Joachim Claesson

I am Associate Professor in Energy Technology at KTH Royal Institute of Technology, where my research focuses on energy systems in buildings, heat pumps, geothermal energy, thermal comfort, ventilation, heat recovery, and sustainable energy utilization. Throughout my academic career, I have worked across scales ranging from heat transfer phenomena in individual components to the performance and interaction of complete building energy systems.

My doctoral research focused on the thermal and hydraulic performance of compact braed plate heat exchangers operating as evaporators in heat pump systems. This work combined experimental and theoretical studies of refrigerant evaporation, heat transfer, pressure drop, and component design, contributing to a better understanding of heat pump performance and refrigeration technology.

Over the years, my research has gradually expanded from component-level studies to itegrated energy systems for buildings. A major area of my work has been the development and evaluation of ground source heat pump systems, including capacity-controlled heat pumps, borehole thermal energy storage, and the interaction between neighbouring boreholes in densely populated urban areas. I was the principal investigator of projects leading to new methods and design tools for evaluating thermal interference between geothermal installations and improving the design of ground source heat pump systems in urban environments. These projects resulted in several peer-reviewed publications and the supervision of a completed Ph.D. project.

I have also conducted extensive research on building energy efficiency and heat recoery technologies, including ventilation heat recovery, wastewater heat recovery, and innovative heat pump-assisted recovery systems. Several projects have focused on practical solutions that can be implemented in existing buildings, with the objective of reducing energy demand while maintaining or improving indoor environmental quality and occupant comfort. 

Another research theme has been the development of innovative heating technologies. have been principal investigator for projects concerning novel heat pump concepts for residential buildings, including systems combining multiple heat sources and solutions aimed at increasing both energy and power efficiency while improving operational reliability. These projects have been funded by the Swedish Energy Agency and carried out in close collaboration with industry partners.

More recently, my research interests have expanded to include thermal comfort, indoo environmental quality, water systems in buildings, and electrified transportation. I am currently principal investigator of the project ElBussTransTherm – Energy Efficiency in Electric Road Public Transit, funded by the Swedish Energy Agency. The project investigates how thermal comfort and HVAC operation in electric buses can be improved while simultaneously reducing energy consumption and increasing operational efficiency. The work combines measurements, modelling, system analysis, and passenger comfort assessments, with the ultimate goal of extending vehicle range and improving the passenger experience in public transportation.

Throughout my career, I have sought to maintain a strong connection between academicresearch and practical implementation. Many of my projects have been carried out in collaboration with industry, public authorities, and building owners, including partners such as SAAB, Electrolux, Thermia, Nibe, Munters, SWEP, Säker Vatten, and regional public organizations. The common theme has been the development of robust, practical, and energy-efficient solutions that can contribute to the transition towards a more sustainable built environment.

In addition to my research activities, I have supervised doctoral students, master'sstudents, and industrial projects, authored textbooks used in KTH education, and served as Program Director for the doctoral programme in Energy and Environmental Systems. My ambition is to continue developing knowledge and engineering solutions that bridge the gap between fundamental thermal sciences and practical applications in buildings, energy systems, and sustainable transport.