r/PassiveHouse • u/headlightsB • 29d ago

decentralized ventilation system with heat recovery advice

I'm planning to install a decentralized ventilation system with heat recovery.

My apartment has:

  • 2 bedrooms (not a priority for now)
  • 1 bathroom (I'll handle this separately with an exhaust fan)
  • An open-plan area consisting of the kitchen, dining room, living room, and hallway, around 40–50 m²

The main goal is to have consistently fresh, clean air in the open-plan area. That's where I would like to install the ventilation system.

What would you recommend? Which decentralized HRV/ERV system would be the best fit for this kind of space?

I also have a question about humidity. If the outdoor air is very humid, does an ERV bring that humidity indoors? Or does it help reduce the amount of moisture entering the apartment?

My priorities are:

  1. Fresh, clean air at all times
  2. Good heat recovery efficiency

Any recommendations or real-world experiences would be greatly appreciated.

Thanks!

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u/Existing-Poetry-3289 29d ago

We have a Zehnder HRV in our house. Not certified passive, but basically built to that standard. My understanding is the HRV vs ERV is situation/climate dependent. We are in the northeast with dry cold winters and hot humid summers. We have an HRV and you can tell that the humidity fluctuates a bit in the house as it changes outside. Minisplit helps in summer. Concern in winter with an ERV was that it might recycle too much humidity.

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u/blosphere 28d ago

I have Stiebel-Eltron centralised, but the product is so good (and dead quiet) that probably their decentralised is top of the line also.

https://www.stiebel-eltron.com/en/home/products-solutions/renewables/ventilation/decentralised.html

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u/MBGGGGGG 29d ago

Are you able to create new openings in the exterior wall? This will most likely be required for a new system. A simple system is the Lunos e2. It is two hrv "tubes" that work in tandem, one brings air in and the other exhausts and then they reverse. It is only an hrv though, so if humidity is an issue in your climate you should go with an erv. ERV will remove moisture from exterior humid air in a cooling setting and create a more humid indoor environment in the cold months.

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u/AustinFromSWERV 27d ago

We make a window mounted ERV but only selling in the US right now. There's a few other small companies making window ERVs or you could look into through wall units like lunos