In the Nordics the baseline is triple glazed windows and mechanical ventilation with exhaust air heat recovery. I'm sure doing the same elsewhere would be a good start at least

Neither of those things matter for air exchange.

I don't think I then understood your comment about air quality concerns. What's the concern if ventilation works fine and energy efficiently?

Place a well insulated wall in the middle of a field. Add a tripled glazed window and 100% efficient ventilation. Which side of the wall is warmer than the other?

Ideal indoor air quality is equal to outdoor air quality. This can only be achieved through air exchange. The ventilation process may be 100% efficient but the consequences of pumping outside air in and inside air out are the same. The air must be heated and costs some unit of energy to accomplish.

That's why the heat recovery is done. It of course doesn't get all the heat, but AFAIK can capture some 80%. This is in use and widely deployed.

https://en.wikipedia.org/wiki/Heat_recovery_ventilation

> Ideal indoor air quality is equal to outdoor air quality.

Ideal indoor air quality is (can be) better than outdoor air quality. This is because when the outside air is brought in it passes through filters to get rid of things like dust and pollen.

> The air must be heated and costs some unit of energy to accomplish.

Unless you use passive solar thermal, i.e., let the sun heat the home:

* https://www.energy.gov/energysaver/passive-solar-home-design

Modern mvhr systems are 90-odd% efficient. The losses through proper ventilation are small enough.

> And air quality concerns. You need to ventilate your home with outside air year round.

Look up HRV/ERVs.

You'll have better air quality by building a tight envelope and using mechanical ventilation because all the air from the outside will flow through filters. It then gets tempered by the exhausted stale air before being circulated.

A leaky house and ventilation through windows was fine in the 1920s, but we've better ways now.

(And operable windows won't go away: they're mandated for fire egress. So you can crack one open if you wish.)

Ventilation and insulation are orthogonal. The passivhaus standard puts ventilation front and centre and has exceptionally high efficiency targets overall.