The ABCs of IAQ and Ventilation

John P. Lapotaire, CIEC

By The Home Ventilating Institute (HVI)

There are two primary reasons for ventilating houses: 1) to provide the necessary fresh air for the occupants to breathe and 2) to dilute indoor air pollutants and excess moisture. Complaints of stuffiness, unpleasant odors, and illness are common in houses that contain too little fresh air. Outdoor air pollution is bad enough, but we are now learning that indoor air pollution is almost always considerably worse—and this polluted air can make us sick.

To feel comfortable and healthy, people simply need clean, fresh air. Mechanical ventilation systems are specifically designed to exchange the air in a house—as well as circulate it.

A ventilation system should be as reliable and predictable as our own lungs. Houses without mechanical ventilation systems get their air quite by chance—the air moving into and out of them is totally uncontrolled. For example, air may infiltrate indoors only when the wind is blowing. We deserve to have control over the air we breathe, we deserve more than “ventilation-by-chance,” we deserve “ventilation-on-purpose.”

Without a doubt, each and every one of us could benefit from a mechanical ventilation system in our home. Ventilation is not a mysterious high-tech process; it is very simple once you understand the basics. Ventilation should be as important as air conditioning, electric lighting, closets, kitchen cabinets, and indoor plumbing which we take for granted as necessary components of our homes. The Home Ventilating Institute (HVI) recommends selecting equipment bearing the HVI-Certified Label which provides homeowners assurance that the products will perform as advertised.

Mechanical ventilation is generally regarded as being more important in today’s tighter houses than it was in the loosely built houses of the last century. Knowledge about how houses work has evolved considerably in the building-science community over the past few years. We now know that a house is more than the sum of its parts—it is a dynamic, ever-changing system.

When a house is viewed as a system, aspects of moisture control, infiltration, safe chimney operation, pollutant sources, duct leakage, pressure imbalances, and ventilation all become interconnected. Thus, we are concerned not only with ventilation per se, but also the various side issues that affect indoor air quality.

Indoor air pollution is responsible for symptoms ranging from sinus congestion to cancer, from depression to immune-system damage. It isn’t unusual for everyday symptoms such as headache, drowsiness, runny nose, lethargy and inability to concentrate to be related to poor indoor air quality.Sources of pollutants

• Gaseous pollutants – Volatile organic compounds (VOCs) are gases that are emitted, or outgassed, from a wide variety of modern materials; combustion gases from fireplaces or gas ranges; people and animals also release carbon dioxide (CO2) and other by-products of metabolism.• Metals – Lead, mercury, or arsenic can chalk off from paint or treated lumber and be tracked indoors.• Minerals – Minerals, such as calcium can also become air pollutants. Their particle size is so small that they can be inhaled deeply into the lungs.• Radiation – Problems occur when radon seeps into houses and builds up to dangerous concentrations.• Biological pollutants – Dust mites, mold, and mildew are irritating health hazards.• Pesticides – When used indoors, pesticides can be serious indoor air pollutants.• Smoking – The most effective way of reducing the danger associated with smoking is to ban smoking indoors.

While a human body is capable of tolerating a certain amount of contaminated air, evidence from a variety of sources tells us that we are being exposed to more pollution than our metabolism can adequately process—especially when we are indoors—and it is making us sick. But there is no reason for this trend to continue. After all, a variety of strategies can be used to build houses with minimal indoor air pollution. These low-pollution “healthy houses” have one thing in common: they all have mechanical ventilation systems.

The Home Ventilating Institute recommends the exclusive use of products which are HVI-Certified. The proven performance provided by HVI Certification is essential when selecting home ventilation products to control the air you breathe.

• John P. Lapotaire, CIEC• Certified Indoor Environmental Consultant• Microshield Environmental Services, LLC• www.Microshield-ES.com