This is an odd perspective for me. Most buildings built from 1960's onward relied heavily on HVAC systems for conditioning the indoors. I would say the emphasis

This is an odd perspective for me. Most buildings built from 1960's onward relied heavily on HVAC systems for conditioning the indoors. I would say the emphasis on energy efficiency has spurred the opposite, to reduce reliance on HVAC systems by taking advantage of passive energy strategies (daylighting, solar gain etc). Also now we have much more progressive building codes specify some minimum rate of outdoor air flow (ventilation) to make sure the air doesn't get too stagnant. Caveat: this works best if you're in a moderate climate or season, then the energy efficiency strategy will likely entail trying to take advantage of outdoor air for ventilation, and also for passive conditioning if possible. If you're in a in harsh climate, yes the HVAC engineers are going to try and recover conditioned air through recirculation.