Decentralized vs. Central Controlled Residential Ventilation? Points for KfW House Calculation

... does anyone have any idea about the calculation of the air exchange rate?

DIN 1946-6!

...Humidity and poor air quality almost only occur when people are present, right? That the house should be ventilated just as often during absence/vacation etc. as when occupied seems rather illogical to me at first! Are there any opinions on this?

Here too, DIN 1946-6 with its different ventilation levels applies. This sometimes results in quite different air exchange rates compared to the mentioned 0.5/h.

best regards

Of course! It is not without reason that the thermally effective air volume flows must be taken into account, for example in the heating load calculation. The better a building is insulated, the more noticeable and sustainable the effect of heat recovery.

v.g.

Excuse the silly question, but would I drop from a Kfw 70 house down to Kfw 55 with a controlled residential ventilation including HRV, or does it not matter in this case? As already mentioned, we then use district heating at the location with a primary energy factor of 0.11.

Best regards

Hello,

Humidity and bad air arise almost only when people are present, right? That you should ventilate the house as often during absence/vacation etc. as when present seems rather illogical to me at first glance! Are there any opinions on this?

DIN and TGA-technical information can be provided to you better by €uro than anyone else here; I tend to go more with practice.

Have you ever been in a house that was "vacant" for a longer period? Mhm ... it smells bad ... recently I had the "pleasure" to visit one where a water pipe - for whatever reason - had burst.

In a new building, there is also always water involved; even in prefabricated houses. This water must be transported out, by the way, extremely important in the first 2 years. Later on, with usual shock ventilation, you hardly manage to get the human-produced breathing/cooking/bathing water - before the vacation - out of the rooms. That is why a key is always deposited either with the family or the neighbors; thanks to hydroponics, flowers can also survive longer without care.

Best regards

Hello €uro,

You know, I really appreciate your answers and would like to see more of them

The true value of a Controlled Residential Ventilation is measured by comfort

Here I am 100% with you.

and the Controlled ventilation. The price difference of a Central Controlled Residential Ventilation without heat recovery and with heat recovery is not as significant as often assumed.

Not as small as you imply here, unfortunately; measured against the total volume of new construction, again negligible.

The "cooler" the climate location, the more effective the Controlled Residential Ventilation with heat recovery. It is also always sensible to consider the Controlled Residential Ventilation in connection with the other system technology. The Controlled Residential Ventilation with heat recovery partially significantly reduces the heating loads, which means that, for example, with a heat pump as a heat generator, often a unit of a smaller capacity can be chosen. This saves several thousand €, especially with ground-source heat pumps, since here not only the unit but also the source becomes cheaper. The additional expense for heat recovery often disappears and it results not only in an investment saving.

With a passive house, I agree with you; however, the vast majority of builders do not indulge in a passive house.

For the majority of today's houses, although today they are built tighter than ever before – the heat recovery does not really pay off; except for the structural engineer on paper, which I still consider a deceptive scheme. Also, at not every location is a heat pump or even a ground-source heat pump usable! It is not that easy to heat 22° warm room air from outside air – for example, 0°. This requires additional technology and thus generates additional costs; a spiral without end, which the ladies and gentlemen in Brussels gleefully spin seemingly. Whether all this makes sense is another matter

I would be satisfied if each construction project were considered individually based on its respective parameters and corresponding recommendations were made. Imposing Energy Saving Ordinance requirements, targeted misinformation from the selling industry, or even scaremongering rather achieves the opposite.

Kind regards

Hello construction expert,

...As small as you suggest here, unfortunately not; measured against the total volume of new construction, however, negligible.

I always try to establish the overall context, because, in my opinion, an extreme overvaluation of individual details rarely leads to a overall satisfactory solution.

...In the case of a PH, I agree with you; however, the vast majority of builders do not afford a PH.

I see it somewhat differently, but we don't have to always agree. Whether a PH makes sense is another matter.

...heat recovery is not really cost-effective; ...

As I said, I see it somewhat differently, although here too, the individual case always counts. Generalizations rarely really help.

...except for the structural engineer on paper, which I still consider a sham.

Here I am with you again. What one sometimes gets in their hands here is more than questionable.

...It would already be enough for me if each construction project were considered individually based on its respective parameters and recommendations were made accordingly.

This possibility basically exists, it is just not utilized, probably because it's not so convenient.

...Imposing energy saving ordinance requirements, targeted misinformation from the selling industry or even scaremongering rather achieve the opposite.

This helps the builder little or even harms them, but sellers have no reason to complain.

Best regards

Excuse the silly question, but would I drop from a KfW 70 house to KfW55 with a controlled residential ventilation system including heat recovery, or does that not matter? As already mentioned, we use district heating with a primary energy factor of 0.11 at the location.

Best regards

Hi €uro,

could you possibly say something about this as well?