Overview
Background information: Basics of heat transfer and Mean Radiant Temperature (MRT)
There are three ways by which heat can be transferred: conduction, convection, and radiation.
-
Conduction is the movement of energy due to direct contact, like placing a hand against a warm rock.
-
Convective heat transfer occurs due to the movement of a fluid. This is the primary method conventional air conditioners use to control thermal comfort.
-
Radiative heat transfer is the movement of energy via electromagnetic waves emitted by surfaces. When placed in the sun, an object is being warmed by infrared radiation.
At CHAOSense, we focus primarily on the oft-neglected effects of radiative heat transfer. Though modern thermal comfort regulation focuses primarily on convection (air conditioning), radiant heating and cooling plays a profound role in how warm people feel. One key metric is mean radiant temperature (MRT), which quantifies the average radiative effects of an environment on a body.
Measuring MRT:
MRT measurement can be surprisingly difficult, particularly in complex environments. Since their development in the early 1900s, the primary method of MRT measurement has been through the use of devices called globe thermometers. They consist of a thermometer placed inside of a black globe. The concept is that the globe absorbs the radiant energy from the surrounding environment, so comparing the internal temperature to ambient yields the heat transfer due to radiation. While this works in theory, recent studies