1. E. Syngounas, D. Tsimpoukis, M. Koukou, M. Vrachopoulos, Greenhouse heating and cooling performance assessment using a novel CO2 ground-source heat-pump, Int. Conference Energy MAterials and NATural rEsources 2023 (EMANATE 2023), May11–12, 2023 Chalkida, Greece.
   https://conferences.uoa.gr/event/68/attachments/172/530/Book%20of%20Abstracts%20EMANATE.pdf
    
2. A. Zarkadoulas, J. Konstantaras, V. Stathopoulos, M. Koukou, M. Vrachopoulos, Functional coatings for smooth operation and stable performance of flat-type solar panels under various conditions, Int. Conference Energy MAterials and NATural rEsources 2023 (EMANATE 2023), May11–12, 2023 Chalkida, Greece.
   https://conferences.uoa.gr/event/68/attachments/172/530/Book%20of%20Abstracts%20EMANATE.pdf
    
3. D. Pomoni, I. Konstantaras, M.K. Koukou, M.Gr. Vrachopoulos, Circular Economy: From concept to implementation, agri-food oriented, Int. Conference Energy MAterials and NATural rEsources 2023 (EMANATE 2023), May11–12, 2023 Chalkida, Greece.
   https://conferences.uoa.gr/event/68/attachments/172/530/Book%20of%20Abstracts%20EMANATE.pdf
    
4. G. Evangelakis, C. Prouskas, J. Konstantaras, K. Lymperis, M. Koukou, M. Vrachopoulos, Towards Nanofluids with excellent light radiation absorption, Int. Conference Energy MAterials and NATural rEsources 2023 (EMANATE 2023), May11–12, 2023 Chalkida, Greece.
   https://conferences.uoa.gr/event/68/attachments/172/530/Book%20of%20Abstracts%20EMANATE.pdf
    
5. C.C. Spandonidis, P. Theodoropoulos, E.G. Pariotis, T.C. Zannis, S. Polyzos, K. Alexiou, J. Konstantaras, M.K. Koukou, M.Gr. Vrachopoulos, Meta-data analysis, prospects, challenges, and a roadmap for optimal ship energy management using a digital twin, 19th International Congress of the International Maritime Association of the Mediterranean, IMAM 2022, Instabul, Turkey, 26-29 September 2022, Proceedings in: Sustainable Development and Innovations in Marine Technologies: Pages 93-99, Publisher CRC Press.
   https://doi.org/10.1201/9781003358961
    
6. Maria K. Koukou, John Konstantaras, George Dogkas, Kostas Lymperis, Vassilis N. Stathopoulos, Michail Gr. Vrachopoulos, Eleni Douvi, Yannis Caouris, Petros Dimas, Development of a novel compact flat-plate solar collector integrated with thermal energy storage: experimental evaluation of the energy stored under outdoors conditions, Proceedings of the 13th International Conference on Sustainable Energy & Environmental Protection (SEEP), University of Natural Resources and Life Science, Vienna 13th - 16th September 2021
    
7. Ch. Pagkalos, St. Markolefas, M. Koukou, E. Douvi, J. Konstantaras, G. Dogkas, Y. Caouris, M. Vrachopoulos "Development of a Novel Compact Flat Plate Solar Collector Integrated with LHTES Tank: Finite Element Analysis to Evaluate Optimum Tank Insulation and Structural Analysis of the Supporting Base", 8th International Conference on "Energy, Sustainability and Climate Crisis", ESCC 2021, Volos, Greece, August 30 - September 3, 2021
   http://escc.uth.gr/escc-series/escc-2021/
    
8. Evangelos Syngounas, Dimitrios Tsimpoukis, Stavros D. Anagnostatos, Maria K. Koukou, Michail Gr. Vrachopoulos, Energetic and financial evaluation of a solar-powered absorption chiller integration into a CO2 commercial refrigeration system, ECRES: 9^th European Conference on Renewable Energy Systems, 21-23th April, Instabul, Turkey (2021)
    
9. L. Coelho, A. Rebola, João Pássaro, M. K. Koukou, M.Gr. Vrachopoulos, K. Karytsas; A. Benou, H Gaich, G. Evangelakis, T. Bakon, P. Tourou, A. Esquerra Alsius, A. Dicken, Z. Chrysanthou, Thermal Energy Storage: an overview of one advanced system based on the European Tesse2b project, oral presentation at International Conference Energy in Buildings 2019, organized by ASHRAE Greek Chapter 28.09.2019, Athens. Link at:
   https://www.ashrae.gr//Proceedings//EinB2019_Proceedings.pdf
    
