

Tightening an old house or building a tight new one means that you can’t leave ventilation to random leaks anymore. You have to control it.
Whole-house mechanical ventilation is the intentional exchange of indoor air with fresh outdoor air at a controlled rate using fans. Its purpose is to improve indoor air quality. Historically, mechanical ventilation was restricted to local-exhaust (kitchen and bath exhaust fans) for spot control of moisture and odors. Houses normally had enough natural ventilation, through leaky building enclosures, that ventilation was not necessary.
Houses have become considerably tighter during the past 15-20 years as a result of changing codes, energy efficiency programs and an overall desire to reduce energy use.
Benefits of whole-house mechanical ventilation include:
Different Types Of Mechanical Ventilation
There are three types of whole-house mechanical ventilation systems: exhaust-only, supply-only, and balanced. Each system uses a combination of fans, ducting, dampers and controls, and they each have different pros, cons, and costs accompanying them.
Exhaust-Only Ventilation
Exhaust-only ventilation tends to consist of a fan, commonly a bath fan, exhausting indoor air. Outdoor makeup air is drawn into the house through leaks in the building’s enclosure.
Pros/cons/cost:
Supply-Only Ventilation
Supply-only ventilation consists of a fan drawing outdoor air into the house. Indoor air escapes through the building enclosure and exhaust fan ducts.
Supply-only can be a dedicated system, or more commonly a central-fan integrated (CFI) system. With a CFI system, outdoor air is ducted to the return plenum of an HVAC air handler that draws in and distributes the outdoor air.
Pros/cons/cost:
Balanced Ventilation
Balanced ventilation systems are a combination of exhaust and supply methods roughly providing equal indoor exhaust and outdoor supply air flows (e.g. an exhaust fan combined with a supply fan or passive inlet vents).
A balanced system could include a heat recovery ventilator (HRV) or an energy recovery ventilator (ERV).
Pros/cons/cost:
There are pros and cons to each type of mechanical ventilation but one type may work better for your home than the other two. By consulting a certified professional, you can better your home’s air quality with the right mechanical ventilation system. All of these systems have air filters that have to be replaced. Make sure you do it at exactly the right time with a FILTERSCAN WiFi Air Filter Monitor from CleanAlert.