Radiant cooling systems coupled with active air movement

In the context of global warming, it is important to find solutions to decrease emission of greenhouse gases. It becomes clear that reducing energy consumption will be a big part of this challenge. The operation of buildings (heating, cooling and lighting) leads to approximately 28% of world CO2 emissions [UNEP & IEA, 2017]. Furthermore, the cooling sector is rapidly growing, tripling its CO2 emissions from 1990 to 2018 [IEA, 2019] even though cooling technologies are getting more efficient. Radical new approaches must be explored to slow and even reverse this alarming increase. However, while developing a technology or approach, a special care on comfort of people in building must be taken, otherwise there is a high probability that these new approaches will never be widely adopted. This master thesis joins an ongoing research project done by the CBE from UC Berkeley (USA) in collaboration with the radiant panel Japanese company SANKEN. The overall goal of this CBE-Sanken research study is to develop design guidance for a combined system consisting of cooling radiant ceiling panels and fan-induced elevated air movement. In this context, a large number of experiments were done in the twin chambers of the Thermal Façade Lab at University of Texas School of Architecture in Austin (USA) involving a reversible ceiling fan and three different cooling systems : all-air system and two types of ceiling radiant panels (classic sheet metal radiant panels abbreviated UT panels and Sanken radiant panels with gaps that enhance convection). This master thesis comes in complement of the CBE-Sanken research study. These combinations of systems can create significant heterogeneities in space and have not been extensively studied. This study aims to understand the space heterogeneities, created by those complex systems, from a human perspective. More precisely, in this master thesis, the following combinations of cooling systems are studied: • All-air cooling + Ventilation • All-air cooling + Ventilation + Fan (blowing upward vs downward) • Radiant cooling + Ventilation • Radiant cooling + Ventilation + Fan (blowing upward vs downward) To reduce the number of experiments and because this study aims to be general, only the radiant cooling done with conventional radiant panels (UT panels) will be studied, excluding the Sanken panel experiments. The first part of this report is devoted to the description of the experiments done, the processing of the results and the description of the heterogeneities of the thermal environment. The second part presents how the Mean Radiant Temperature was modeled through the ray-tracing technique, a technique originally used in computer graphics and adapted to heat transfer estimation for this work. The last part answers to the question of the human perspective through a thermal comfort study and tries to link the variations in the physical environment to the different thermal comfort responses.