Commercial Office Complex – Retro-Commissioning (RCx)

This office complex in Chapel Hill, North Carolina, includes multiple multi-story buildings totaling more than 260,000 square feet. The buildings are served primarily by rooftop units and VAV distribution. Michaels Energy supported a retro-commissioning effort at the site to identify opportunities for energy efficiency improvements across several buildings in the complex.

Opportunities for Savings

Two Find-and-Fix studies were performed on site. The first study, which covered Buildings I-IV, identified two significant opportunities:

• Rooftop units were scheduled even when some floors were unoccupied.
• Supply fans operated to a fixed static pressure setpoint, regardless of how many zones called for air, and economizers and optimal start logic were configured conservatively.

The second study at Building V revealed inefficiencies that originally stemmed from responses to occupants’ complaints about comfort. Over time, relaxed controls led to the air handling units running while spaces were unoccupied, including one unit that 24/7 to keep occupants comfortable.

Solution and Results

Michaels Energy helped the property managers implement a set of operational fixes in buildings II-IV:

• Refined scheduling so RTUs and floors track actual leased occupancy, reducing hours and eliminating conditioning of empty floors.
• Static pressure reset on the RTU fans, lowering static when VAV damper positions indicate lower airflow needs.
• Economizer tuning and an optimal start sequence that better leverages outdoor air and shortens pre-occupancy runtimes.

In Building V, the customer was able to thread the needle between comfort and efficiency by implementing scheduling changes that reduced HVAC runtime to match actual occupancy patterns while still supporting tenants’ business hours.

Across all buildings in the complex, these measures deliver verified annual savings of about $34,000 and 423,000 kWh, cutting emissions by roughly 264,000 pounds of CO₂ per year.

With schedules and resets now in place, the customer can use trend data from the BAS to fine-tune further if desired. In Building V, comfort issues were addressed through smarter control rather than brute-force runtime, providing a more efficient baseline and a template it can replicate across other tenants in its portfolio.