Mean Radiant Temperature
Also known as: MRT
Air temperature only tells part of the story. Standing in the sun on a hot pavement can feel unbearable even when the air is mild — because the surfaces around you are radiating enormous amounts of heat. Mean radiant temperature captures that radiative load.
Scientific detail
MRT is the uniform surface temperature of an imaginary enclosure that would exchange the same net radiative energy with a human as the actual environment. It is measured with globe thermometers or computed from view-factor-weighted longwave and shortwave fluxes. MRT typically dominates outdoor thermal comfort in the tropics; reflective canopies can drop MRT under-canopy by more than 15 °C at solar noon.
Related terms
Thermal Comfort
The condition in which a person is neither too hot nor too cold.
Wet Bulb Globe Temperature
A composite heat index widely used to set safe limits for outdoor work, sport and military training.
Universal Thermal Climate Index
A modern, physiology-based heat index that estimates how the human body actually responds to weather.
Reflective Canopies
Overhead structures with a reflective upper surface that shade people and land beneath.
Surface Energy Balance
The bookkeeping of energy flowing into and out of a surface at every moment.
Where this concept shows up on MEER
Explore in topic hubs
Curated collections of MEER research, projects, publications and stories that feature this term.
Heat Resilience
MEER's work on heat resilience: physiological modeling with JOS-3, WBGT and UTCI measurement, HeatLens risk assessment, and community projects that protect the most exposed populations.
Urban Heat
The urban heat-island effect, its measurement, and how MEER's reflective roofs, canopies and pavements reduce peak city temperatures and protect vulnerable urban populations.
Measurement & Data
MEER's measurement stack: environmental sensors, physiological modeling (JOS-3), HeatLens risk assessment, and the data that grounds every deployment.