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Weatherization is key to a healthy home

  • Author: Colin Craven
  • Updated: September 29, 2016
  • Published October 8, 2012

Sealing your Alaskan home against the elements ensures that you and your family are comfortable and safe. It is also an important step in making your home energy efficient and ensuring good indoor air quality. A recent article suggested a connection between home weatherization and unsafe indoor air quality. There are several assumptions made by the author, Craig Medred, that may leave readers with mistaken impressions regarding the potential benefits and drawbacks to weatherization, and I thank Alaska Dispatch for allowing me the opportunity to provide clarification.

As the co-chair of Alaska Craftsman Home Program's Technical Advisory Committee, I serve Alaskans by providing the best available information on building science and best practices. I believe it is important to assure readers that weatherization done right is not only safe, but is also proven to benefit the home and its occupants.

A weatherized home is a healthy home

Craig Medred cites a recent study published in the journal Environmental Health Perspectives that connects elevated levels of carbon dioxide (CO2) with reduced levels of cognitive function. Simply put, breathing air with more CO2 made the study volunteers less effective and efficient at office work tasks. The study is compelling, and the authors discussed some important potential links to indoor environments with high occupancies (such as schools and office buildings).

Medred incorrectly assumes that the new study shows weatherization to be risky. In fact, the headline directly questions whether weatherization could pose risks to human health. This is going far beyond anything stated in the new study. He leaves one with the impression that weatherization can only raise CO2 levels in the home, which is not an assumption that is supported in his cited reference material.

On one point Medred and I are in absolute agreement: Adequate ventilation is an essential component of a healthy home environment. However, Medred assumes that ventilation is not addressed when upgrading a home for energy efficiency. In fact, weatherization and retrofit professionals are trained to test for airflow, and to assess if additional ventilation is required in order to ensure that a home is healthy and comfortable for the occupants.

Build it tight and ventilate right

While it may seem counter-intuitive at first, healthy air quality can only be consistently maintained by controlling air flow throughout the home. It is very difficult to adequately control moisture flow and ensure the removal of indoor air pollutants if a home is very leaky. Additionally, leaky homes can also be uncomfortable and inefficient to heat. A study of homes in Canada found that leakier homes had higher levels of biological contaminants resulting from excess moisture. Experience from radon mitigation in Alaska compiled by the Cooperative Extension Service confirms that air sealing is a crucial first step. These are just a few examples of how a leaky house makes it harder to provide good indoor air quality. This is true whether the concern is mold, radon, CO2 or any number of possible sources of indoor air contamination. The path forward is to control air leakage, specifically address ventilation, and not leave it to luck that air leakage will provide good indoor air quality.

Weatherization is the right choice for Alaskan homes

Medred is concerned that weatherized homes may be sealed too tightly, creating a situation where pollutants (including CO2) build up to create a potentially harmful environment. This is a legitimate concern that building and weatherization professionals take seriously.

My colleagues and I at Alaska Craftsman Home Program believe that it is to the detriment of Alaskans to portray weatherization as unsafe or unhealthy. As with any home improvement, one must ensure that the job is done right, and that includes hiring a reputable building professional familiar with healthy ventilation standards. Proper weatherization improves indoor air quality, lowers energy bills, and makes Alaska homes more comfortable year-round.

Colin Craven is building science research director for the Cold Climate Housing Research Center. Headquartered in Fairbanks, the CCHRC is an industry-based, nonprofit corporation created to facilitate the development, use, and testing of energy-efficient, durable, healthy, and cost-effective building technologies.

The views expressed above are the writer's own and are not necessarily endorsed by Alaska Dispatch. Alaska Dispatch welcomes a broad range of viewpoints. To submit a piece for consideration, e-mail commentary(at)

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