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. / Kylningsefterfrågan i Europa förutses att växa 25-50% mellan 2020-2050. Samtidigt strävar EU efter att sänka utsläppen av växthusgaser från sina byggnader med 60%. Det är därför viktigt att hitta lösningar som kan tillgodose det växande kylbehovet med mindre energi och att integrera förnybara energikällor. Målet med denna avhandling är en teknisk evaluering av högtemperatur-kylsystem och deras bidrag till ovan nämnda mål. Studien genomfördes med avancerade simuleringar av byggnadsenergi och utvecklade analytiska metoder. IDA Indoor Climate and Energy 4.8 valdes som simuleringsverktyg. Studien är en del av GEOFIT-projektet och den använda byggnadsfysiken och mätdata baserades på en av projektpiloterna. Den valda byggnaden är en representativ kontorsbyggnad som ingår i ett skolbyggnad med tre byggnader. Byggnaden ligger i Sant Cugat nära Barcelona, i ett område som har ett typiskt medelhavsklimat. Den simulerade byggnadsmodellen validerades med hjälp av mätdata på plats. Två typer av högtemperatur-kylsystem studerades: ett strålande kylsystem och ett luftkylsystem. För studien designades systemen för att skapa lika termiska komfortförhållanden, så att deras energi och exergianvändning kunde jämföras. I det studerade fallet visade sig att det strålande kylsystemet använde 40% mindre energi och förbrukade 85% mindre exergi än ett konventionellt högtemperatur-kylsystem med låg temperatur. Man fann också att ett passivt geotermiskt strålkylsystem kräver 66% mindre el för pumpar och fläktar än ett passivt geotermiskt luftkylsystem. Resultaten visar att strålningskylsystem har potential att sänka exergiförbrukningen i kylapplikationer tack vare den höga framledningstemperaturen och att användning av vatten som värmeöverföringsmedium är effektivare än att använda luft. / <p>QC 210204</p>

High Temperature Cooling, HTC, is a thermal conditioning strategy, which aims to reducemixing and transfer heat losses. Cooling capacity strongly depends on heat transfer coefficientsand offers a great response and several advantages in terms of efficiency and sustainability.Among the advantages, there is evidence that HTC offers an increment of energy efficiency ofHVAC systems, provision of healthier and more comfortable indoor climate and provide widepotentials for the applications of renewable. This principle leads to a higher energy efficiency ofwater-based radiant cooling systems.This paper intends to focus on the research of the thermal capacity and performance of a newalternative. This is where Cooling Radiant Ceiling Panels, CRCP, becomes a major innovationwithin the sector and begin to take on certain relevance. The cooling capacity curve of thisparticular CRCP panels has been only measured in an idealized room environment according toDIN EN 14240. Thus, further studies of this key parameter through climate chamber testingand Computational Fluid Dynamics simulations, CFD, are necessary. CFD particularly focuseson fluids in motion, their behavior and their influences in complex processes such as heat transfer.The fluid motion can be described through fundamental mathematical equations and it isbecoming widely used within the building sector.Two different cases are going to be investigated. The first case will determine the mostoptimal peripheral gap to enhance cooling performance through Natural Convection, NC. Thisstudy states the existence of a peripheral gap around the panels has proven to be inefficientin terms of enhancing natural convection in the climate chamber. The second case is aboutcalculating the cooling capacity as a function of the internal heat loads. The cooling capacity ofthe CRCP panels followed an expected behavior. The R-squared factor of the linear regressionwas found to be 0.986, hence, it does not affect the performance of the CRCP panels dependingon the inclusion of the IHLs.This thesis provides the necessary information for the implementation of CRCP panels anddifferent possible operating environments, including considerations, limitations and recommendationsfor future implementation of this strategy.