Advantages and disadvantages of different ventilation systems

Hello everyone,
we are considering building and are currently having initial discussions with relevant providers. So far, we have spoken with three companies and find a different ventilation concept in each offer:

Danwood: Central ventilation system with heat recovery

Heinz von Heiden: Central exhaust system with passive fresh air supply without heat recovery (in bathroom, kitchen, utility room the air is actively expelled outside by fans; in the other rooms air is passively drawn in through appropriate openings)

Scanhaus Marlow: Only window-frame ventilation is included as standard. For an additional charge, there is a decentralized ventilation system with heat recovery.

At the moment, we are quite unsure about the advantages and disadvantages of the different systems and do not really know which direction to take. Therefore, we would appreciate expert feedback.

Specifically, the following questions arise for us:

What is the noise level like with the different systems? Especially with the decentralized system, I wonder how loud the fans are that are installed in every wall. I imagine it would be rather unpleasant in the bedroom if there is a constant humming or buzzing sound.

How noticeable is heat recovery? The system from Heinz von Heiden lacks it entirely. Does such a feature significantly affect heating costs or is it negligible in new buildings?

Are there possibly hygiene problems with the central systems after several years? There are relatively long ducts throughout the house that cannot easily be cleaned if something starts to rot.

Is it possible to install pollen filters or even activated carbon filters in decentralized systems? Or is that exclusively reserved for central systems?

How would you assess that Scanhaus Marlow installs only window-frame ventilators in the basic equipment? According to the advisor, ventilating twice a day should be enough to prevent mold problems. However, I am rather skeptical after having read up on the subject and tend to build with a ventilation system.

What is the noise level like with the different systems?

Windows: inaudible, but noise from outside
decentralized: depending on the system from not at all to slightly audible (also depends on your perception)
central: normally inaudible, slight humming only at higher power
==> all variants work well regarding noise levels

How noticeable is heat recovery? The system from Heinz von Heiden lacks it completely. Does something like that make a noticeable difference in heating costs or can it be neglected in new builds?

There is currently a parallel discussion. Yes, it is noticeable. But the lower your heating costs, the smaller the effect. I heat my 120sqm with well under €400 per year (including hot water). The ventilation is actually more expensive than simple window ventilation (electricity, filters, purchase costs). But I wouldn’t focus on costs because the comfort gain is enormous. After all, you are building instead of renting, which in the long run is probably the cheaper alternative anyway.

Are there possibly hygiene issues with central systems after a few years?

No.

Is there the possibility to install pollen filters or even activated carbon filters in decentralized systems?

Of course! I don’t know about activated carbon filters though, and I also wouldn’t see a reason to install them. In my ventilators I have both a coarse filter and a fine filter that removes all pollen.

How would you assess that only installs window rebate vents in the basic equipment?

That makes Scanhaus Marlow "cheap." A sign of a budget provider. You can do that if you have so little budget that there’s nothing left for a ventilation system (whether central or decentralized). For me, that would be a deal-breaker.

If already new build, then with a central system. No budget for that or in renovations, then decentralized. Window ventilation only for fresh air fetishists who can’t live without open windows and need the "feeling."

How is the noise level with the different systems? Especially with the decentralized system, I wonder how loud the fans are, which are installed in every wall. I imagine it would be quite unpleasant in the bedroom if there is a constant rustling or humming sound.

We currently have a decentralized system in the bedroom of our rental apartment. It is clearly audible. Personally, I don't care at all, I sleep like a log, but it bothers my husband. We are now installing a centralized system in the new building and before that we "tested" it at friends' houses. You can't hear anything during normal operation, only at most in "party mode". One family even has the ventilation device in the attic directly above the bedroom, and there you only hear something in party mode, and that is still quieter than our decentralized clunky box.

Are there possibly hygiene problems with the centralized systems after several years? You have relatively long ducts throughout the house, which you can't just clean easily if something should start to rot there.

Friends built with central ventilation about 8 years ago and recently had a particle measurement (mold spores) done due to exactly these concerns around the birth of their first child. It was inconspicuous.

