The Thermodynamics Laboratory of University of Liège comprises different research teams, of which the Energy Systems Research Group (Prof. V. Lemort) is part. The team comprises one assistant professor, one emeritus professor, 8 Ph.D. students (2 of them working in Industry), an average of 2 visiting researchers, 2 technicians, 2 engineers.

Research projects at the Energy Systems Research Group aim at developing innovative thermal systems or improving energy performance of existing systems. Research methodology is based on both numerical and experimental approaches.
Research activities are organized according to three axes:

  1. Heating, ventilation, air-conditioning and refrigeration technologies (HVAC&R) for stationary (residential and commercial buildings) and mobile (automotive, railway and aerospace) applications.
  2. Distributed power production through two main techniques: micro and small-scale combined heat and power (CHP) and heat recovery. Nowadays, research activities focus mainly on the development of the Organic Rankine Cycle technology.
  3. Energy performance of buildings, with a focus on the coupling between HVAC equipments and the building.



In the field of energy performance of buildings, the group is mainly working on the coupling between HVAC systems and building envelopes. The group is involved in different International Energy Agency projects, in the frame of the ECBCS (Energy Conservation in Buildings and Community Systems) programme.

Recent projects deal with the analysis and evaluation methods of energy use in buildings (IEA-ECBCS Annex 53). The group is also developing simulation tools for the energy audit of buildings (in the frame of the European projects IEE-AuditAC and IEE-HarmonAC) and participating in the development of on-line building energy simulation tools dedicated to the design of new residential and tertiary buildings (SISAL 1 and 2 projects). Finally, the team in involved in the national implementation of the EPB directive (EPICOOL projects).

  • Development of simulations HVAC components simulation models for residential and tertiary buildings: SISAL & SISAL 2
  • Development of benchmarking, inspection and audit procedures for air-conditioned buildings: IEE-AUDITAC & IEE-HARMONAC.
  • Development of analysis and evaluation procedures for total energy use in buildings:
  • National implementation of the EPBD calculation method: EPICOOL
  • Participation to "Construire avec l'énergie" programme: CALE


The research activities dealing with HVAC system balances both experimental and numerical approaches. Through years, the Laboratory has gained a strong experience in the testing and the modeling of positive displacement compressors, especially scroll compressors. Other research projects deals with the development of efficient vapor compression heat pumps, chillers and room air-conditioners. The group also investigates other technologies of refrigeration such as the Ericsson cycle.

 Recently, the Laboratory was involved in IEA-ECBCS Annex 43 and Annex 48 projects dealing, respectively, with validation of HVAC&R components simulation models and integration of heat pump systems in tertiary buildings. The laboratory is also carrying out investigation on cool and heat and cold storage (ice storage systems) and distribution (modeling of hydronic networks, radiant ceilings).

Besides stationary air-conditioning or refrigeration systems, the group is developing research activities in the field of mobile air-conditioning (car, railway applications) and refrigeration for telecommunications satellites.

  • Heat recovery and reversible heat pumping in tertiary buildings: IEA-ECBCS Annex 48
  • Development and validation of HVAC components simulation models: IEA-SHC Task 34/ECBCS Annex 43
  • Development of an integrated air-to-air heat recovery system for residential buildings: GREEN+
  • Testing and modeling of refrigeration systems for vehicles.
  • Testing and modeling of air dryers.


The third axis of research deals with the small- and medium scale Rankine cycles. Historically, the laboratory investigated the possibility to use scroll expander for steam cycles. The group was then involved in the development of a prototype of small-scale Organic Rankine Cycle (ORC) system.

Topics of interest for the team became more diverse, going from the selection of the fluids, to the design of the expansion machines and of the pump and more recently to the control of the system. The group is investigating the possibilities to use ORC technologies for recovering heat in industry process (glass, steal), mechanical equipments and internal combustion engines.

Besides small-scale systems, the group is also involved in the development of a larger off-grid ORC system (300 kW) that uses biomass as the heat source.