Improving Indoor Air Quality

Since the 1970s, when we started building tighter energy-efficient homes, the level of
indoor air pollutants has steadily increased.

Why? Contaminated air which once escaped through cracks around windows and doors is now trapped inside with you and your family.

Today’s energy efficient construction methods make homes so tight that mechanical ventilation is needed to remove contaminants which cause mold, mildew or poor air quality. An energy saving Heat Recovery or Energy Recovery Ventilator is an ideal choice to bring a continuous supply of fresh, filtered air into your home while expelling stale air.

Did You Know?  Everyday Activities add to Indoor Air Pollution

Studies have found that simple things like mopping the kitchen floor, taking a shower, doing the laundry or just breathing can generate enough moisture in your home to raise the relative humidity to an unhealthy level. Increased humidity and moisture inside your home can lead to severe structural damage that you can’t see until it’s too late. Increased moisture levels can also dramatically affect your family’s health due to increased mold and mildew.

Heat Recovery and Energy Recovery Ventilators

Heat Recovery and Energy Recovery Ventilators are the next step in creating a clean, healthy environment for your family.

What Are HRVs and ERVs?

To understand these products and their functions, here are a few things to remember.

Heat Recovery Ventilators (HRVs) are recommended for colder areas of the country that have longer heating seasons as well as drier desert areas of the South.

Energy Recovery Ventilators (ERVs) are designed for warmer, humid climates with longer cooling seasons.

Over a period of time, older homes began to sport new, tight windows and doors, insulation and vapor-barrier improvements, modern siding, and caulk for every crack through which air might pass. New homes left the drawing board designed to be tight, and builders became familiar with the new materials and skills needed to meet market demand and updated regulations. Homes were finally becoming thermally efficient. What some began to wonder, though, was whether they were livable.

It turns out that those heat-robbing drafts had a role in the ecosystem of the home—they provided fresh air to breathe. Without realizing it, builders before the energy crisis had been installing an effective ventilation system. If you could afford the heating bills, it worked.

How Do They Work?


Heat Recovery Ventilators (HRVs)
An HRV is designed to bring a continuous supply of fresh air into a home while exhausting an equal amount of contaminated air. HRVs use what is called a “sensible” heat recovery core. This special aluminum core transfers heat from the exhaust air stream to the incoming air stream. Fresh incoming air is tempered by the heat that is transferred from the outgoing air so you save on energy costs.

Energy Recovery Ventilators (ERVs)
Energy Recovery Ventilators work much like the HRV but it is designed with a different type core. The enthalpic core at the center of the unit transfers heat and moisture from the incoming air to the outgoing air. The air brought into the living area is cooled and the humidity is reduced for maximum comfort. The load on your air conditioner is less and you save on cooling costs.

Depending on the model, HRVs can recover up to 85 percent of the heat in the outgoing airstream, making these ventilators a lot easier on your budget than opening a few windows. And, an HRV contains filters that keep particulates such as pollen or dust from entering the house.

Although an HRV can be effective in the summer months, when it will take heat from incoming fresh air and transfer it to stale air-conditioned exhaust air, it’s most popular in colder climates during the winter.

HRVs are ideal for tight, moisture-prone homes because they replace the humid air with dry, fresh air. In climates with excessive outdoor humidity, an energy recovery ventilator is more suitable. This device is similar to an HRV, but dehumidifies the incoming fresh airstream.

Air-to-air exchangers (heat recovery ventilators and energy recovery ventilators) take the old air out, with its moisture, mold, and gases, and bring new outside air in – without losing warmth and/or coolness.

For information on how these units can help you save energy and lower heating or cooling costs, a Minnesota Heating and Air Conditioning Contractor can answer all of your questions.

Identify Home Pollutants

The air quality of our indoor environments affects our health and often contributes to structural degradation. Learn more


Why Ventilate?

Life inside today’s tight home generates both moisture and pollutants. The moisture comes from cooking, washing, showers and breathing. At excessive levels, moisture condenses on windows and can cause structural deterioration. Areas of excessive moisture are also breeding grounds for mold, mildew, fungi, dust mites and bacteria. You know you have a problem if you find moisture collecting on your windows, or if you notice black spots on walls. These unsightly spots indicate mildew growth. Mold spores and dust easily become airborne and circulate freely throughout the house, possibly causing a range of symptoms and allergic reactions.

In addition to excessive moisture and biological contaminants, appliances that utilize combustion have the potential for allowing gases, including carbon monoxide, and other pollutants to escape into the air. Some common sources may include gas ranges and water heaters, unvented space heaters, leaky chimneys and wood-burning appliances. Even breathing can add to the problem when carbon dioxide reaches excessive levels, creating stale air.

And that’s not all that gets into the air. If your home is new, the very products it’s made of can give off gases that are less than agreeable to your comfort and good health, and in many areas of the country there’s a concern about radon seeping from the ground.