MRTarvoja

MRTarvoja refers to the mean radiant temperature (MRT) values used in building physics and human thermal comfort research. MRT is the uniform temperature of an imaginary surrounding environment that would cause the same amount of radiative heat exchange with a person as the actual nonuniform surroundings. MRT values help describe the radiant heat load a person experiences from surrounding surfaces, objects, and ceilings.

MRT is typically determined from measurements of surface temperatures in the occupied space and the geometry of the surroundings, or by using a black globe thermometer combined with air temperature data. A black globe thermometer captures the combined effect of radiant and convective heat exchange, from which MRT can be calculated or estimated. In practice, MRT is often derived from measurements at occupant level using instruments such as globe thermometers, infrared sensors, or radiometric devices, with consideration of surface emissivity and sky conditions.

MRT is a key component of operative temperature, a composite index used to assess thermal comfort. In still air, the operative temperature can be approximated as the average of air temperature and MRT, Top ≈ (Ta + MRT)/2, while in ventilated spaces the relationship becomes more complex. Higher MRT values indicate greater radiant heat load, while lower MRT values indicate cooler radiant surroundings. MRT thus complements air temperature in understanding occupants’ thermal sensations.

Applications of MRTarvoja include evaluating indoor comfort in offices, schools, and hospitals, guiding design decisions for glazing, shading, and radiant heating or cooling systems, and informing energy-performance assessments. Limitations include sensitivity to measurement placement, surface emissivity, and nonuniform surroundings, which require careful interpretation and, when possible, multiple measurement points across the space.