Recovery Ventilation System

Added forced ventilation (energy recovery ventilation or ERV) is another attribute of a passive house, thanks to extreme air-tightness. ERV transfers about 50% of humidity between fresh and stale air streams circulating in your house at any given time. This means less dry indoor air conditions during the winter months. It also helps transfer humid air back to the exterior in the summer easing AC loads. Air volume is based on house envelope size, shape, number of corners, open spaces, etc. If ventilation system design is well calculated and done right, installation becomes a very straight-forward process.

Main ventilation unit, a.k.a. “The Octopus”. It’s made by Ultimate Air and supplies fresh air to the entire first floor and master bedroom. The unit was chosen based on its technical spec, power consumption, price, and stringent passive house compliance rules.

The front of the ventilation unit has two 8-inch duct connectors for air supply (right) and air exhaust (left). Inside is a large fan with a washable six-pie filter drum. it also has a conventional pre-filter at the air inlet.

Efficiency above all: choosing the right ventilation system

There are quite a few brands to choose from nowadays, from world-known companies to niche market manufacturers. The prices vary considerably, therefore no matter what local dealers tell you, prepare to do your own research to estimate your system needs and installation costs. German Zehnder is always on top of every PH consultant’s list. It is a beautifully designed system and “just works” but it came with a forbidden price tag at the time of construction. But Ultimate Air, Lennox, Panasonic, Honeywell, Aprilaire, Fantech, just to name a few, are all worthy choices. I assume they would all work fine for the NOK project given they have enough power to supply airflow for longer runs.

At the end of our research, we zeroed in on Ohio-based Ultimate Air for overall energy efficiency vs value ratio. It features a rotating drum system with washable pie filters and works well for a fairly large house. Keep in mind the system is not whisper-quiet. Some low operational fan noise from the unit is audible, therefore it is advised to install the units away from the bedrooms or recreational areas of the house.

The second ventilation unit is considerably smaller and exchanges air on the second floor. It serves two other bedrooms, the bathroom, and the hallway.

Two pairs of air intake and exhaust with hoods supplied by Ulimate Air.