The SMART sensor: fully characterizing radiant heat transfer in the built environment

Abstract

In a conventional indoor environment, thermal comfort is supplied by an air based distribution system. This system is controlled by an air temperature (and occasionally humidity) sensor, and the role of radiation in thermal comfort is often overlooked. In a typical indoor environment, slightly less than half of the heat occupants shed to maintain thermal comfort is lost to convection. The other portion is lost to radiation. We have developed the Scanning Mean Radiant Temperature (SMART) Sensor to fully characterize radiant heat transfer in the built environment. Combining surface temperatures and geometry allows us to produce 3D thermal point clouds which may be meshed to produce watertight surfaces. The view factor between occupants and environmental surfaces may be calculated, allowing us to accurately model radiative heat transfer. Additionally, this may be calculated for any location in the space, allowing us to map spatial variation of the mean radiant temperature from a single scan. In this paper, we use the SMART sensor to calculate the spatial distribution of mean radiant temperature over a range of environmental conditions. Its performance is validated using a net radiometer. The sensor demonstrates that there is frequently significant spatial variation of mean radiant temperature in typical indoor environments up to 4 °C.