Comfort and Economic Viability of Personal Ceiling Fans Assisted by Night Ventilation in a Renovated Office Building

An expected increase in the use of air conditioning by 2050 will significantly increase electricity demand and come at a cost to the environment. Implementing passive cooling strategies and focusing on personal environmental control systems (PECSs) could help to address this issue. While numerous studies have investigated the positive impact of PECSs on thermal comfort and energy savings, their overall economic benefit has been poorly addressed. We present an economic evaluation of personal fans for an office building in Germany. Building performance simulation was used to compare passive and active cooling concepts, and sensitivity analysis was performed for different climate scenarios. A cost-benefit analysis was carried out, including an assessment of investment and operating costs and the monetary value of relative performance. The transferability of comfort and productivity into costs is the novelty of this paper. The results showed that by supplementing night ventilation with personal fans, discomfort hours could be reduced by up to 50%. However, the initial investment of the fan is not compensated by savings in productivity losses compared to night ventilation alone. A reduction in the cost of the technology could help to economically offset the investment. The results contribute to the literature on the economic evaluation of a PECS by proposing a framework to motivate its implementation in buildings

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 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