There are a number of reasons why ventilation is much more important today, than it was a couple of centuries ago. Most significantly, a hundred years ago houses were, if truth be told, extremely leaky. Typically they lacked insulation in their walls, such that fresh air could easily penetrate via all the numerous cracks, holes and gaps in the building structure.
However, today, according to the Australian Bureau of Statistics (ABS) 2012 Australian households Survey, the greater portion of Australian buildings would greatly benefit from enhanced air sealing. The AHS found out that air leakage accounts for between 15 and 25 per cent of all winter heat lost in buildings. It also contributes to a considerable loss of coolness during the summer in houses where air conditioners are in use.
The National Building Regulations (Building Code of Australia) have since made tremendous improvements towards enhancing thermal comfort levels in Australia since 2003. The BCA has generally led to huge improvement towards the level of new homes sealing hence promoting the wider usage of ventilation systems.
Currently, if you want to install some form of home ventilation, you’ll generally have to choose from about 4 broad categories. These include the following:
1. Exhaust Only Type of Mechanical Ventilation
This is a rather common ventilation strategy in which a number of small exhaust fans, usually placed in your bathrooms and kitchens, work to exhaust generated excess moisture and stale air. The mechanism creates some negative pressure in your house that then pulls in fresh air from the outside. The advantage is its simplicity and very low cost. The drawback is that the same negative pressure could pull in other unwanted gases into your home.
2. Supply Only Type of Mechanical Ventilation
With this system, a fan conveys fresh air while the stale and moisture laden air escapes via air-leakage sites or cracks in your house. A supply-only ventilation arrangement pressurizes your house, which could be an excellent thing in keeping other contaminants from entering into the house. However, it runs the risk forcing the air that is moisture-laden into your ceiling cavities and wall where moisture and condensation problems could occur.
3. Balanced Ventilation
Improved ventilation is offered to your home through a balanced system by which separate fans propel both exhaust and inlet airflow. This mechanism allows you to control and manage where the fresh air is coming from, where it gets delivered and from which locations exhaust air gets drawn.
4. Heat Recovery Ventilation (HRV)
If you have separate fans introducing fresh air and exhausting bad air, it would make lots of sense in locating the fans alongside each other and introduce a heat exchanger. This way, the outgoing house air will impact on the incoming air. This is what is known as Heat Recovery Ventilation or simply HRV and very suited for colder climates.
A somewhat different version of the HRV, referred to as the Energy Recovery Ventilator or ERV works in a similar fashion but with added benefits. It also transfers or maintains moisture as heat hence keeping a suitable balance of humidity in the house, depending on the season.