Optimizing building energy consumption in office buildings: A review of building automation and control systems and factors influencing energy savings

Building Automation and Control Systems (BACS) offer promising opportunities to reduce building energy consumption, aligning with the European Union's climate goals. This review critically evaluates the accuracy of energy savings estimation in BACS implementation, with a specific focus on the European standard EN 52120-1. BACS enable effective control of various building services, including heating, cooling, ventilation, lighting, and shading, thereby improving the energy demand-supply balance while maintaining or improving comfort. The review examines energy savings reported in the literature, encompassing field studies and dynamic energy performance simulations, to assess the validity of EN 52120-1's proposed factors. Findings indicate that the factors outlined in EN 52120-1 are not sufficiently accurate in estimating energy savings from BACS implementation. Critical parameters such as occupancy rate, climate conditions, building orientation, occupancy behavior, and control algorithms are often overlooked but significantly influence BACS effectiveness. Additionally, many studies present oversimplified reference cases, leading to overestimated energy savings. While improvements in simulation parameters are necessary, building energy performance simulations appear to be the most reliable method for accurately assessing BACS savings during the design phase. By considering the complexities of building characteristics, climate models and occupant behavior, simulations provide a comprehensive evaluation of BACS performance. This review highlights the limitations of EN 52120-1's factors and emphasizes the importance of considering crucial parameters for accurate estimation of energy savings in BACS implementation. It underscores the need for comprehensive and realistic approaches to assess the energy efficiency potential of BACS in buildings, taking into account various influencing factors.