What is the Exhaust Ventilation System?

Natural ventilation is the standard ventilation system that allows fresh outdoor air to flow into the house to replace indoor air. Natural ventilation is no longer efficient, especially for homes that are tightly sealed for energy efficiency. Opening windows and doors are no longer regarded as the norm. Therefore, air infiltration has become the principal mode of ventilation for homes.

Natural ventilation is uncontrollable, thus undependable to ventilate the whole house uniformly. Natural ventilation depends on the house’s airtightness, outdoor temperatures and other factors. A tightly sealed house may have insufficient natural ventilation whilst a place with high air infiltration rates is costly to maintain.

Houses or buildings become energy efficient, given concern about the occupants’ health and well-being and low indoor air quality (IAQ). Indoor air quality can be unhealthy and has many adverse effects, including allergies, asthma, cancer, liver and kidney failures.

Mechanical ventilation is the solution for energy-efficient homes to maintain their indoor air quality. There are four basic mechanical whole-house ventilation systems, namely Exhaust, Supply, Balanced and Energy Recovery. The efficient ventilation system for a house depends on the climate and the building structure.

Illustration of Exhaust Ventilation System

Exhaust Ventilation 

In summary, Exhaust Ventilation is inexpensive and straightforward to install. It works well in the cold climate. It is not suitable for humid climates, relies on random air leakage, may increase heating and cooling costs, requires a mixture of indoor and outdoor air to avoid drafts in cold weather, and can draw pollutants into living space back-drafting in combustion appliances. 

What is the Exhaust Ventilation System?

How it works – It works by depressurizing the house. It exhausts air from the make while air infiltrates through leaks in the building shell and intentional, passive vents. It works well in cold climates, as in warm, humid climates, and the depressurizing can draw moist air into the building wall cavities where it may condense and cause moisture damage.

It is inexpensive and straightforward to install. It consists of a single fan connected to a central location in the house. For better design, the fan is connected to ducts from several rooms where pollutants are generated, presumably the bathroom/s. Adjustable, passive vents through windows or walls can be installed in other rooms to flow fresh air compared to total dependence on leaks in the building envelope. However, passive vents require more considerable pressure differences than those using ventilation fans to work efficiently.

A simple approach would be the function of spot ventilation exhaust fans installed in the bathroom and operate continuously.

Primary Concerns of Exhaust Ventilation

The system may not only draw fresh air into the house but may remove pollutants including:-

  • Radon and moulds
  • Dust 
  • Fumes from the attached garage
  • Flue gases from a fireplace or fossil-fuel-fired water heater and furnace

The pollutants are more of concerns during bath fans’ operations, range fans, and clothes dryers with the Exhaust Ventilation system’s subsequent procedures, which will also depressurize the house. It can also contribute to higher heating, and cooling cost as the system does not remove moisture from the air before it enters the house.