Fresh Air Systems and Industry Misconceptions
Fresh air systems are growing in popularity. They are also known as air to air heat exchangers. They entered the mainstream building community in the early 1990s. There are two basic methods: the Heat Recovery Ventilator (HRV), and the Energy Recovery Ventilator (ERV). Both of these systems bring in a controlled, pre-determined amount of fresh air from the outdoors. It will also transfer its heating or cooling energy into the incoming fresh air (obviously when it’s freezing outside you don’t want to bring in that cold air into the home). The ERV unit takes it one more step and actually transfers the indoor humidity values into the incoming air from outdoors. Obviously they are not 100% efficient, but if the home is too tight, the fresh air systems are a must (short of opening windows that is).
There are less sophisticated ways to introduce fresh air into a building, such as ducting an outdoor air duct to the return of the system. This is not an ineffective method, but it does have some drawbacks.
In has been widely advertised by filter manufacturers that indoor air is usually less healthy than outdoor air. Here are some facts by some major entities:
In a survey conducted in April 2002, 50% of people surveyed were not aware that poor indoor air quality is one of the top five most urgent environmental risks to public health. American Lung Association
If too little outdoor air enters a home, pollutants can sometimes accumulate to levels that can pose health and comfort problems. US Environmental Protection Agency
Proper ventilation will always make a positive contribution to indoor air quality aiding in the control of contaminants including moisture and mold. Home Ventilating Institute
Indoor air quality is important to human health because we spend over 80% of our time indoors. Tight insulation, too much humidity and other factors can lead to unhealthy air in your home or workplace, causing a number of health problems. Health Canada
Improving ventilation and airflow is basic to air quality, especially if your home is new or recently remodeled. Mayo Clinic
If the house is tight, that is it doesn’t naturally allow outside air to infiltrate, the indoor air can certainly suffer. Where tremendous misconception comes to life is this: Many people truly believe they live in a tight home, but diagnostic equipment will often times dictate otherwise. Do you see the challenge here? If the house is already breathing in its own, why in the world would you want to bring in even more air that must also be heated/humidified or cooled/dehumidified? It makes no sense, but the marketing companies fail to mention this because their goal is to sell clean air products. Most HVAC contractors (less than 1%) do not own equipment to determine the exact level of infiltration, so they go along with what the manufacturers tell them, which is simply questionable at best. The teachings sound logical, but the realities often times defy their clever marketing tactics.
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