Absolutely, there are plenty of climates where HRV (aka MVHR) is quite sufficient. In inland areas (most of the US, and a fair chunk of Europe), the temperature

Absolutely, there are plenty of climates where HRV (aka MVHR) is quite sufficient. In inland areas (most of the US, and a fair chunk of Europe), the temperature difference between summer and winter is enough that a HRV is unlikely to be sufficient. Somewhere like the UK or somewhere near the equator and high altitude, a HRV system probably will be absolutely fine. In the UK, the outside air dew point in the depths of winter is likely to be between -5 and 15 °C, and in summer likely between 10 and 25 °C. That might be a little dry at the driest, and a little sticky on a couple of days in the summer, but it's perfectly reasonable to just bring that air into the house without messing with the humidity. Most UK houses are too humid and don't have enough ventilation. However, as soon as you start wanting to cool a house because the outside air is too hot, then that outside air will basically have 100% relative humidity when it is cooled to your house temperature, and it will probably have condensed out a load of its moisture onto whatever was cooling it, so you absolutely do need to mess with the humidity.