Is airtightness necessary?

I’m concerned an airtight house will be stuffy and unhealthy, is airtightness necessary? Airtightness ensures that you are getting your money’s worth when it comes to insulating value of your home. We like to think of it as a windbreaker over a woolly jumper. No matter how thick your woolly jumper is, if you go out in the wind, you can feel the wind coming through.  Why spend money on excellent insulation if you let the wind take away its thermal performance? The challenge with any home, whether it is airtight or not, is that it needs mechanical ventilation – active movement of air, NOT passive via windows and gaps in the insulation. In short – airtightness = thermally efficient. Ventilation = healthy air quality.