Enhanced Night Cooling of Low-Energy Buildings Using Directed Ventilation
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buildings-16-02078.pdf
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2.63 MB
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Adobe PDF
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f70fb3601f6766116c6b66e66fdac131
Author(s)
Kongoletos, Johnathan
Glicksman, Leon
Date Issued
May 23, 2026
Journal
Buildings
Publisher
MDPI
Citation
Kongoletos, J.; Glicksman, L. Enhanced Night Cooling of Low-Energy Buildings Using Directed Ventilation. Buildings 2026, 16, 2078. https://doi.org/10.3390/buildings16112078
Version
Final published version
Abstract
Night ventilation coupled with thermal mass is an effective means of reducing overheating in passive buildings. Successful systems require a high airflow rate coupled with enhanced convective heat transfer to the thermal mass. This work presents results for enhanced convection when the primary thermal mass is in the ceiling. Such mass distribution occurs, for example, in multi-story apartments in developing economies. Experimental results are measured in a scale model of a typical room. The original contribution is the use of upward-directed ventilation at an angle of 30° to 40° from a window located at a typical distance below the ceiling. At scaled air change rates of 4.9 air changes per hour, the measured convective heat transfer coefficient at the ceiling was 7.7 W/m2 K. In contrast, when air flowed horizontally from the window, the heat transfer coefficient was 3.5 W/m2 K or less, indicating that substantial improvement was gained by directing airflow toward the ceiling. To link the experimental results to an application in a full-size building, an approximate model is presented to estimate the impact of directed night ventilation on the thermal mass (specifically the concrete slab ceiling) and room air temperatures. Coupling angled flow with nighttime ventilation, the ceiling slab and peak daytime air temperature can be reduced by 5 °C compared to horizontal ventilation from a window at conventional height. These results have enabled collaborators in Gujarat, India, to launch tests in a full-scale home serving a low-income community without access to air conditioning.
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DOI of Published Version
https://doi.org/10.3390/buildings16112078
