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Fan coil units (FCUs) are decentralized air-conditioning devices to locally condition zone air. In the U.S. and Europe, FCUs are widely deployed in diverse types of buildings such as offices, hotels, schools, and residential apartments because of their low cost and easy installation. The abnormal operation of FCUs due to faults or malfunctioning components may cause significant energy waste and degrading thermal comforts. However, faults occurring in FCUs have been seldom investigated. A systematic analysis of fault impacts of FCUs would enable a better understanding of fault impacts, an efficient development of fault diagnostics approaches, and an improvement of FCUs monitoring system design. In this paper, we used a FCU simulation model, which was developed in the HVACSIM+ environment from a previous study to evaluate FCU fault impacts. Five common faults with different intensities were simulated within a one-year time window to generate fault inclusive operation data. We employed a bottom-up fault impact analysis framework. Fault effects on multiple measurements were firstly evaluated to obtain fault symptom occurrence probability distributions which quantify measurements' sensitivities. Secondly, fault thermal comfort impact and fan power energy consumption impact were assessed. Lastly, the result from fault thermal comfort impacts and energy penalties was used to rank FCU faults. [ABSTRACT FROM AUTHOR]

Task-ambient conditioning (TAC) systems have proven success in reducing power consumption, improving thermal comfort and enhancing air quality. However, the adoption of TAC has, however, been generally slow. We propose an improvement to TAC systems by disconnecting them from the central air-handler, effectively making them ductless. The Ductless Task Air- Conditioner (DTAC) utilises thermoelectric modules and phase change materials for heat exchange and heat sink respectively. Prototypes of DTAC have been developed concurrently with test regimes for the proof of concept. The paper also presents the technical studies performed on the prototypes to show its capability and limitations. Whilst still in its early stages, DTAC shows promise for delivering supplementary air-conditioning to office occupants, conserving overall air-conditioning by allowing the central air-conditioner to have a higher temperature set-point and increasing occupant thermal comfort by allowing them to have direct control over their immediate thermal environment. [ABSTRACT FROM AUTHOR]