Balancing act: energy recovery systems

The idea of having fresh, dry air circulating throughout the home is a simple one. In days gone by, that was achieved simply by opening windows and doors and allowing air to pass through the house. That’s no longer a reality for many, especially those who live in terraced housing or apartments.

Even for those who live in standalone houses, the reality of opening windows and doors throughout the day is generally not possible with houses often locked and shut during work hours. Without the right – or any – ventilation system, that means a buildup of moisture and stale air.
In turn, this puts more pressure on heating devices like heat pumps that work harder and cost more to operate because they are heating moist air rather than fresh, dry air.

“It’s as a result of these issues that we are seeing people turning more and more towards whole-home ventilation and energy recovery systems,” HomeTech’s Manny Boyack says. “Our energy recovery system is a whole-home ventilation system that is known as a balanced system because it equally extracts moist, stale air while inputting fresh, dry air into the home.”

The system reduces the home’s energy load because it removes moisture in the air, allowing heating appliances to work less to maintain the desired temperature.

“One of the key benefits of this system, aside from the moisture control, is the system’s ability to temper the incoming air with that which is being extracted,” Manny says. “When the air passes out through a heat exchange unit in the roof cavity, up to 80 per cent of the heat in that air that is being expelled is recovered, and that heat is then tempering the air that is being drawn into the home.”

That means, for example, if the air leaving the house was sitting at a temperature of 20 degrees, the incoming air would be tempered up to a temperature of 16 degrees as it passes through the heat exchange and enters the home, depending on the outside air temperature.

“So while heating appliances are already working less because the air in the home is fresh and dry, it’s also entering at up to 80 per cent of the temperature the outgoing air had been heated to, so the loads are significantly reduced in two ways.”

While this is a central benefit of the energy recovery system, the system itself is not classed as a heating system; it is a ventilating, energy recovery system.

“It is a requirement of the Building Code that all homes have certain levels of fresh air,” Manny says. “But that’s getting harder to achieve with double and triple glazing, insulation and better sealing of buildings. It’s also an issue in higher density housing and in areas where homes are on main roads or in other noisy areas such as near an airport and the occupants may not want to open windows or doors to let in fresh air. This type of system is a way to allow for fresh air without the need to open up the home to the elements.”

There are two main types of whole home ventilation systems: balanced systems, such as the energy recovery system, and positive pressure systems. “Positive pressure systems work by forcing air from the roof cavity through a filter and down into the house. With older houses there are generally draughts and so this can work quite well because there are ways for the moisture to escape. In new houses, though, this doesn’t always work because they are sealed much better than older homes and so there is nowhere for moisture to escape, the result of which can be potentially that moisture is forced into the wall linings which could create issues with mildew and condensation that can be negative for human health and cause issues with the house itself.”

Balanced systems, in comparison, work on a reticulated system where air and moisture is expelled simultaneously with fresh air entering the house, which allows these types of systems to operate efficiently in both old and new homes.

Get in touch with Hometech on ArchiPro here to find out more about balancing the air in your home.