I installed a Zehnder ComfoAir Q ventilation system in my home. It has heat and moisture recuperation capabilities. It's currently refreshing the air at around 100m³/hour. It has an F7 (aka "ISO Fine" or "MERV 13") filter. Since installing it, my asthma has improved a fair bit, and I'm sneezing a lot less. Added benefit, virtually no mosquitoes have been able to enter my home. I'm still considering getting an extra filter addon to filter out more fine soot from car exhaust etc, but even without that option I've been very happy with the results.
Edit: hit reply too soon. Wanted to add: are air purifiers as effective as increased ventilation? Should we combine the two?
That Zehnder unit is fantastic. The filter, not so much. (“ISO Fine” is IMO particularly embarrassing. It should say something more like “ISO ePM 1 40%”, and then buyers would think “40%? that’s lousy!”). Even the fancier ComfoWell filter is crap. And they’re overpriced, have lots of resistance, and don’t last long. You can confirm how poorly it works with a portable particle counter.
And consider putting it upstream of the Zehnder unit in the outdoor intake duct. Then it will extend your ISO Fine filter’s lifetime to effectively infinity. Or you could replace it with ISO Coarse. Or with nothing :)
I've installed HRV myself too. I have a reasonably easy to access roof space, but for a large guy still took over half a day. Cost 1.5k NZD, but not mosquito free, it's warmer indoors plus when neighbours fire up their fireplaces I only get an occasional little whiff of it.
Because my CO2/VOC levels are low enough that keeping in on all the time doesn't provide any additional benefit- while adding unwanted cool/hot air (no ERV is 100% efficient). The minimum airflow on my unit is 35 CFM (~60 m3/hr).
That makes sense. Though I imagine that depending on where your CO2 sensors are, it could take a while for higher concentrations to reach the sensor, and then more time for the concentrations to go down once the fan starts spinning.
One of the reasons why mine also runs when I'm away is that it helps prevent mould growth in the heat/moisture exchanger, as that thing is a bit of a pain to clean.
Edit: hit reply too soon. Wanted to add: are air purifiers as effective as increased ventilation? Should we combine the two?