HVAC Tool Validation Phase 2

The HVAC Tool is designed to estimate energy savings from commercial HVAC retro-commissioning (RCx) and operational measures, but the Phase 1 validation revealed calculation limitations that reduced stakeholder confidence and constrained broader program use. This project addressed the need to improve the tool’s technical defensibility, usability, and applicability for utility program implementation and evaluation. In Phase 2, the project team enhanced the tool’s airside, hot-water, and chilled-water system calculations through a series of targeted updates. These included revised fan curves based on the Title 24 Alternative Calculation Method, improved supply air temperature reset fan penalty calculations, zonal variable air volume minimum airflow inputs, corrected boiler calculation errors, boiler sequencing, improved hot-water reset logic, support for air-cooled chillers, refined chilled-water pump penalty calculations, and updated Climate Zone 2025 weather data. The modified tool was validated against benchmark data from real projects, Title 24 compliance models, and engineering calculations. Results indicate that the updated HVAC Tool provides improved technical consistency, reduces unrealistic fan and pump penalties, expands equipment coverage, and produces more reliable savings estimates. Stakeholder feedback also informed improvements related to transparency and usability. The project successfully met its objectives by implementing planned modifications, documenting the methodology, and validating the revised calculations. Overall, the updated HVAC Tool strengthens the credibility of savings estimates for utility program applications and provides a practical handoff package for future use, review, and maintenance. Additional recommendations were identified to further improve usability, calculation accuracy, reporting functionality, and developer-oriented documentation, supporting broader adoption across California IOU RCx HVAC programs.