[dgacmu]

+this.

Another way of putting it: A well-designed structure should minimize random, unintentional air exchange, but provide sufficient deliberately-engineered ventilation to keep the air and people happy. For efficiency, that ventilation should go through a heat recovery ventilator (HRV) or energy recovery ventilator (ERV) as appropriate to the climate and budget. (An energy recovery ventilator also exchanges moisture).

Beyond Chlupp, Lstiburek is a great engineer and writer on these topics.

[snicker]

Perhaps I lacked the verbosity in my original comment, but this was what I meant to imply: ventilation is part of the design. Unintentional exchange is to be avoided.