“Why do I need ventilation in my home?” is a question homeowners may ask. The reasons for needing fresh air becomes clearer, once we consider what pollutants might be in the air in homes. Most homes have the potential for VOCs (volatile organic compounds) from cleaning agents, carbon dioxide from occupants (including pets), and many other gases or biological pollutants. The United States Department of Energy produced an “Energy Saver” document that explains the benefits of installing Whole-House Ventilation systems, Whole-House Ventilation | Department of Energy. Let's compare the pros and cons of each of the four system types - Exhaust Ventilation, Supply Ventilation, Balanced Ventilation and ERVs (Energy or Enthalpy Recovery Ventilator).
Exhaust ventilation systems will typically utilize a ducted fan to depressurize the home. Drawing the stale air out and leaving the home in a negative static pressure. Meaning it will rely on properly sized passive infiltration of fresh outside air into the structure. These work well in colder climates and are simple to install. Though they have many disadvantages, such as: potential to draw pollutants into the living space, increased utility costs, possible back drafting of combustion appliance venting, and they are not suitable for humid climates.
Another type is defined as Supply ventilation systems. These are the opposite of exhaust ventilation systems. This means Supply ventilation will turn many of the cons of Exhaust ventilation into Pros. By drawing fresh outdoor air into the structure, pressurizing the living space, and relying on passive air leakage of the building. Most homes will already have plenty of vents capable of relieving this pressure, such as bath fans, driers, ducted range vents, etc. Some Cons of Supply ventilation are: increased utility costs, may result uncomfortable drafts or humidity concerns in cold climates.
There are also systems called Balanced ventilation. These draw in and expel equal amounts of air. This keeps the home at a neutral static pressure, while still exchanging air in the building. Making this type appropriate for all climates. However, they are more costly to install and may increase utility costs.
Lastly is the most preferred ventilation system called ERV (Energy or Enthalpy Recovery Ventilator). Having a high initial cost of installation and maintenance is nominal in comparison to the benefits of having this system in your home. These devices move two separate air streams through a silicate coated heat exchanger. Allowing heat and moisture to transfer from one air stream to the other, without mixing the air molecules. This will provide superior air exchange and maintain the best comfort level without increasing utility consumption. Capable of recovering about 70% to 80% of energy exiting the air. Operational costs may not be as cost effective in milder climates. But they are the recommended ventilation type in any climate where humidity is a factor.
IAQ is an important factor to the wellbeing of your family and home. There are many methods and products available to provide a healthier environment.