy the ventilation needs of most of the houses built more than two decades ago.” In other words, houses were built “loose” enough that they could breath.The question that then presents itself is, “Am I losing money on heating and cooling bills if my house is built loosely?”The authors write “The air tightness of the building envelope is an important key to understanding the performance of any new house. Uncontrolled air leakage can result in high fuel bills, failure of building components, and increased builder callbacks. As a result, more and more time is being spent by the building trades sealing up new houses in an effort to reduce problems associated with air leakage. Yet at the same time, most builders are continuing to rely on uncontrolled air leakage through holes and cracks in the building envelope to provide adequate ventilation for the occupants.”What is making newer houses so “tight?”The authors state that “over the past 20 years, building practices have changed. The advent of the 1973 oil crisis created the first large demand for more energy efficient houses. Increasing insulation levels was the first response to this new energy conscious market. As the cost of energy has continued to increase, other industry responses developed as well. Most notably, building products and construction practices have been developed and adopted which reduce the overall size of air leaks in the building envelope. In fact, many builders are now building much tighter houses without even realizing it. Walk down any new development under construction and it is common to see the use of housewraps, tight fitting exterior sheathings, vapor barriers, and untold caulks, foams and sealants. While 10 years ago, many of these air tightening products where used by only a few custom builders, they are now an integral part of standard new construction practice. Much detail and time are now spent installing continuous vapor barriers, sealing penetrations in the exterior envelope with specially designed foam, and adding gaskets at outlets and plumbing chases.” I would agree, and add that many building codes are being updated to match some of these practices. Additionally, consider these other comments, “In cold climates a better understanding that attic moisture and ice dams problems are caused by warm air leaking into attic spaces has led builders to do a better job sealing attic penetrations. New higher efficiency combustion appliances being installed use much less air for combustion and as a result significantly reduce the amount of outside air being drawn into the house. Add to this the new tighter window technologies and it is no wonder why the average house being built today is significantly tighter than its counterpart of 20 or 30 years ago.” I also agree.
But what about all of the information in newspapers, magazines and on the internet warning about problems with air quality, odors, mold, and mildew, etc.? Unchecked, a tightly sealed house can present a flurry of problems, such as range hoods and clothes dryers creating negative pressures in houses large enough to backdraft furnaces, water heaters or fireplaces. The concern then becomes that this can introduce carbon monoxide and other deadly gases directly into the house. Stoves and ranges can also present a problem. The author states “While not all of the thousands of carbon monoxide poisonings each year can be attributed to tight buildings, it is clear that tight houses are increasingly susceptible to this problem.”
Final Thoughts: The authors present a solid case that relying on passive ventilation is not recommended, and that builders and homeowners should have their designs put to the test, the blower door test that is. (see http://www.energysavers.gov/your_home/energy_audits/index.cfm/mytopic=11190 )I agree with that if ventilation is properly planned and accounted for, that we can continue to find ways to tighten up houses, but within reason. I think that there is a point of no return when it comes to investing time,energy and money in siding, windows, roofing and other parts of a building’s envelope. Properly planned, a good balance can be achieved. Other Recommendations from the cited article: for New Construction
- Have a blower door test done on one of your typical houses
- Avoid natural-draft combustion appliances
- Warn your customers about the dangers of open fireplaces.
- Try to minimize sources of indoor pollutants
Leave a ReplyWant to join the discussion?
Feel free to contribute!