Your ventilation system is key to indoor quality


By CCHRC Staff

The “Ask a Builder” series is dedicated to answering some of the many questions Fairbanks residents have about building, energy and the many other parts of home life.

Q: I had an energy rating performed on my home, and it said my house does not have enough ventilation air for acceptable indoor air quality. What does that mean and what are my options?

As part of the energy rating, the rater conducts a blower door test to depressurize the house. This test uses a large, calibrated fan to determine how much air is leaking in and out of the house. If this leakage rate falls below a certain range, the energy report will contain a cautionary statement warning the homeowner that the home is too “tight.” This may result in poor indoor air quality unless the building has mechanical ventilation. All homes must be able supply a specific number of air exchanges per hour in order to meet state and national standards for air quality. The required volume of fresh air is determined using a calculation that factors in house size and number of occupants. A tight home can suffer from a variety of ailments, such as moisture build-up and mold growth. Not all air quality issues are this obvious, however. For example, if combustion appliances such as propane ovens aren’t operating properly, or if car exhaust is drawn into the house from an attached garage, then low levels of carbon monoxide can linger in the living quarters for extended periods. These levels are often too low to register on a carbon monoxide detector, but over time can have a negative effect on occupant health. Air quality issues can also arise from off-gassing of building products such as new carpets and solvent-based finishes.

Animal dander, dust mites and chemicals released by household cleaners can also contribute to poor air quality.

Today, most building codes require some form of mechanical ventilation.

This can range from an appropriately-sized exhaust fan operating in conjunction with fresh air inlets installed in the living spaces to a Heat Recovery Ventilation System (HRV).

Regardless of which type of system is used, it must be sized and installed to meet the needs of the home it will be serving.

A healthy, efficient house must perform a balancing act between cost and indoor air quality. This means that the ventilation system has to supply enough fresh air to meet occupant needs, while at the same time minimizing the energy penalties associated with over ventilating.

Q: Who determines building code and how is it changed?

At this point, the most predominant residential code used in the United States is produced by the International Code Council (ICC), although some municipalities opt to use codes from other sources.

The ICC produces the International Residential Code (IRC) which is updated every three years. The city of Fairbanks building officials uses the 2006 IRC book, but will soon be adopting 2009 codes.

Because this is a national code, it does not perfectly meet the needs of every individual region, so it is up to the local jurisdiction to establish appropriate exceptions. For each code cycle, our local Building Code Review and Appeals Commission makes amendments to the IRC in order to adapt it to Fairbanks. This commission is comprised of contractors, engineers, architects, and local code officials. As an example, the Commission has increased the snow load requirements to better reflect conditions in Fairbanks. All the amendments are available at the building department and online on the city of Fairbanks website at Outside the city of Fairbanks, no code is enforced unless the lending agency requires it. However, building codes exists to insure that a minimum standard of occupant health and safety is met. It is worth noting that if a house is not built to meet local codes it can be difficult to sell.

Alaska HomeWise articles promote home awareness for the Cold Climate Housing Research Center (CCHRC). If you have a question, e-mail us at can also call the CCHRC at (907) 457-3454.