Analysis of economic viability of personal ceiling fans using building simulation

The present work addresses the question of economic viability of ceiling fans in comparison
to different cooling concepts for office buildings. An office building in southern Germany that
had been refurbished and supplied with a night ventilation system and ceiling fans was
modelled. This model was used to compute the parameters to evaluate the indoor air.
Occupant behaviour for working hours, window opening behaviour, and ceiling fan usage
was deduced from available models and monitoring data. The available data for the inside
air temperature served the calibration process of unknown parameters and the validation of
the whole model. Four different concepts were implemented to the model: night ventilation
with ceiling fans, as installed in the examined building, air-conditioning system, night
ventilation without ceiling fans, and a system with no cooling or ventilation. Processing the
simulation results, thermal discomfort hours due to warm indoor temperatures in the building
was assessed. Namely, the predicted mean vote (PMV) and thermal sensation vote (TSV)
were calculated and compared amongst the different concepts. A productivity evaluation
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depending on the indoor air climate served the overall economic assessment. Together with
the simulation results for the cooling energy demand and the costs related to the component
installations and maintenance, the four concepts were compared by means of the monetary
value of each. The results show a positive impact on the monetary costs of night ventilation
in comparison to the system without cooling or ventilation, as the productivity improvement
outweighs the costs of components and electricity. The benefits of an additional ceiling fan
installation are limited due to the relatively low outdoor temperatures in summer observed
at the analysed location. The positive effect is diminished further by the high investment
costs that result from the ceiling fan as custom-made solution. Future work should assess
the economic viability of ceiling fans for warmer environments.