> The fact that a house needs to be pressure tested seems insane. What's the alternative, building intentionally leaky houses? Better to be able to control th

> The fact that a house needs to be pressure tested seems insane. What's the alternative, building intentionally leaky houses? Better to be able to control the leaks to your benefit, aka active ventilation. > Sure you can leave the windows open, but that defeats the purpose. Actually the purpose of wind-ows is to let the wind in - no pun, that's the actually etymology of the word, (also in Spanish: ventana originally meant "for venting"). Even in an old air-leaky house if you don't open your windows, the ventilation is happening through your walls, using them as an air filter which they were not designed to be, and in the process pulling moisture through them, which can cause all kid of bad stuff to grow in them. You shouldn't rely on such passive depressurization for ventilation, as it depends totally on pressure differences between indoors and outdoors. > Most modern houses need air condition or at least ventilation systems, because they need to be so energy efficient, that there is no other way to get fresh air in. There absolutely are ways to get fresh air in and dirty air out, including the following: - Exhaust ventilation systems (i.e. whole home extractor fans) - Balanced ventilation systems - Energy/Heat Recovery Ventilation systems. The poorly ventilated houses you are referring to were built between the 80s and 90s - yes they have ventilation issues. I know this because I own such a house and have fixed the ventilation issues with solutions from the list above. Today in most areas, some form of mechanical ventilation is required by code on new construction, and has been for 15 or so years.