23 November 2017
Heard about free heating and cooling you can get from a home ventilation system? Sounds like a good deal, right?
There are a number of home ventilation products on the market that have become popular in recent years. Probably the best known brand is HRV, but there are many more.
These types of home ventilation systems are essentially just a fan installed in your ceiling space, with a duct connected to one of the rooms into your house. The fan draws air from your ceiling space and pumps it into your house.
This has a couple of effects. Firstly, it creates a higher air pressure in your house than the outdoor air pressure. This prevents moist air from outside coming in through your windows and doors, which keeps your house dry and prevents mould forming. This is sometimes known as an overpressure system.
The second effect is more widely-advertised. Many suppliers claim that their products provide free heating in winter and free cooling in summer. Their reasoning is that the ceiling space in your house stays warmer than your house in winter, and cooler than your living areas in summer. So by transferring air from the ceiling cavity to your house you can take advantage of the free heating and cooling.
A study by the University of Otago in 2010 showed that there’s no significant heating or cooling available from these types of systems. In fact most of the time, pumping the ceiling air into the room moves the temperature the wrong way – ie, makes it colder when you want it to be warmer.
So while there may be some value in the ventilation benefits of these types of systems, they don’t provide any heating or cooling.
It should be noted that there are other, more complex ventilation systems on the market. But for all intents and purposes, an ventilation system provides ventilation – if you want heating or cooling, you need to install heating or cooling equipment!