Home Ventilation Options
It is important to provide adequate ventilation in a home. Ventilation helps remove indoor air pollutants, moisture and odors. Energy-efficient homes focus on making a home airtight to prevent the loss of energy through cracks and by properly sealing all spaces where air, and therefore energy, can escape a home. The more tightly sealed your home is, however, the more important it is to consider other ventilation strategies.
All homes need an exchange of indoor and outdoor air in order to maintain a healthy home. Proper ventilation reduces contaminants such as formaldehyde, VOCs (volatile organic compounds), and radon that can accumulate in poorly ventilated homes and can lead to health problems. Ventilation also removes excess moisture in a home, which can otherwise lead to high humidity levels and the growth of mold or even possible structural damage. Lingering odors in a home are unpleasant and can be easily removed with proper ventilation.
Types of Home Ventilation
The American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) recommends that a home should be ventilated at a rate of the greater of 0.35 air changes per hour or 15 cubic feet per person per minute.
There are three basic ways to provide proper ventilation in your home. These are natural ventilation, spot ventilation, and whole house ventilation. Below is an explanation about each type of ventilation strategy.
Natural ventilation occurs when air infiltrates through cracks or small holes in a home, or even by opening windows or doors. It results from uncontrolled air movement between the inside and outside of a home. Natural ventilation used to be the most common ventilation method in homes, but is not usually as effective in today's homes because many homes are sealed more tightly to provide energy efficiency and many people don't open windows and doors as often because they have centralized heating and air conditioning systems.
The problem with natural ventilation is that it is unpredictable and uncontrollable. It depends on many factors, such as the temperatures indoors and out, the amount of wind, and how tightly a home is sealed against air infiltration. There is a tradeoff between the amount of ventilation received and the energy efficiency of a home. Homes that are tightly sealed enjoy better energy efficiency but may have insufficient levels of air ventilation, while those homes that have enough cracks and holes to provide sufficient natural ventilation are usually not very energy efficient. Also, with natural ventilation, a home is not usually ventilated on a uniform basis. Another problem with natural ventilation is that it often doesn't provide sufficient moisture control.
If natural ventilation doesn't offer enough ventilation in your home to rid it of pollutants and moisture to keep the air healthy, spot ventilation may help in addition to natural ventilation to make your home's air healthier. If both of these methods combined are still not enough, you may need to consider a whole house ventilation strategy.
Spot ventilation can be used to improve the effectiveness of either natural ventilation or whole house ventilation by removing pollutants and moisture in a specific place or at its source. This can be done with devices such as exhaust fans that are placed in kitchens or bathrooms. ASHRAE recommends using exhaust fans for intermittent or continuous ventilation in kitchens and bathrooms, instead of just relying on natural ventilation methods in these rooms.
Whole House Ventilation
A whole house ventilation system is used to provide uniform ventilation throughout a house at a rate that can be controlled to meet various needs. This is a system that is usually considered when it is determined that natural ventilation just isn't enough to keep air quality healthy, even with spot ventilation usage. Whole house ventilation systems utilize fans and duct systems that can either send indoor air outdoors or supply fresh outdoor air into the home, or a combination of both.
There are four types of systems available for whole house ventilation systems. These include exhaust, supply, balanced, and energy recovery ventilation systems. Exhaust systems force indoor air outdoors, while supply systems bring outdoor air indoors. Balanced ventilation systems force air equally into and out of a home, and energy recovery systems transfer heat from that incoming or outgoing air in an effort to minimize the amount of energy that otherwise would be lost.
It is important in today's more energy efficient homes to make sure that there is adequate ventilation in place to keep indoor air healthy, to remove pollutants, and to reduce moisture and odors. When natural ventilation is not enough to do the job effectively, spot ventilation solutions can help. When a home needs more than natural and spot ventilation, whole house ventilation systems can be employed to provide the transfer of air needed to keep indoor air quality high.