Regular Maintenance and Commissioning — The Foundation of Commercial AC EfficiencyCommercial HVAC systems are complex, expensive assets that degrade in performance over time if not properly maintained and periodically recommissioned. Studies by the California Energy Commission and Lawrence Berkeley National Laboratory have found that HVAC maintenance and recommissioning deliver some of the highest returns of any commercial energy efficiency investment — often at very low cost.The Performance Degradation ProblemA new commercial HVAC system, properly designed and installed, typically operates close to its rated efficiency. Within 5–10 years of service, however, drift accumulates: sensors drift out of calibration, damper actuators stick, filters clog, coils foul, refrigerant levels drop, and control sequences develop anomalies. Each issue individually may seem minor, but collectively they can increase energy consumption by 20–40% compared to original performance.Preventive Maintenance EssentialsA rigorous commercial HVAC maintenance program addresses:Coil cleaning: Fouled evaporator and condenser coils can reduce heat transfer efficiency by 20–30%, forcing compressors to work harder. Annual cleaning is the minimum; semi-annual is recommended in dusty or high-use environments.Filter management: Commercial air filters must be changed or cleaned on schedule. Dirty filters increase static pressure, forcing fans to work harder and reducing airflow.Belt and bearing inspection: Fan belts stretch and wear, reducing drive efficiency. Bearings develop friction as they age. Regular inspection and replacement prevent efficiency losses and catastrophic failures.Refrigerant leak detection: Even small refrigerant leaks degrade system performance significantly. Annual leak checks are standard in good maintenance programs.Controls calibration: Thermostat and sensor calibration ensures the system is responding to accurate data. A thermostat reading 2°F high can cause significant unnecessary cooling.Retro-CommissioningCommissioning is the process of verifying that a building’s systems are operating as designed. Retro-commissioning (RCx) applies this process to existing buildings — identifying and correcting operational deficiencies that have developed over time. Typical RCx findings include:Simultaneous heating and cooling (systems fighting each other)Economizer dampers stuck closed (preventing free cooling from outdoor air)Supply air temperatures set too coldVariable speed drives not functioningSchedules not matching actual occupancyLawrence Berkeley National Laboratory research found that RCx delivers median energy savings of 16% across commercial buildings, with a median payback period of 1.1 years — among the best returns available in commercial energy efficiency.Ongoing CommissioningLeading organizations implement ongoing or monitoring-based commissioning: using real-time data analytics from BAS systems to continuously detect performance anomalies and flag them for correction. This prevents the gradual drift that makes periodic RCx necessary and maintains peak efficiency year-round.