Human response to the thermal indoor environment created by a radiant, and a combined radiant and convective cooling system

Abstract

This study reports the main findings from a series of human subject experiments, where the subjects were exposed to the different indoor environments created by different cooling systems. The studied systems were a radiant cooling system (chilled ceiling and mixing ventilation, CCMV), and a combined radiant and convective cooling system (radiant diffuse ceiling ventilation, RDCV). The experiments were conducted in a climate chamber under controlled conditions. The climate chamber was configured as a two-person office room. 24 human subjects (12 female and 12 male) were chosen. The exposure lasted three hours and the participants were allowed to work on their own tasks (normal office work) during the exposure. The cooling load was 54 W/m2 and the room temperature at a reference location was kept constant at 26°C (summer conditions). The results show that under both systems, whole body thermal sensation was between slightly warm and neutral (closer to neutral with the RDCV system), and the overall thermal acceptability was almost the same for both systems (close to clearly acceptable). The satisfaction of the human subjects with the thermal environment was very close under the two systems; between satisfactory and slightly satisfactory (closer to satisfactory). Air movement acceptability (slightly higher and closer to clearly acceptable with the RDCV system) was also very close with the two systems. The results of the human subject experiments agree well with the physical measurements of the thermal indoor environment and confirm that the studied systems created very similar thermal indoor environments.

Experimental comparison of thermal conditions in office rooms: Diffuse ceiling ventilation, chilled beam system, and chilled ceiling combined with mixing ventilation

“…A recent study shows that the cooling capacity of radiant ceiling can be enhanced by conducting a distributed panel layout instead of a centralized layout (Shin et al 2019). Moreover, a radiant ceiling cooling may compensate the presence of warm surfaces in the chamber, resulting similar indoor air and operative temperatures (Kazanci et al 2018;Jia et al 2018). In addition, the air velocity around the panel surface impact on the cooling performance (Tian et al 2012).…”

Differences in temperature measurement by commercial room temperature sensors: Effects of room cooling system, loads, sensor type and position

“…The radiant and all-air systems were each tested for low and high cooling loads, resulting in four test conditions. System operations and load conditions were set as closely as possible to previous experiments by Mustakallio et al [32,33] and Kazanci et al [34]. For each of the four conditions, the reference and selected sensors were moved to seven different positions, as shown in Fig.…”

“…Table 2 shows the cooling load components. Two conditions were set for the cooling load, low (usual) and high (design) loads, in accordance with previous experiments conducted in the same climate chamber by Mustakallio et al [32,33] and Kazanci et al [34], using the same load inputs. For both the low and high load cases, two dummies simulating occupants, two laptops and four suspended lighting units were used.…”

“…The dummies were made of metal cylinders (without any openings) with electric heating cables wrapped in the inside. The cooling load from the lighting units was 168 W throughout the experiment, as in previous measurements [34]. The laptop computers were connected to power at all times, and the screensaver and sleep modes were disabled to prevent a change in the generated heat during the experiment.…”

Comparison of Thermal Sensations Under the Same Conditions in the Climatic Chamber and the Lecture Hall

“…However, studies in the climatic chamber were conducted by Kazanci et al [8]. The chamber has been divided into two rooms in office conditions.…”