GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Most efficient HRV/ERV product for small airtight space, all seasons?

EfficiencyDude | Posted in Green Products and Materials on

Hi, I’m building a mobile office using a heavily-insulated, airtight 20-foot shipping container. All heating/cooling is via a single heat pump powered by batteries and 2000 watts of solar panels on the roof; this will have no windows. It will be used in New England, so cold winters and hot summers.

I wanted to know what the most efficient heat recovery ventilation would be for such a small space, that I can actually buy in the US.

So far the best candidates I’ve found are:

– Zehnder Novus 300 HRV (claims certified 93% efficiency by Passive House Institute)

– TwinFresh Comfo (claims sensible efficiency of 91%, no PHI cert that I can find, but affordable price and smaller footprint, plus it is a 12v DC system so more compatible with my solar than the Zehner which is AC)

Are there any other products that meet or exceed the efficiencies of these? In my situation, would a central HRV like the Zehnder be better, or a pair of the TwinFresh synchronized for intake/outtake? Thanks for the help.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. GBA Editor
    Martin Holladay | | #1

    Efficiency Dude,
    Lunos fans claim a heat recovery efficiency of 90.6%. Note that there are various ways to determine HRV efficiency, so you might want to delve a little deeper into these claims if the efficiency matters to you.

  2. GBA Editor
    Martin Holladay | | #2

    Efficiency Dude,
    I hope you have a backup plan for space heat. During the winter in New England, it's easy to get three weeks of cloudy weather. I don't know what kind of battery you think is going to power a heat pump through three cloudy weeks in December.

    Certainly, 2 kilowatts of PV on the roof will be close to useless from November 1 to February 10.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |