Cooling capacity evaluation of thermally activated light shelf (TALS) systems

Abstract

A light shelf is typically used to improve the lighting environment by preventing glares and increasing illuminance in interior zones. If its surfaces can be utilized as cooling surfaces it can also be used to control the thermal environment, particularly in perimeter zones. In this study, the concept of a thermally activated light shelf (TALS), wherein a chilled water pipe is embedded in a light shelf, was proposed, and its cooling capacity was experimentally evaluated. As the upper and lower surfaces are exposed to indoor air and cooling loads, which are different from those of conventional radiant cooling panels, a mock-up test chamber was developed to represent the cooling load applied to both the upper and lower surfaces of the TALS. Mock-up experiments were conducted to evaluate the cooling capacity of the TALS alternatives: TALS with thermal insulation (INS case), cavity air (AIR case), and DC fans (FAN case). Compared with the baseline (INS case), the cooling capacities of the AIR and FAN cases were enhanced by 9.4–29.4% and 22.7–53.1%, respectively, because both the upper and lower surfaces could be utilized as cooling surfaces. Based on the experimental results, cooling capacity curves were derived to provide generalized cooling capacity data considering various cooling load conditions, operating conditions (e.g., chilled water temperature and room air temperature), and layer configurations of the TALS.