HVAC system optimization is hard work, according to an article from Building Operating Management on the FacilitiesNet website. It demands a high degree of building domain intelligence, aided by previously untapped levels of data granularity to support changes to improve space conditioning strategies. When executed properly, HVAC system optimization is as distinct from harvesting low-hanging fruit as fine literature is distinct from a limerick.
The need for accessing HVAC performance data at scale is crucial to optimizing HVAC. But you also have to know how to manage and analyze such large sets of performance data to enable permanent long-term energy savings.
Referring to low-hanging fruit as opportunities for relatively easy energy savings likely grew out of the lamp replacement era, when replacing higher wattage lamps with equivalent lumen lamps of reduced wattage, changing scores of stairwell and emergency fixtures from incandescent lamps to compact fluorescents (and later LEDs).
And adding occupancy sensors to intermittently used spaces were readily identified as easy, effective solutions to demonstrate resolve toward reducing energy use. Generous fan run-time schedules, excessive after-hours lighting, and less efficient filters on fans continued the march toward improved efficiency with quick, low-effort wins.