The other upside to sealing plus mechanical ventilation (instead of leaky-building ventilation) is that your building is always fresh. Leak-driven ventilation leads to a building that is drafty on windy days and stuffy on calm days.
Plus if the leaks involve air circulating though insulation in the cavity or attic, whatever is in there will end up in your house air. That could be dust from construction, parts of the insulation material, or decomposing rodents.
Is the 3 months interval a regional thing, or based on the heat exchanger? Mine have 1 year intervals, and with a subscription for filters it is easy to remember to change the filters
>Is the 3 months interval a regional thing, or based on the heat exchanger?
both. That is it varies between different units but also varies with local conditions, if your local conditions are "heavy-duty" (very high humidity, smog, area with lots of dust or lots of pollens etc.) you should consider replacing more frequently than rated intervals.
