ᐅ Centralized and decentralized ventilation: a brief experience report

Hello,

after reading many posts passively for 1 year and moving into a new build a year ago, here is a subjective report on a question that preoccupied me for a long time.
We live in a flat-roofed, solid construction house. KfW 70 standard, blower door test close to the passive house threshold. Correction regarding masonry heater with fresh air supply.

After much consideration, I wanted a ventilation system. Ultimately, we installed a Comfoair 350 with ground-source heat exchanger for our living area and, due to acoustic decoupling needs for the granny flat (around 25m² (270 ft²)), an inverter twin unit. The costs were higher than the average reported here.

My purely subjective assessment after 1 year:
Central system: noticeably quieter, mostly airflow noise. You can clearly feel the air current by placing your hand near the outlet, but it is not drafty. Central control is convenient. The ground-source heat exchanger is a nice addition; I pushed the temperature limits. On humid summer days, the air feels less "stuffy," drier. I have no sufficient experience for winter yet. The air in the first winter was already dry (25-35%), and I plan to purchase a humidity-recovering membrane this coming winter. No malfunctions so far. Maintenance: cone filters at the outlet need replacement every 3 months (non-original products, so relatively inexpensive). I use both coarse and fine filters: the coarse filter is dusted every 3 months and replaced every 6 months; F7 filter replaced once a year. Original products are quite expensive; I ordered cheaper alternatives (a German company, 5 letters, starts with S.) and will give those a try.

Decentralized system: despite internal sound insulation, the fan noise is unpleasant to me; I hardly notice any airflow. The coarse filter is washable, so no maintenance costs so far. “Swiss cheese” problem due to acoustic openings to the outside.

My conclusion for the house: central ventilation is reasonable, ground-source heat exchanger is nice to have, and it brings a significant comfort gain (e.g., no mosquitoes). Decentralized systems are more suitable for small living units.

Many thanks for the many helpful posts I read.

hexentrics

We have had a central ventilation system from Weißhaupt for three years and are satisfied with it. We always run the ventilation on the lowest setting, as we occasionally still open the windows. In summer, the advantage is that you don’t need to open the windows, so no flies or unpleasant odors from nearby sources enter the house.
In winter, you don’t waste the warm air by letting it escape outside.

I would argue that it would be possible without ventilation as well, but this way it is easier and more comfortable... so it is a bit of a luxury, too.

Since when do ventilation systems filter out odors?

Mr.Martin schrieb:
We always keep the ventilation on the lowest setting, since we also occasionally open the windows. In summer, this has the advantage that you don’t need to open the windows and therefore no flies or manure smell come into the house.

And there are also fly screens available to keep out flies.

Regarding the heat, it might even be counterproductive to run the ventilation at the lowest setting all day long. In my opinion, no ventilation during the day and as much as possible in the evening/morning/night is better. Open windows with cross-ventilation are simply more effective and quieter than running the ventilation at full power.

Sebastian79 schrieb:
Since when do ventilation systems filter out odors?

If needed, activated carbon filters can be used.

Musketier schrieb:
And there are also insect screens to keep flies out.

But dust and pollen still get through the insect screen, which an F7 filter would normally capture...

Musketier schrieb:
Regarding the heat, running the ventilation on the lowest setting all day might even be counterproductive. In my opinion, no air exchange during the day and as much as possible in the evening/morning/night is better. But open windows with cross-ventilation are simply more effective and quieter than running the ventilation at full power.

But I still need to ventilate my house during the day, and there should be a bypass for heat recovery in the unit (at least there should be). It also provides cooling at night without the system running at full capacity. The geothermal heat exchanger further supports this by removing moisture from the outside air and cooling it slightly. This makes the air much more comfortable than the humid outdoor air coming in through the windows.