If you have a well sealed house like the Brooklyn Green Show House you need to add an air ventilator.

The best kind is one that recoups the heat and cold that leaves the house. That would be called a Heat Recovery Ventilator (HRV).

But another thing is humidity. You want it to stay within healthy levels in the house. An energy recovery ventilator (ERV) can monitor the humidity levels as well as recover heat and cold.

Even though technically ERV’s have been around for about 30 years, they are not common for small residential use and it is still hard to get good information on which one to buy.

I have looked around and found a handful. I share my research here:

Paul is a leading ERV from Germany. They have a heat recovery technique where air flows over 4 surfaces instead of two, thus making it much more effective.

American Aldes has a “vent zone” system where you can control different zones of the house, thus reducing the need for a large fan and thus saving energy.

Conservation Technology uses an exhaust only system and they claim this is more energy efficient. They combine it with occupant sensing technology so that the fan can regulate its speed based on the need.

Renew Air claims to have the most energy efficient fans in the US. They also boast quiet fans. It seems to be mostly an ERV that you hook up to an existing air circulation system that would handle heating and cooling but you can probably use it separately too.

AirScape is more of a cooling system to replace AC. It is good for running at night to cool down the house. Not really a system to help keep the heat in during the winter so it’s not actually an ERV. But it is a very effective alternative to AC cooling in the summer.

Ultimate Air claims to have one of the highest efficiency in the industry.

Lifebreath offers a good ERV.

Aprilaire only recovers 77% of the energy. Not great.

My favorites are Renew Air and Ultimate Air. I lean towards Ultimate Air because they are really into the Passive House technique of building. We are increasingly building along Passive House standards in our green contractor work on Brooklyn brownstones. It covers a lot of the energy considerations in a green renovation.