This is an open source Energy Recovery Ventilator. It's a machine which gives you fresh air without the obvious and prohibitive heating problems associated with opening a window when it is very hot or very cold out. It prevents the escape of heat during winter, and the intrusion of heat during summer, automatically.

For a discussion on what an ERV is, the importance and value of such a machine, see the website.

This unit gets ~28 cubic feet per minute on the maximum setting, measured with an anemometer.

It is a bit noisy on the maximum setting, about 50 dBa, however on more moderate settings it is quite quiet. At 20 CFM, it's like the fan on a typical desktop computer, in terms of sound. It's quieter than my computer right now, at 20 cfm. If you put it to the lower range of the power dial (the adjustment is continous), then it's very quiet, but there is still the whoosh of air and a tiny bit of motor hum. However, any ordinary fan or appliance will be louder, so you are not likely to notice or mind.

This unit has been tested and the specs are the same as those listed on the website in the specs section, about 88% sensible efficiency, and between 40 to 80 percent latent efficiency, which varies substantially depending on conditions. The larger the temperature differential, the higher the latent efficiency gets.

Why did you make it?

This is the last of the prototypes, the most developed of them. I made it as part of developing the design and production methodology of the OpenERV. However I also made it with the intention that it will have value for many years, indeed decades, in service, as an actual practical money and energy saving unit.

What makes it special?

It is a genuine energy and money saving appliance, manufactured in an "modern artisan", grassroots kind of way. It has no planned obsolescence built in, very low embodied energy and relatively low environmental impact during it's production.

It is the only option on the marketplace for a low cost unit that goes in the window.

It comes with a 60 day satisfaction guarantee, and a 1 year warranty. However, this is a beta unit, so you have to be careful with it, and there is the potential for issues, just know that they will be rectified or your money refunded if they do arise; I stand behind my work.