The aim of this work is to investigate transient thermal comfort due to step change in environment temperature for a space conditioned by a chilled ceiling displacement ventilation (CC/DV) system and aided with a personalized evaporative cooler (PEC) directed towards the occupant trunk and face. Environmental space conditions were predicted using a steady state model, while a transient segmental bioheat model and a thermal comfort model were used to calculate comfort. The applicability of the combined space model and bioheat and comfort models in transient conditions was validated by experiments in which human participants moved from hot space to a CC/DV-conditioned space. The calculated overall thermal comfort compared well with the recorded votes with accuracy at +/- 0.3 of comfort scale from -4 (very uncomfortable) to +4 (very comfortable). The validated model was applied to a case study of single room conditioned by a 25% undersized CC/DV system. A temperature drift of 3.9 degrees C occurred with the use of 25% undersized system and associated transient discomfort was eliminated during temperature drift hours by the use of the PEC. The CC/DV-PEC system saved 7% energy when compared to a CC/DV system that provides the comfort without the aid of the PEC device. (c) 2013 Elsevier B.V. All rights reserved.