Hello everyone, we are considering building and are currently having initial discussions with relevant providers. So far, we have spoken to three companies and find a different ventilation concept in each offer: Danwood: Central ventilation system with heat recovery Heinz von Heiden: Central exhaust system with passive supply air without heat recovery (in the bathroom, kitchen, utility room the air is actively discharged outside by fans; in the other rooms air is passively drawn in through appropriate openings) Scanhaus Marlow: Standard only includes window rebate ventilation. For an additional charge, there is a decentralized ventilation system with heat recovery. At the moment, we are quite uncertain about the advantages and disadvantages of the different systems and do not really know which direction to take. We would therefore appreciate expert feedback. In particular, we have the following questions: How is the noise level with the different systems? Especially with the decentralized system, I wonder how loud the fans are, which are installed in every wall. I imagine it would be unpleasant in the bedroom if a constant rustling or buzzing can be heard. How noticeable is heat recovery? The Heinz von Heiden system lacks it completely. Does this have a significant impact on heating costs or can it be neglected in a new build? Are there possibly hygiene problems with the central systems after a few years? There are relatively long ducts throughout the house that can’t just be cleaned easily if something starts to rot. Is there also the option of installing filters for pollen or possibly even activated carbon filters in the decentralized systems? Or is this reserved exclusively for central systems? How would you assess that Scanhaus Marlow only installs window rebate ventilators in the basic configuration? According to the advisor, ventilating twice a day is apparently enough to avoid mold problems. I am rather skeptical after reading on the subject and tend to build with a ventilation system.

Look up the discussion "Is a ventilation system worthwhile?" here in the forum. Much has already been said about the advantages and disadvantages. Regarding the mold problem, I can tell you that it actually works well without a ventilation system (and without window rebate ventilators); we have had this for almost 4 years now in our KfW55 house. We open windows in the morning and evening and keep doors open often enough during the day through daily life. Whenever possible, our windows and doors are open as well. Whether you see the system as a comfort gain and want to have it is ultimately a decision you must make alone; besides money, it also costs space.

we are considering building and are currently having initial talks with the respective providers. So far, we have spoken with three companies and find a different ventilation concept in each offer:

Danhaus, Heinz von Heiden and Scanhaus Marlow are already quite a diverse mix, and the ventilation systems are roughly the seventh decimal place when it comes to differentiating this applicant field. That you are open to considering Holzer and Steiner on equal footing is very good. But the selection between these candidates on the one hand and via Excel spreadsheets on the other hand is a sign of your amateurishness to a degree that requires advice and support. You should read a lot sideways here at least. Danhaus is a fairly recommendable Holzer, which has already proven to be competitive with the Steiner Viebrockhaus for me. Scanhaus Marlow, on the other hand, is a cheap provider with near-self-build standards. And Gabriele’s favorite Heinz, in my view, only has two really strong departments, namely marketing and legal. Anyone who then shows an approach like yours, in my opinion, is more likely to become a victim than a king customer.

With which house design did you even approach these companies, and who else belonged to the participant field before this semifinal? Read up here on the keywords dough resting / setting the course to understand how I proceed for my advisees during comparisons.

I would not compare Danhaus with Scanhaus Marlow; Hanse Haus would come to mind here instead. Among the Steiners, I would take a regional owner-managed one, which does not apply to Heinz von Heiden.

There is currently a parallel discussion running.

that would be this one:

A controlled residential ventilation system is not quite standard in the sense that there are still cars with manual transmissions and crank windows, but automatic or DSG and electric windows are already far advanced at least at the forefront of moving from niche to mainstream. If you want controlled residential ventilation, the decentralized solution is only recommended in exceptional cases for new builds, as the central solution with full supply is more cost-effective (and heat recovery in a pool works better than unconnected). I find window gap ventilation okay, but to mention it in the same breath as ventilation systems is a joke.

the costs involve not only money but also space.

Small note: decentralized not at all (regarding the topic of taking up space). For example, there are also versions for window reveals and even with a cross-flow heat exchanger (i.e. 1:1 like the central system), so that the noise levels also approach zero.