A practical approach for measuring the energy-saving potential of building operation.

This study introduces an innovative, simple, and effective approach, the ‘9 + 1 method’, for quantifying the energy-saving potential of different operational strategies of HVAC systems in buildings. Driven by industry needs and practical ap-plication constraints, the method can be used by researchers and engineers to evaluate the impact of optimizing different energy generation and supply systems, including heating, cooling, and ventilation units. The method employs a 10-day cycle with 9 days of predictive energy optimization followed by a ‘standard’ operation baseline day. This provides a reliable approach for building operators and technical managers to test various changes, modifications, improvements, and management measures on various levels and evaluate the corresponding energy savings. It includes an in-depth analysis of energy usage in different HVAC sub-systems of a use-case scenario and assesses the impact of random weather and operational events on energy savings, using both simulated and real-world data. The method demonstrates robustness against random weather and external events, with an expected error level below 0.76% for the whole HVAC system and below 1.11% for different energy subsystems, at a 99% probability. The validated method is then used to evaluate the efficiency of different HVAC energy management strategies through simulations using EnergyPlus, highlighting the effectiveness of the 9 + 1 method in measuring energy savings. A final discussion underscores the need for a consistent and standard method for energy savings measurement. This is crucial for informed energy management and the ad-vancement of sustainable practices in building operations to attain energy and environmental goals.