10. P. Tourou, I. Konstantaras, M.Gr. Vrachopoulos, C. Sourkounis, M.K. Koukou, C. Pagkalos, K. Lymperis, G. Dogkas, Validation of a control algorithm for the efficient charging of PCM energy storage tanks using an emulation platform, oral presentation at International Conference Energy in Buildings 2019, organized by ASHRAE Greek Chapter 28.09.2019, Athens. Link at:
    https://www.ashrae.gr//Proceedings//EinB2019_Proceedings.pdf
     
11. C. Pagkalos, M.K. Koukou, M.Gr. Vrachopoulos, J. Konstantaras, G. Dogkas, K. Lymperis, Design of thermoplastic tanks for thermal energy storage applications using Finite Element Analysis, poster at International Conference Energy in Buildings 2019, organized by ASHRAE Greek Chapter 28.09.2019, Athens. Link at: https://www.ashrae.gr//Proceedings//EinB2019_Proceedings.pdf
     
12. M.K. Koukou, M.Gr. Vrachopoulos, G. Dogkas, C. Pagkalos, K. Lymperis, L. Coelho, and A. Rebola, Testing the performance of a prototype thermal energy storage tank working with organic phase change material for space heating application conditions, poster at International Conference on Advances in Energy Systems and Environmental Engineering (ASEE19), Wroclaw, Poland, 09-12.06.2019. Available at:
    ttps://doi.org/10.1051/e3sconf/201911600038
     
13. G. Dogkas, J. Konstantaras, M.K. Koukou, V.N. Stathopoulos, L. Coelho, and A. Rebola Evaluating a Prototype Compact Thermal Energy Storage Tank Using Paraffin-based Phase Change Material for Domestic Hot Water Production, poster at International Conference on Advances in Energy Systems and Environmental Engineering (ASEE19), Wroclaw, Poland, 09-12.06.2019. Available at:
    https://doi.org/10.1051/e3sconf/201911600016
     
14. M.K. Koukou, M.Gr. Vrachopoulos, G. Dogkas, C. Pagkalos, J. Konstantaras, K. Lymperis, and V. Stathopoulos, Study of Heat Transfer in a Latent Heat Storage System using Salt Hydrates for Domestic Heating Applications, oral presentation at Energy in Buildings 2018, organized by ASHRAE Greek Chapter, 3rd November, Athens, Greece, 2018. Available at: https://www.ashrae.gr//Proceedings//EinB2018_PROCEEDINGS.pdf
     
15. M.Gr. Vrachopoulos, M.K. Koukou, G. Dogkas, N. Tachos, Experimental Performance Evaluation of a Small-Scale ORC Power Unit Working with Low Temperature Energy Sources for Power Co-generation, oral presentation at Energy in Buildings 2018, organized by ASHRAE Greek Chapter, 3rd November, Athens, Greece, 2018. Available at: https://www.ashrae.gr//Proceedings//EinB2018_PROCEEDINGS.pdf
     
16. P.K. Pandis, S. Papaioannou, M. Koukou, M. Vrachopoulos, V.N. Stathopoulos, Differential scanning calorimetry-based evaluation of 3D printed PLA for phase change materials encapsulation or as container material of heat storage tanks, 2^nd International Conference on Sustainable Energy and Resource Use in Food Chains ICSEF 2018, international workshop on Energy Recovery Conversion and Management ERCoM 2018, Cyprus 17-19.10.2018
     
17. Nikolas P. Tsolakoglou, Maria K. Koukou , Michalis Gr. Vrachopoulos, Nikolaos Tachos, Kostas Lymberis, and Vassilis Stathopoulos, Experimental process investigation of a latent heat energy storage system with a staggered heat exchanger with different phase change materials for solar thermal energy storage applications, 1^st International Conference on Advances in Energy Systems and Environmental Engineering (ASEE17), July 2-5, Wroclaw, Poland, 2017. Available at: https://doi.org/10.1051/e3sconf/20172200179
     
