Everyone involved with IAQ knows about the 1970s, when excess energy use became Public Enemy No. 1 for commercial building designers. Saving energy was the critical goal: Air leaks were being hunted like wild animals, and windows and doors were sealed so tightly that not a breath of conditioned air could seep out.
And the fuel economizer, the behemoth that recirculated conditioned air and milked every possible Btu from it, became the hero of the day.