Jessen joined the University of Applied Arts and Sciences of Western Switzerland (HES-SO) as a professor for Energy Systems in May 2013. He shares his time between courses given to bachelor and master students of the HES-SO and the research he leads in the development and implementation of urban energy concepts and the transformation of today's cities into the Smart Cities of tomorrow.
Prior to working at HES-SO Jessen worked for three years at the Austrian Institute of Technology where he lead a small team of researchers devoted to the study and simulation of energy within the urban context, in particular in the development of tools that can assist decision-makers in designing the low carbon cities of tomorrow. From 2007 till 2010 he performed as a sustainability and later senior energy consultant at the head office of Arup, an engineering consultancy, in London. This experience provided him with a great deal of insight into sustainable urban design and the necessity to adopt an approach that integrates the various strategies involved (water, transport, energy, socio-economics, logistics, waste, etc.).
Jessen holds a doctorate of science from the Ecole Polytechnique Fédérale de Lausanne, where he developed stochastic models to simulate the impact of occupant behavior on buildings' energy demands, as well as a masters in physics from the University of Fribourg.