Balanced ventilation systems, if properly designed and installed, neither pressurize nor depressurize a house. Rather, they introduce and exhaust approximately equal quantities of fresh outside air and polluted inside air, respectively. A balanced ventilation system usually has two fans and two duct systems. It facilitates good distribution of fresh air by placing supply and exhaust vents in appropriate places.

A typical balanced ventilation system is designed to supply fresh air to bedrooms and common rooms where people spend the most time. It also exhausts air from rooms where moisture and pollutants are most often generated, such as the kitchen, bathrooms, and the laundry room.

Like both supply and exhaust systems, balanced ventilation systems do not temper or remove moisture from the air before it enters the house.

They do, however, use filters to remove dust and pollen from outside air before introducing it into the house.

Also, like supply ventilation systems, outdoor air may need to be mixed with indoor air before delivery to avoid cold air drafts in the winter. This may contribute to higher heating and cooling costs.

Balanced ventilation systems are appropriate for all climates; however, because they require two duct and fan systems, they are usually more expensive to install and operate than supply or exhaust systems.

Information couretesy of EERE