02386nas a2200181   4500008004100000245007500041210006900116520176700185653002301952653001501975653001601990653002802006653002202034653002402056100002002080700001902100856008502119       2017                        eng d00aModeling of HVAC Operational Faults in Building Performance Simulation0 aModeling of HVAC Operational Faults in Building Performance Simu3 a<p class="06BodyMaintext">Operational faults are common in the heating, ventilating, and air conditioning (HVAC) systems of existing buildings, leading to a decrease in energy efficiency and occupant comfort. Various fault detection and diagnostic methods have been developed to identify and analyze HVAC operational faults at the component or subsystem level. However, current methods lack a holistic approach to predicting the overall impacts of faults at the building level—an approach that adequately addresses the coupling between various operational components, the synchronized effect between simultaneous faults, and the dynamic nature of fault severity. This study introduces the novel development of a fault-modeling feature in EnergyPlus which fills in the knowledge gap left by previous studies. This paper presents the design and implementation of the new feature in EnergyPlus and discusses in detail the fault-modeling challenges faced. The new fault-modeling feature enables EnergyPlus to quantify the impacts of faults on building energy use and occupant comfort, thus supporting the decision making of timely fault corrections. Including actual building operational faults in energy models also improves the accuracy of the baseline model, which is critical in the measurement and verification of retrofit or commissioning projects. As an example, EnergyPlus version 8.6 was used to investigate the impacts of a number of typical operational faults in an office building across several U.S. climate zones. The results demonstrate that the faults have significant impacts on building energy performance as well as on occupant thermal comfort. Finally, the paper introduces future development plans for EnergyPlus fault-modeling capability.</p>10aenergy performance10aenergyplus10ahvac system10aModeling and simulation10aOperational fault10aThermal comfort  1 aZhang, Rongpeng1 aHong, Tianzhen  uhttps://simulationresearch.lbl.gov/publications/modeling-hvac-operational-faults01991nas a2200109   4500008003900000245008300039210006900122520156300191100002001754700001901774856008801793       2016                          d00aModeling and Simulation of Operational Faults of HVAC Systems Using Energyplus0 aModeling and Simulation of Operational Faults of HVAC Systems Us3 a<p>HVAC operations play a significant role among various driving factors to improve energy performance of buildings. Extensive researches have been conducted on the design efficiencies and control strategies of HVAC system, but very few focused on the impacts of its operational faults on the building energy efficiency. Modeling and simulation of operational faults can lead to better understandings of the fault impacts and thus support decision making of timely fault corrections which can further benefit the efficient system operation, improve the indoor thermal comfort, and prolong the equipment service life. Fault modeling is also critical to achieve more accurate and reliable model calibrations. This paper introduces the modeling and simulation of operational faults using EnergyPlus, a comprehensive whole building performance simulation tool. The paper discusses the challenges of operational fault modeling, and compares three approaches to simulate operational faults using EnergyPlus. The paper also introduces the latest development of native fault objects within EnergyPlus. As an example, EnergyPlus version 8.4 is used to investigate the impacts of the integrated thermostat and humidistat faults in a typical office building across several U.S. climate zones. The results demonstrate that the faults create significant impacts on the building energy performance as well as occupant thermal comfort. At last, the paper introduces the future development plan of EnergyPlus for the further improvement of its fault modeling capability.</p>1 aZhang, Rongpeng1 aHong, Tianzhen  uhttps://simulationresearch.lbl.gov/publications/modeling-and-simulation-operational