WRL or (decentralized) WRL - yes or no? Advantages and disadvantages?

Dear forum,

we are currently planning our new build and now I have the construction service specification from our builder. First of all: one thing is certain, a central ventilation system is out of the question because it is too expensive. The basic data for our single-family house: 130 sqm, ground floor and bathroom (upper floor) underfloor heating, rest radiators, all windows with shutters (thermal insulated roller shutter boxes (half shells))

[U]According to our construction service specification, the following is to be installed:[/U] "Decentralized ventilation system Lunos e² with heat recovery (up to 90%), lowest power consumption (only 0.09 watts/m² thanks to direct current) and 10 years warranty on the ceramic storage. Complete installation in the exterior wall. Exhaust fan as AB 30/60." [U]Our wall construction is as follows:[/U] - Double-shell facing masonry - total thickness of 45 cm. - Inner shell - 17.5 cm thick aerated concrete as plan stone WLZ 0.10, compressive strength PP2, brand Ytong - 14 cm hydrophobized (water-repellent) core insulation boards KDII with staggered joints WLG 035 - 2 cm air layer - 11.5 cm facing brick - U-value approximately 0.16 W/m²K - Triple-pane insulating glass as thermal protection glass (Ug value 0.7 W/m²K)

Is it really necessary to install a ventilation system? I know that it prevents mold growth and ensures controlled air exchange. But is it really necessary? I am rather skeptical about it. I have already been in several houses (built from 2013) without a ventilation system and noticed nothing negative.

So far, the disadvantages outweigh for me (my own opinion): - Increased energy consumption (electricity, heat loss) - Holes in the wall - Noise from external influences and the ventilation system itself - Energy loss in winter - Higher temperatures in the bedrooms in summer

If we now decide on a decentralized ventilation system, how many fans are needed? Where is it advisable to install them?

I would like to thank you in advance for your effort and opinions!!!

You have more heat loss without a ventilation system... you are mistaken...

Only a ventilation technician can tell you how many fans you need, but if the system is to work efficiently, it usually comes down to one fan per room... or several in larger rooms...

and then a central system is not so expensive anymore and often even cheaper...

If you can maintain the ventilation intervals, then you don't need a ventilation system... how these are can be told to you by your architect... but usually, it is daily ventilation in the morning and evening by opening windows for 5-10 minutes

I can't do that because we also have other things to do and have to work, that's why we installed ventilation in the house and we have not regretted it so far...

So now I can even report from reality - we have a controlled residential ventilation system with decentralized heat recovery. Controlled residential ventilation is definitely recommendable - it no longer smells musty or stale; not even in the morning. Opening windows is unnecessary. When it’s cold, the controlled residential ventilation also lowers the humidity. We woke up at 55% (after the night on level 1 with two people in the room) and now it’s down to 48% upstairs (after a few hours on level 4).

Disadvantages: Levels 3 and 4 in my opinion are only for parties, assembling furniture, or if you’re deaf. It also works if you’re on the other floor. If a plane is flying outside (unclear why any ever fly there, but it happened last week) you can hear it a bit. Level 2 works for normal life (unless you’re alone and paying attention). Level 1 works for sleeping.

Electricity consumption is probably balanced out by heating savings - whether that’s really the case I don’t know; but these devices don’t consume that much electricity.

Everything then speaks rather for a central controlled residential ventilation system - I never understand why anyone would install something decentralized in a new building...

Hello,
I moved in 4 weeks ago and also have the Lunos e² fans in combination with the exhaust fans in the bathroom/WC and kitchen. For 175m² of living space, we have 8 e² fans with heat recovery and 4 exhaust fans on 3 levels. Just call the manufacturer Lunos in Berlin, they gave me very good advice as well. The room climate, as far as I can judge after 4 weeks, is very good – but with 4 children we wouldn’t manage regular airing 3 times a day, so a heat recovery ventilation system was absolutely necessary.
At level 1 you can sleep comfortably, levels 2&3 we switch on only as needed. For the exhaust fans I would recommend the RA15/60 instead of the WB30/60, due to lower power consumption, quieter operation and 3 instead of 2 levels. I would also consider installing a TAC control (well described on the homepage), through which the entire system can be easily controlled. Otherwise, you control the exhaust fans individually and the e² in groups of four.
If you have more questions, feel free to ask.
Regards,

Sorry, but it’s really totally complicated – why not just have a central ventilation system? You want to make the house airtight at all costs and perforate half the facade with vent holes?

And then you always have to keep adjusting depending on the time of day/presence?