Choosing Your Whole House Ventilation System

Copyright (c) 2015 Matt Reardon

For your home to be energy-efficient, it requires a good mechanical ventilation system to maintain the quality of your indoor air. The Journal of Light Construction in its 2014 issue has pointed out that beyond just picking a system, there are 3 critical steps towards getting a ventilation system which works efficiently. These are: design properly, install well and commissioning.

There are 4 basic whole house ventilation systems from which you could select the one that best suits your requirements. Below we look at each of these mechanical ventilation systems.

1. Exhaust Ventilation Systems

These are the systems that are most suitable for cold climates. In warmer and humid summer climates, depressurization could draw in moist air into your building wall cavities, where it could condense and lead to moisture damage.

These systems are rather simple and economical in their installation. Typically, a system will comprise of a single fan that is connected to a single centrally located exhaust point within your house. A better design would be to connect your fan to ducts coming from a number of rooms which generate the most pollutants such as kitchens and bathrooms. All exhaust systems in Australia must be installed in accordance with Australian Standard AS 1668.2 of 2002.

A major apprehension with these systems is that together with fresh air, they could also draw in a number of harmful pollutants such as:

- Radon and moulds from your crawlspace

- Dust from the attic

- Fumes from a nearby garage

- Flue gases from your fireplace, furnace or water heater.

2. Supply Ventilation Systems

These systems utilize a fan in pressurizing your home. This will force outside air inside your house while air leaks out through any vents within the house shell, bathroom and fan ducts. They are also relatively inexpensive and simple to install.

Supply ventilation systems are best for climates that are hot or mixed. In cold climates, they could potentially lead to moisture issues because they pressurize your house. They don't reduce or get rid of moisture from the incoming air. Consequently, they could contribute to higher costs for cooling and heating.

3. Balanced Ventilation Systems

A balanced ventilation system typically has 2 fans and 2 duct systems. Two will bring in fresh air while two take out the stale one. It in addition will also exhaust air from any of your rooms where pollutants and moisture are often generated in larger volumes such as your kitchen, bathrooms or the laundry room. These systems are suitable for all types of climates.

4. Energy Recovery Ventilation Systems

Energy recovery ventilation systems (ERVs) present a controlled method of ventilating your home whilst at the same time minimizing loss of energy. ERVs are usually more costly in their installation compared to the other systems. In addition, when operating in extremely colder climates, they need devices to assist them from freezing and from the formation of frost. They also require more maintenance compared to other ventilation systems.

The Journal of the Air & Waste Management Association vol. 58 Issue 11 of 2008 notes that majority of ERVs can recover approximately between 70% and 80% of the energy contained in your exiting air and then deliver that same level of energy to the air that is incoming. They are however, most cost-effective in extreme summer or winter climates and in locations where the costs of fuel are high.


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Matt Reardon works in the engineering section of MouldBuster. He is fully certified to offer you genuine and sound advice on home systems. MouldBuster is fully registered with the governing bodies. Visit http://mouldbuster.com.au/whole-house-ventilation/ for more info about their services.