Field-measured energy savings performance of guideline 36 in retrofit implementations

Recognized as a best-in-class advanced building controls sequence for commercial buildings, the voluntary ASHRAE Guideline 36 (G36) is gaining traction in new construction HVAC controls but has seen slow adoption in retrofit cases. One explanation is that stakeholders for energy retrofit projects lack credible field evidence to justify the time and person-power investment. Most prior analyses have relied on software simulations, which overlook implementation challenges and fail to persuade decisionmakers to invest resources without a real-world value proposition based on field-measured energy performance data. This paper presents the largest known multi-site field study of G36 performance, drawing on measured results from 38 projects across diverse building types and climate zones. The analysis disaggregates outcomes by the most widely adopted G36 strategies, including trim-and-respond approaches to supply air temperature (SAT) and duct static pressure (DSP) reset, economizer controls and VAV airflow minimums and dual maximum controls. Results for controls re-programming implementations are encouraging, with HVAC savings ranging from 2%–49%, with a median of 19%. The range aligns with simulation study findings showing 1%–46% savings through these three strategies. We then present a case study from one of our 38 identified projects, detailing stakeholders’ motivating factors, implementation process by the controls team, and lessons learned. These findings show that even without capital investment in control infrastructure upgrades, existing building owners are reaping significant benefits from updating HVAC sequences of operation to industry best-practice solutions. In addition to the results giving practitioners and decisionmakers a reference point on expected energy savings benefits, the case study provides a concrete example of what a successful retrofit project may look like and provide a blueprint for implementation. Finally, utility program developers may also benefit from these findings in restructuring qualifying measures for retro-commissioning programs.