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Abstract The globe thermometer has been considered a reliable instrument to quantify mean radiant temperature (MRT) since Bedford & Warner isolated its readings from air movement in their 1934 paper so that radiation could be quantified. Recent expanded use of radiant heating and cooling systems has presented new challenges for the usage of globe thermometers in the built environment by causing additional radiant asymmetries and performance expectations. Therefore, we replicate the original Bedford & Warner work to reconsider and develop a more holistic understanding of black globe performance and the determination of MRT in buildings. We recreate the MRT and air temperature separation to investigate the accuracy of globe thermometers on measuring MRTs. A radiantly heated open-plan laboratory and a radiantly cooled conference room were selected and measured with multiple globe thermometers and non-contacting infrared sensors. The globe temperature results were then corrected with air movement to produce MRTs and compared against MRTs simulated from measured surface temperatures. We demonstrate a significant impact of air speed on the MRTs obtained from globe thermometers. We also illustrate a less-investigated non-graybody emissivity variation and spatial variation of MRTs of up to 5 °C at the same height. We believe the increasing temporal and spatial resolution of digital sensors may create new challenges for using globe thermometers to measure MRTs, since fluctuating readings may camouflage potential MRT changes. Through a validation of our spatial MRT distribution with experimental results, we believe there is a need for better sensors that could spatially resolve MRTs, and recognize issues with both air speed and emissivity. [ABSTRACT FROM AUTHOR]

Mean radiant temperature is central to our understanding of the radiant heat exchange between the human body and surrounding environment. This paper will present a review of the concept's evolution including its qualitative definition, methods of quantitative evaluation and corresponding challenges. In the process, this review suggests that more effort needs to be invested in addressing the geometric complexities of radiant heat transfer in research into MRT; the ASHRAE definition is broad and is liable to simplification, and research which uses the definition relies on a variety of simplifications, often without acknowledging the degree of geometric complexity which exists in reality. Existing means of obtaining an estimate of mean radiant temperature range from direct measurements using globe thermometers or net radiometers, to computational simulations, and are widely used for studies within indoor and outdoor environments. Previous literature studying the correlation between air temperature and MRT has found equivalence ratios, the relative importance of convection to radiation, ranging from 0.71 to 1.4, however, it is often assumed to be 1.0 in current research practices. We also identified a rapid increase in the usage of MRT in biometeorological studies during the last ten years on top of the increased usage in indoor environment sensing and modeling in light of recent developments in heating and cooling systems. Recent efforts to include the short-wave component in indoor MRT characterization have shown an increase in cooling capacity of radiant floors from 32 to 110 W/m2; significantly decreasing peak energy demand. • We have expanded the conclusion section with both numerical conclusions and expanded discussions on the limitations of existing MRT usages. • Included new citations that covers the latest development of MRT research and standardization effort (ASHRAE Standard 55-2017, for example). • Adding new illustration of the MRT as a concept in relation to the human body geometry. • Expanded review on how indoor MRT variations due to shortwave radiation are characterized [ABSTRACT FROM AUTHOR]