Which metric is commonly used to assess heat stress in tropical environments?

• A. WBGT
• B. PMV/PPD
• C. Envelope air leakage
• D. Daylight metrics

Answer: (C)

Assessing heat stress in tropical environments is best done with a measure that brings together air temperature, humidity, and radiant heat. That measure is Wet-Bulb Globe Temperature, or WBGT. It combines three practical signals: the natural wet-bulb temperature, which reflects evaporative cooling and humidity; the globe temperature, which captures radiant heat from the sun and surroundings; and the dry-bulb air temperature. Together, they give a single index that reflects the overall heat stress risk workers or occupants would experience outdoors or in hot interiors.

WBGT is widely used to guide safety decisions like when to pause work, shorten shifts, provide shade, increase hydration, or deploy cooling strategies. In contrast, PMV/PPD focus on thermal comfort for indoor environments rather than heat stress risk under outdoor or hot-humid conditions. Envelope air leakage relates to how much conditioned air escapes through the building envelope—important for energy and indoor air quality, not directly for assessing heat stress. Daylight metrics evaluate lighting performance, not thermal stress.

So the metric commonly used to assess heat stress in tropical environments is WBGT.