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 improperly 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 simulation tools are systematically reviewed in terms of operating schemes of AHUs, modeling/simulation environments, type and severity of faults, climatic conditions, time-step, and duration of simulation. In particular, a detailed analysis of the impacts associated to the faults occurrence is performed 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 analyze fault impact scenarios and assist the deployment of innovative automated fault detection and diagnosis tools.