HRV and ERV
Choosing between an HRV and an ERV
...air comes in through walls?
A reasonably tight house would have a measured air tightness of about 3 Air Changes per Hour at a pressure of 50 pascals (ACH @ 50 Pa).
For the average home (2100 square feet), this would mean about 75 m³/h or 21 L/s (44 cfm) of outside air under normal circumstances. In real terms, that...