18. V. Chalkia, N. Tachos, A. Giannakas, M. Koukou, A. Ladavos, M. Vrachopoulos, V. Stathopoulos, Effect of organic phase change materials in the physicochemical properties of thermoplastic polymers, poster presented in 22^nd Conference of Chemistry, December 2-4, Thessaloniki, Greece, 2016
     
19. M. Gr. Vrachopoulos, N. S. Tachos, M. K. Koukou, G. K. Karanasiou, C. Karytsas, Efficient Organic Rankine Cycle (ORC) Power Generation with low grade energy as heat source: preliminary design of Effi low res ORC unit, 13^th International Conference on Heat Transfer, Thermal Engineering and Environment, Salerno, Italy, June 27-29, 2015
     
20. M.Gr. Vrachopoulos, M.K. Koukou, N. Tachos, S. Kalognomos, A. Adamidis, F. Lavrenti, J. Pappas, P. Xygogianni, C.Karytsas, “Implementing the GEOPEAK Project in Greece towards the achievement of Europe 20-20-20targets:  Development and Evaluation of a Geothermal Heat Pump of High Efficiency” ICERE2014, International Conference on Environment and Renewable Energy, Paris 07-08/05/2014
     
21. Thanos G., Vrachopoulos M.Gr., Koukou M.K., Kakouris A.P., and Thanos A.G., Residence site selection in urban and rural environments in Greece: a multiple-criteria decision analysis approach, 9th Special Conference of HELORS on “Quantitative Models in the Managerial and Financial Decision Making” Agios Nikolaos, Crete, Greece 27-29/05/2010
     
22. Vrachopoulos, M.Gr. and M.K. Koukou, “Definition of horizontal geothermal heat exchanger behaviour”, 9th National Conference on Renewable Energy Sources, (organised by Institute of Solar Technology), 26-28/3/09, Pafos-Geroskipou, 2009
     
23. Vrachopoulos, M.Gr., M.K. Koukou, D. G. Stavlas, V. Stamatopoulos & A.G. Gonidis, “Energy storage in phase change materials (PCMs) – Measurement of thermophysical properties and evaluation of a PCM passive application”, 9th National Conference on Renewable Energy Sources, (organised by Institute of Solar Technology), Cyprus, 26-28/3/09, Pafos-Geroskipou, 2009
     
24. Vrachopoulos, M.Gr., M.K. Koukou, D. G. Stavlas, V. Stamatopoulos & A.G. Gonidis, “Evaluation of reflective insulation application in a prototype chamber in Greece: Experimental results for summer and winter periods”, 9th National Conference on Renewable Energy Sources, (organised by Institute of Solar Technology), Cyprus, 26-28/3/09, Pafos-Geroskipou, 2009
     
25. Stavlas, D.G., Kravvaritis, L.D., Stamatopoulos, V., Vrachopoulos, M.Gr., Koukou M.K. and A.F. Gonidis, Evaluating the effectiveness of a prototype PCM chamber: An experimental and numerical approach, ECOS 2008, 21^st International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, 24–27 June, 2008, Poland
     
26. Vrachopoulos, M.Gr., Stavlas, D.G., Kravvaritis, L.D., Koukou, M.K., Vlachakis, N.W., Orfanoudakis, N.W., Mavromatis S.A., Gonidis, A.G., Performance testing of reflective insulation applied in a prototype experimental chamber in Greece: experimental results for summer and winter period, Heat Transfer 2008, 10^th International Conference on Advanced Computational Methods and Experimental Measurements in Heat Transfer, 9 - 11 July, 2008, Maribor, Slovenia
     
27. Stavrakakis G., Koukou, M.K., Vrachopoulos, M.Gr., and Markatos N.C., Experimental and Numerical Analysis of Natural Ventilation in Buildings, 6^th GRACM International Congress on Computational Mechanics, Thessaloniki, Greece, 19-21 June 2008
     
28. Stavrakakis G., Markatos N.C., Koukou, M.K., Vrachopoulos, M.Gr., Study of airflow pattern and thermal environment in naturally ventilated buildings, ENERTECH 2007, 2^nd International Conference on Renewable Energy Sources and Energy Efficiency, Athens, 18-21 October, (2007)
     
