On: Heat pumps of the 1800s are becoming the technolog...

[kccqzy]

I don't know; is it more energy inefficient than having a fresh air intake via a duct? Maybe they are comparable in the absence of a heat recovery ventilation system (mentioned by a sibling comment upthread)?

[BenjiWiebe → kccqzy]

Our house has a heat exchanger that exchanges air. So the outgoing air changes the temperature of the incoming air.

[mvnuweucxqokii → kccqzy]

You don't necessarily need to take in fresh air to freshen air in certain ways. It might suffice to pass it though a good filter.

[Zanfa → mvnuweucxqokii]

HEPA and carbon filters do wonders for cooking smells, particulates etc, but unfortunately do nothing for the main reason you want air exchange with outside, which is CO2 buildup.