Creating thermal refuges with low‑energy cooling: effectiveness of evaporative coolers

Heatwaves increasingly endanger public health, underscoring the urgent need for low-energy cooling strategies suitable for emergency use. Among them, evaporative cooling (EC) systems represent a promising solution to create temporary thermal refuge areas with minimal energy and infrastructure requirements, especially under hot and dry conditions. However, experimental evidence on their real cooling potential, particularly under different ventilation and boundary conditions, remains limited. This study investigates the thermal performance of two EC systems, a whole-room unit and a personal-scale device, through laboratory tests in a controlled climate chamber (5 × 5 × 2.53 m) set at 32 °C. We assessed: (i) indoor air temperature and humidity offsets, (ii) spatial airflow and turbulence distributions, and (iii) cooling effects (CE) measured using a thermal manikin. We found that the whole-room EC reduced air temperature by up to 2.8 K and increased relative humidity from 15–20% up to 52%, while producing an average CE of 3 K on the manikin and over 5 K in upper body regions. When combined with a personal EC, the CE rose to 6 K, despite limited additional air temperature reduction. Spatial mapping revealed heterogeneous airflow and turbulence, which enhanced convective heat transfer. Energy demand was small (220 W and 10 W for the whole-room and personal ECs, respectively), while water consumption averaged 2.6 L/h (0.034 L/h⋅m³). These findings show that evaporative cooling can provide rapid, effective thermal relief with low energy use, offering a scalable solution for protecting vulnerable populations during extreme heat events.