Field study demonstrates effectiveness of fans.
Status: Completed
Funding Sources: Big Ass Fans CBE Industry Partners
Project Objective
Industrial workers in hot and humid environments are vulnerable to heat stress, which can lead to loss in productivity and reduced work capacity. In facilities where mechanical cooling would be expensive and/or impractical to install and operate, electric fans can be used to cool people as a low-cost and energy-efficient alternative to air conditioning. The objective of this project was to evaluate whether air movement from fans can effectively reduce heat strain and improve thermal comfort in non-air-conditioned manufacturing facilities, providing evidence-based guidance for protecting workers in hot manufacturing environments.
Project Results
Results show that fans significantly reduced discomfort and the level of perceived effort equivalent to a 9°F (5°C) reduction in temperature. All the workers stated that having fans in the workplace was important to them and 79% felt that they were more effective at their job with the fans running. Sublingual temperature, heart rate and sweat rate increased with ambient temperature, but did not differ with or without the electric fans. These findings show that air movement offers a low-cost, energy-efficient and effective strategy to mitigate worker discomfort and perceived level of effort and it does not worsen physiological indicators of heat stress in hot manufacturing environments.
Results show that fans significantly reduced discomfort and the level of perceived effort equivalent to a 9°F (5°C) reduction in temperature. All the workers stated that having fans in the workplace was important to them and 79% felt that they were more effective at their job with the fans running.
Significance to Industry
Many international guidelines still recommend the use of fans only up to 95°F (35°C), essentially not considering the evaporative heat loss benefits of fans above that temperature. The threshold is set at 90°F (32°C) by the US Center for Disease Control. Several studies have demonstrated that fans reduce physiological heat strain for people at rest even at temperatures in the range of 102–109°F (39–43°C) depending on humidity and the age and health conditions of the occupants. This research has led the WHO to recently change its guidelines to recognize the benefit of using fans up to 104°F (40°C). However, some researchers have cautioned that the effects of all-day or multi-day exposure to heat may not be captured in laboratory studies lasting only a few hours. Others question the realism of the subjects’ activities during highly controlled physiological studies in the laboratory. This project addresses these gaps by evaluating fan effectiveness in a real manufacturing environment with workers engaged in their typical work for the full day over several weeks.
Research Approach
The study was conducted in two adjacent, non-air-conditioned steel manufacturing buildings Baton Rouge, Louisiana. The buildings feature large openings for forklift access, allowing significant air exchange with the exterior environment. A variety of fans, including HVLS (high volume low speed) ceiling fans, wall fans and floor fans have been installed in both facilities. Over six weeks, 36 volunteer subjects were monitored under alternating fan-on and fan-off conditions. A six-week non-randomized crossover study was conducted over two separate three-week periods to capture seasonal variation. The first period took place in late May, when conditions were typically warm but milder than late summer (median afternoon outdoor temperature 88°F/31.1°C), and the second period in early August, which was characterized by hotter weather (mean afternoon outdoor temperature 91°F/32.6°C). During the May period, fans were alternated on and off on a daily basis, whereas during the August period, fans were alternated on and off in AM/PM blocks.
Physiological, environmental, and survey data were collected to evaluate comfort, perceived performance, thermal stress, and physiological strain. Air temperature, relative humidity, and mean radiant temperature were measured at multiple locations throughout both buildings. Air velocity was measured at several locations for each of the participants’ work areas under both fan-on and fan-off conditions. For physiological measurements, sublingual temperature was measured as a proxy for core body temperature, heart rate was recorded using a heart rate sensor, and sweat loss was quantified.
To quantify the relationship between indoor air temperature and subjective responses while accounting for repeated measurements within individuals, linear mixed-effects models were employed. Models included random intercepts and random slopes, allowing inter-individual variability in baseline perception and temperature sensitivity.
Publications and Reports
Huizenga, C.; Zhang, H.; Smallcombe, J.; Lyu, J.; Yang, J.; Liu, C., et al. (2026). Using Fans to Reduce Heat Stress in Manufacturing Environments. CATE 2026 Proceedings. Retrieved from https://escholarship.org/uc/item/70g4j89m