ᐅ Mechanical ventilation system

We are planning to build our single-family home using T7 bricks filled with perlite from a well-known manufacturer. We aim to meet the KfW 55 energy standard and actually exceed it to about KfW 70 with this type of brick. Because of the excellent thermal insulation, we have now decided to expand the upper floor (first floor) instead of adding four dormer windows as originally planned. This means we will need to pay close attention to ventilation, as each room would have two windows.

Now every carpenter and bricklayer is recommending a mechanical ventilation system with heat recovery. Everyone praises this system, and we feel like fools for expanding the upper floor just so we can ventilate properly. From the start, we were against installing a mechanical ventilation system and are really opposed to the idea. But today, for example, a carpenter told us about a family with a baby who cried all night because without mechanical ventilation and with windows closed, there was a severe lack of oxygen. The CO2 levels would rise extremely.

😕 We are even more confused than before. Now we are considering having ducts installed for a possible mechanical ventilation system during construction, so that if we find we absolutely need it, we could activate it later. 😕 😕 What are your thoughts on mechanical ventilation systems?

PS: We are already very conscientious about our ventilation habits.

Hello,

if you pay close attention and ventilate properly (which is not so easy to do correctly), you won’t really need a mechanical ventilation system with heat recovery (MVHR). For example, we and many others would not want to miss it for comfort reasons alone. During the cold season, humidity from cooking, showering, and bathing is no longer an issue, and in the morning, for instance in the bedroom, there is no stale air. Foggy windows also become a thing of the past. Generally, there are countless discussions about the pros and cons of MVHR/heat recovery. From an energy perspective, ventilation losses are reduced compared to correct manual ventilation. Whether the investment pays off economically in the long run remains uncertain, but the above comfort benefits are clear.

I hope this brief contribution was helpful.

Best regards...

I would also prefer a mechanical ventilation system... Insulating 4 dormers looks ugly, as dormers act like cooling fins on the roof! And the living comfort with a well-designed ventilation system is incomparably better. Besides, it saves the heat that would be lost through open windows...