The potential of incorporating theoretically-established cool colours within the interiors of a hot humid tropical climate -as an alternative strategy for energy conservationwas tested by this preliminary field investigation with reference to a garment factory in Panadura, Sri Lanka; ventilated using ceiling fans to achieve thermal comfort. It was hypothetically assumed that cool colours can psychologically induce a relatively cool thermal perception than the real thermal condition within inhabitants, leading to a reduction of the operational speed of ceiling fans, and thereby resulting in a reduction of cooling costs. The research examined the impacts of neutral (white), warm (red) and cool (blue) colours on the indoor thermal perception of factory workers by changing the colour of the internal walls of a selected work space by the use of coloured fabric. Fan speed in five progressive levels (L1-L5), corresponding to elevating levels of power consumption, was manipulated within 10 minute intervals until the subjects reached the thermally comfortable level. The study revealed a correlation between the interior colour and the preferred fan speed. 63.63% of workers were found to achieve their perceived thermal comfort with the maximum fan speed L5 in the controled white space while, 31.81 % and 4.5 % preferred L3 and L4 respectively. A majority of the workers (86.36 %) achieved comfort with L5 when exposed to colour red, demanding high energy consumption, while 13.63 % preferred a moderate speed (L3). When exposed to blue, 63.63 % were satisfied with L5, while 9%, 13.63% and 13.63% perceived thermal comfort in L4, L3 and L2 respectively. Blue was revealed to be the most supportive colour in achieving perceived thermal comfort at a comparatively lesser level of energy consumption. Incorporating colour blue in interiors was found to be favorable and red non-favorable for energy conservation in a hot humid tropical climate.