PG&E HVAC Tool Validation

The project team evaluated the alignment between energy savings estimates derived from a modeling tool (Tool) and those generated by whole building energy modeling, focusing on both air side and hot water system measures. Overall, hot water system measures exhibited better alignment, with simpler base case energy consumption and savings relationships compared to the more complex air side systems. Air side measures such as equipment replacement, scheduling optimization, economizer optimization, static pressure reset, and fan setback demonstrated good agreement between the Tool and modeling estimates, with average errors under 5% for both electricity and heating. However, discrepancies arose for supply air temperature (SAT) reset and space temperature setback, with the Tool either overestimating or underestimating savings due to limitations in how it handles detailed control strategies and fan savings. For hot water system measures, the Tool generally aligned well with modeling for boiler and pump specifications, HW plant lockout control, and pump VFD control. However, for hot water temperature reset, the Tool overestimated savings due to its handling of jacket loss reduction, which differs from the modeling approach. The project team provided recommendations to improve the Tool’s accuracy, particularly for measures where significant misalignment was observed. While it is unclear whether these improvements will bring Tool estimates fully in line with modeling results, they are expected to enhance the validity of the Tool’s assumptions and calculations. Given that whole building modeling, while highly accurate, can be time-consuming and costly, the Tool serves as a viable alternative for estimating energy savings in less complex projects.