Optimization-informed heuristic rules for supply air temperature reset in dedicated outdoor air systems

Dedicated outdoor air systems (DOAS) have gained attention for their benefits to indoor air quality and energy efficiency. Determining the optimal supply air temperature (SAT) under various operating conditions for DOAS is crucial for improving the system’s overall energy efficiency. So far, academic research efforts have focused on optimizing control sequences for DOAS SAT and identifying their potential energy savings. However, these optimal control sequences are often complex and dynamic, making it challenging for building operators to interpret and implement them in practice. This study aims to simplify the complex optimal control sequence by using a straightforward rule-based strategy. Decision tree algorithms were employed to develop an optimization-informed DOAS SAT reset strategy, which achieves near-optimal energy performance while greatly enhancing ease of implementation in building automation systems. The proposed optimization-informed DOAS SAT reset strategy showed energy cost savings of about 19.3% compared to a constant SAT of 21°C (70°F), and 6.0% compared to a commonly used outdoor air temperature-based reset control. These results were obtained across various building types (i.e., medium-sized offices and primary schools) and climate conditions (i.e., ASHRAE climate zones 2A, 3B, 4A, 4C, 6A, and 6B.