Most houses (at least in the US) are so leaky that an ERV/HRV is just going to suck all the heat out, and cold air is going to come in through all the drafty pl

Most houses (at least in the US) are so leaky that an ERV/HRV is just going to suck all the heat out, and cold air is going to come in through all the drafty places (and that doesn't necessarily mean fresh air, could be stale air from your crawl space). Wouldn't recommend for any existing construction unless you know how air tight your house is (get a blower door test done).