The energy transition group has a research agenda focused on the development of sustainable and systemic solutions to the energy transition. The foundations for the energy transition are generation of renewable and clean energy and its efficient and well managed used. We target both challenges, with focus on:

  1. Solar energy, from materials for energy to resource assessment and forecasting, distributed generation, system integration with electric vehicles and long term renewable energy scenarios;
  2. Energy in buildings, including theoretical  and experimental approaches to natural ventilation and building stock energy modelling, applied research and design projects as well as building energy audits;
  3. System energy and emission analysis including mass and energy flow balances of systems transportation and biorefinery systems

Scientific Highlights 2019


To increase the penetration of photovoltaic renewable energy (PV RE) in the residential building sector energy mix, the mismatch between mid-day production and evening electrical energy demand must be bridged. The use of heat pumps for space heating of residential buildings creates an opportunity for energy flexible residential buildings that rely on low-cost thermal energy storage systems. This paper explores the ‘building as battery’ concept (BaB), i.e. the use of the structural thermal capacity as a heat storage medium in winter. In these systems the building internal mass is preheated during solar daytime hours (using a PV RE powered heat pump) and cooled by discharge into the room air after sunset, for space heating. This study presents measured and simulated performance of BaB systems used for thermal energy storage in living rooms of three different apartment buildings with variable thermal insulation levels, ranging from typical southern Europe 1980s construction to an insulated apartment (Passive House certified). The results show that, for apartments with high thermal mass, thermal insulation is the key driver of BaB system thermal efficiency, with the highly insulated apartment reaching BaB efficiencies of 60–80%. For existing apartments with a low thermal insulation, the BaB approach is only effective when space heating is required right after sunset (just when PV RE powered heat pump charging finishes).

The decarbonization of the energy system is based on the increasing penetration of renewable energies in the electric system. The time variability of these resources requires the widespread use of energy storage solutions. Supercapacitors are particularly attractive for applications requiring relatively high power and low energy as well as fast and frequent charge/discharge cycles.
Another critical step for renewable generation is the fact that the growing deployment of photovoltaic (PV) systems requires the development of simple and efficient methods to survey the performance of PV devices and detect failures. The use of luminesce based methods to detect faults in all steps of the device production and use has gained a crucial importance for the photovoltaic community.

Group Leader


Grant Researcher

PhD Students

External Collaborator

  • Sara Freitas