If three-type ventilation is used in an ultra-tight house, underfloor air conditioning heating is required.

August 23, 2018
Floor insulation is not suitable for ultra-high airtightness (C value below 0.3, etc.) + Type XNUMX ventilation. (Underfloor air conditioner is required)
This is a story I heard recently from a certain construction company.
"I live in an airtight house with three types of ventilation, and the cold air coming from the air intake and the cold floor are extremely unpleasant..."
It is desirable for the C value to be close to zero, and the closer it is to that, the cleaner the cool air will be coming in through the natural air intake.
Matsuo Design Office has tried 0.3 or less + type three ventilation several times, but has never received a complaint.
At first I didn't understand the reason, but after thinking about it for about five seconds it all made sense.
That was whether or not there was underfloor air conditioning heating.
The cold air coming in through the air intake gradually accumulates near the floor.
If the underfloor air conditioner is heating, the warmth will be more than neutralized by the warmth of the floor, but if the floor is insulated and the underfloor air conditioner is not heating, the floor surface will become quite cold.
This was an eye-opener as I had never thought about it before.