Simplified HVAC Control Retrofits

Most of the commercial buildings that will exist in 2050 have already been built, and many still run their heating and cooling systems on outdated or poorly tuned controls. ASHRAE Guideline 36 (G36) offers modern control strategies proven to cut HVAC energy use dramatically — control retrofits following G36 have achieved 50 to 60 percent reductions in past demonstrations — but applying it to existing buildings is challenging given older systems, tighter budgets, and limits on what can change without disrupting occupants.This project developed design guidance that aims to simplify HVAC control retrofits, distilling G36 into a smaller set of high-value upgrades suited to real-world retrofits. The team reviewed past projects and published research, analyzed common existing HVAC configurations, and interviewed engineers, controls contractors, and utility program staff to identify the most cost-effective measures and the barriers holding back wider adoption.The result is a short list of proven, retrofit-friendly measures — smarter room-by-room airflow control, automatic temperature resets based on real-time demand, and more aggressive shutdown when spaces are empty — often achievable through software changes alone. Software-only projects in the field have delivered 10 to 25 percent HVAC energy savings with paybacks of eight years or less. Stakeholders agreed that HVAC controls remain one of the largest untapped savings opportunities, but cited unfamiliarity with G36 and a lack of standardized guidance as key barriers.This guide gives utility programs a practical tool for capturing that opportunity, particularly through Strategic Energy Management (SEM). The guide's simplified approach aligns with SEM's emphasis on ongoing operational improvement and is well suited to driving the outreach and training programs needed to build contractor and customer awareness of G36. Wider adoption could meaningfully lower operating costs while supporting long-term energy efficiency goals.