Faults’ Effects in Air-Handling Units: A Comprehensive Analysis of Numerical Studies

Heating, Ventilation and Air-Conditioning (HVAC) systems including Air-Handling Units (AHUs) are in charge of a significant contribution to the building sector's overall energy demand, and they frequently operate im-properly as a result of inadequate maintenance, inappropriate installation, or failures of components. In this work the most important scientific studies devoted to the assessment of faults’ impacts on AHUs performance via sim-ulation tools are systematically reviewed in terms of operating schemes of AHUs, modeling/simulation environments, type and severity of faults, cli-matic conditions, time-step and duration of simulation. In particular, a de-tailed analysis of the impacts associated to the faults occurrence is per-formed with reference to thermal comfort, cooling/heating energy demand, and electric energy consumption. This review has been carried out with the main aim of highlighting the most significant research gaps as well as the most adverse faults’ effects; as a result, it will serve as a roadmap for the creation of new and precise AHU simulation models that will be used to ana-lyze fault impact scenarios and assist the deployment of innovative automat-ed fault detection and diagnosis tools.