Example of an HRV installed for a Client in the Roseburg area.

A few articles ago we talked about Indoor Air Quality (IAQ) and how it relates to your ductwork. As we said, IAQ is a multifaceted issue and your ductwork is just one facet. Another is the use of a Heat Recovery Ventilator (HRV).

 Structures today are being built very tight to help with energy costs. Windows are tight, the building envelope well insulated, vapor barriers are used, every crack and seam caulked. The concern now is the lack of ventilation. Not enough outdoor air is being brought in to dilute indoor sources of pollution. Examples of indoor pollution are tobacco, combustion appliance such as ranges and water heaters, fumes from cleaning supplies, off-gassing of building materials, furniture, carpeting etc. Moisture is another concern in a tight structure. Moisture is caused by cooking, washing, showers, breathing etc. These conditions can become a perfect environment for mold, mildew, fungi, dust mites etc. If moisture collects on your windows or black spots appear on your walls, you have a problem. All of the above creates a poor indoor air quality that can have a range of negative health effects.

The American Society of Heating Refrigerating and Air-Conditioning Engineer’s sets the standard at not less than 15 cubic feet per minute per person for residential ventilation. Even an old drafty structure may not be able to achieve this on a still (not windy) day.

Filters will help reduce contaminants but will not help with moisture or gaseous pollutants. Exhaust fans in rooms will help remove moisture but can also create negative pressure in the structure. What is needed is balanced ventilation. What is also needed is a way to warm or cool the outside air as it comes into the structure to reduce energy costs. The way to do all this is to install a Heat Recovery Ventilator (HRV).

A HRV is similar to a balanced ventilation system. The difference is, in winter, the HRV takes the heat from the stale air being removed from the structure and applies it to the fresh cold air coming into the structure through a heat exchange core. The air streams never mix, only the heat is exchanged. Heat is removed from the incoming air in the summer and vented back outside so the interior stays cool. Energy required to heat or cool the outdoor air to a comfortable level is dramatically reduced. For structures with a forced air system, the HRV is typically integrated in the ductwork. In the case of a ductless system, it is separate.

HRV systems now qualify for tax credits. For more information please contact us or go to the Oregon Department of Energy’s website.

IAQ Facts and Statistics

The average American breathes 3,400 gallons of air each day, making ambient air pollution a major environmental problem. – American Lung Association

There are an estimated 42.6 million Americans living with hay fever and/or asthma. 87 percent of American homeowners are not aware that pollution may be worse inside their homes than outdoors. –American Lung Association

Asthma is the most common serious chronic disease of childhood and accounts for 1/3 of all pediatric emergency room visits, more than 200,000 hospitalizations and 14.7 million missed school days annually. – Environmental Protection Agency – Asthma Facts

One out of six people who suffer from allergies do so because of the direct relationship to the fungi and bacteria in air duct systems. – Total Health and Better Health Magazine

Children breathe in 50 percent more air per pound of body weight than adults do. – EPA Website – Indoor Environments Division

Controlling exposure to indoor allergens and environmental tobacco smoke (ETS) could prevent 65 percent of asthma cases among elementary school-age children. By controlling biological contaminants (e.g. dust mites and cat allergens), asthma cases could be reduced by 55 to 60 percent. – American Journal of Respiratory and Critical Care Medicine

Three most important methods of improving indoor air quality are source removal, air cleaning and increased ventilation. – U.S. Environmental Protection Agency

If you would like to learn more about IAQ and would like to talk to us about an HRV for your home or business, please contact us at one of our three offices. 

A diagram of how a HRV works.

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