Building HVAC engineering (equipment sizing, ducting design, etc.) has been largely handwavy bullshit for a very long time and only recently has moved towards any sort of precision. Not uncommon to find boiler plants that are 3-4 times the maximum heating load in the winter, or fans running at 100% 24/7 when code only requires half of that.
Costs just get passed on to tenants so there was never much motivation to do better, the only reason building owners are moving now is because of government regulation and incentive programs.