Tightness in a passive house
If I had to point to, what element of energy-efficient houses currently being built is
a) the most underrated
b) worst done
c) cheap to achieve but requiring precision and accuracy
then I would point to the air tightness of the building.
In buildings with gravity ventilation, the house leakage was necessary for proper air exchange. The situation is different in houses with installed recuperation. Here, any uncontrolled air flow is economically disadvantageous.
The air flow can be determined using the so-called. the n50 coefficient, that shows us, how much air (building cubature) will change at differential pressure 50 Well . For passive houses, it is less than 0,6, for houses with mechanical ventilation - less than 1,6.
Now let's consider - with what care is placed a vapor barrier in the attic or at the junction of the knee wall with the truss?, how accurately windows or doors are installed? With what accuracy are the culverts of pipes and cables brought from outside to the building designed? And it's not about a few centimeters long holes, millimeter gaps can in total cause very large heat losses. There are relevant calculations in many places on the Internet and I advise you to read it, the surprise may be quite a bit.
And so the investor spends a lot of money on a good recuperator, thick warming and then wonders why the effect is so weak? For example, minor, millimeter leaks can cause, that the heat recovery from the recuperator will drop by 15% - it was possible to buy a recuperator cheaper by several thousand, eliminate these leaks and the effect would be the same ...
An additional problem is moisture, which condenses from the cooled air escaping through the fracture. Most often in Polish construction conditions, Unfortunately, it condenses in the mineral wool insulation layer, first of all - causes its destruction, secondly - wet mineral wool is no longer a thermal insulator. So the loss is double.
How to measure the air tightness of a house?
Professionally - with a special device, which are put in place of the door. This device is equipped with a fan and special sensors and analyzers. However, this is not a cheap service, however, its cost continues to decline. Such an examination is also obligatory for the home, who wants to get a passive house certificate (for those interested - please search for the phrase test blower door)
Unprofessional - turn on the supply fan alone in the house (turn off exhaust in the recuperator) and look at the barometer - whether the pressure is rising. (If not on the barometer, then we should 🙂 If not - explore every room and using quite home methods - a candle, smoke - look for leaks. This is not a professional study and will not give professional results - but for home use - why not (If you are interested, please visit the Murator forum)