Effect of Ceiling Fans on Core Temperature in Bed‐Resting Older Adults Exposed to Indoor Overheating

ABSTRACT Background Rising global temperatures have increased indoor overheating risks, posing significant health threats to vulnerable populations, particularly older adults. While electric fans are recommended for cooling at temperatures up to 40°C, the efficacy of ceiling fans in very warm indoor temperatures (~31°C) remains understudied. This randomized study evaluated the efficacy of ceiling fans in reducing core temperature and cardiovascular strain among bed‐resting adults exposed to simulated indoor overheating (31°C, 45% relative humidity) for 8 h. Methods Twenty participants (12 females, median IQR age: 71 68–73 years) underwent two experimental exposures with a ceiling fan set at either 0 m/s (control) or ~1.5 m/s (fan condition). Results The primary outcome, peak core temperature, was significantly lowered by 0.2 95% CI: 0.1–0.3°C (0.4 0.2–0.5°F, p < 0.001) with fan use (mean SD) 37.6 0.2°C (99.7 0.4°F); +0.9 0.3°C (+1.6 0.5°F) vs. pre‐exposure) compared to control (37.8 0.2°C (100.0 0.4°F); +1.1 0.5°C (+2.0 0.9°F) vs. pre‐exposure). Secondary outcomes, including core temperature area under the curve, peak and end‐exposure heart rate, fluid consumption, and thermal discomfort, were also reduced significantly with fan use. Despite these improvements, fan use did not completely ameliorate heat‐induced physiological strain. Conclusions These findings indicate that while ceiling fans significantly reduce heat‐related physiological strain under the conditions tested, they are not wholly efficacious as standalone cooling solutions. A combined “fan‐first” approach, integrating fans with ambient cooling strategies, may enhance heat–health protection in older adults. ClinicalTrials.Gov Identifier NCT06142890