Performance evaluations of high-temperature cooling systems in Mediterranean climate
Time: Thu 2021-02-25 13.00
Location: Stockholm (English)
Subject area: Civil and Architectural Engineering, Fluid and Climate Theory
Doctoral student: Henrikki Pieskä , Hållbara byggnader
Opponent: Docent Saqib Javed, Lunds Universitet
Supervisor: Associate Professor Christophe Duwig, Linné Flow Center, FLOW, SeRC - Swedish e-Science Research Centre, Processteknologi
Cooling demand in Europe is predicted to grow 25-50% between 2020-2050. Meanwhile, the EU aims to lower the greenhouse gas emissions from its building stock by 60%. Therefore, it is essential to find solutions that can meet the growing cooling demand with less energy and integrate renewable energy sources. The goal of this thesis is to technically evaluatehigh-temperature cooling systems and their contributions to the targets mentioned above. The study was conducted using advanced building energy simulations and developing analytical methods. IDA Indoor Climate and Energy 4.8was selected as the simulation tool. The study is a part of GEOFIT project, and the used building physics and measurement data were based on one of the project pilots. The selected building is a representative office building that is a part of a three-building school complex. The building is located in Sant Cugat near Barcelona, in an area which has a typical Mediterranean climate. The simulated building model was validated using onsite measurement data. Two types of high-temperature cooling systems were studied: a radiant cooling system and an all-air cooling system. For the study, the systems were designed to create equal thermal comfort conditions, so that their energy and exergy use could be compared. In the studied case, the radiant cooling system was found to use 40% less energy and consume 85% less exergy than a conventional low-temperature all-air cooling system. It was also found that a passive geothermal radiant cooling system requires 66% less electricity for pumps and fans than a passive geothermal all-air cooling system. The results demonstrate that radiant cooling systems have the potential to lower exergy consumption in cooling applications thanks to the high supply temperature and that using water as a heat transfer medium is more efficient than using air.