29. Βραχόπουλος, Μ.Γρ., Κραββαρίτης, Ε., Κούκου, Μ.Κ., Σταυλάς, Δ., Σταματόπουλος, Γονίδης, Α., Αξιολόγηση της δυνατότητας ενεργειακής αποθήκευσης υλικών αλλαγής φάσης (PCMs), 2^ο Τακτικό Εθνικό Συνέδριο Μετρολογίας, Αθήνα, 19-20 Οκτωβρίου, (2007). Link:
    https://www.certh.gr/81C920FA.el.aspx
     
30. Γ. Σταυρακάκης, Ν.Χ. Μαρκάτος, Μ.Κ. Κούκου και Μ.Γρ. Βραχόπουλος, Ανάπτυξη Μαθηματικού Μοντέλου Προσομοίωσης Ροής Αέρα στο Εσωτερικό Φυσικά Αεριζόμενου Χώρου, poster, 6^ο Πανελλήνιο Επιστημονικό Συνέδριο Χημικής Μηχανικής, Αθήνα, 31 Μαϊου-2 Ιουνίου,  (2007)
     
31. Α. Τάτσης, Π. Ζέρβας, Χ. Σαρίμβεης, Μ.Κ. Κούκου, και Ν.Χ. Μαρκάτος, Ανάπτυξη ενός Ολοκληρωμένου Υπολογιστικού Εργαλείου για την Αριστοποίηση της Λειτουργίας Κελιών Καυσίμου τύπου PAFC, 6^ο Πανελλήνιο Επιστημονικό Συνέδριο Χημικής Μηχανικής, Αθήνα, 31 Μαϊου-2 Ιουνίου,  (2007)
     
32. Thanos G., Vrachopoulos M.Gr., Kakouris A.P., Koukou M.K., Thanos A.G., A Decision Support System for the Ecological Selection Facility Location: A Multi-criteria Approach, IRMA 2007 International Conference, May 19-23, 2007, Vancouver, Canada. Available at:
    https://www.irma-international.org/proceeding-paper/decision-support-system-ecological-selection/33157/
     
33. Hatziapostolou, A., N. G. Orfanoudakis, M. K. Koukou, G. Raptis, CFD Modeling of the Flow Field inside a Furnace Produced by a Laboratory-Scale Combustor, European Combustion Meeting, ECM, Crete, April 11-13, (2007)
     
34. Hatziapostolou, A., N. G. Orfanoudakis, M. K. Koukou, G. Raptis, CFD modeling of the swirl-stabilised flame produced by a laboratory-scale combustor: selection of the turbulence model, 4^th WSEAS Int. Conf. on Heat Transfer, Thermal Engineering and Environment, Elounda, Agios Nikolaos, Crete Island, Greece, August 21-23, (2006). Available at: http://www.wseas.us/e-library/conferences/2006elounda2/papers/538-301.pdf
     
35. Vrachopoulos, M.Gr., M.K. Koukou, G. Kotsiovelos, E. Kravvaritis, P. Ioannidou, Experimental evaluation of the performance of reflective insulation for improvement of indoor thermal environmental conditions, Int. Conference on Energy and Environmental Systems ‘06, Chalkida, Evia, 8-10 May, (2006). Available at:
    http://www.wseas.us/e-library/conferences/2006evia/papers/516-366.pdf
     
36. Bacharoudis, E., Vrachopoulos, M.Gr., Koukou, M.K., Filios A.E., Numerical investigation of the buoyancy-induced flow field and heat transfer inside solar chimneys, Int. Conference on Energy and Environmental Systems ‘06, Chalkida, Evia, 8-10 May, (2006). Available at:
    http://www.wseas.us/e-library/conferences/2006evia/papers/516-367.pdf
     
37. Hatziapostolou, A., K. Krallis, N. G. Orfanoudakis, M. K. Koukou, D. Chatzifotis, G. Raptis, Numerical Prediction of the Flow Field produced by a Laboratory-Scale Combustor: a Preliminary Isothermal Investigation Int. Conference on Energy and Environmental Systems ‘06, Chalkida, Evia, 8-10 May, (2006). Available at:
    http://www.wseas.us/e-library/conferences/2006evia/papers/516-370.pdf
     
38. Vrachopoulos, M.Gr., M.K. Koukou, N.W. Vlachakis, N.G. Orfanoudakis, G. Thanos, A.E. Filios, J. Kaldelis, ‘”Developing efficient tools to evaluate indoor environment issues: on-site measurements and numerical simulation of indoor air flow in a test room”, International Conference on Environment, Ecosystems, and Development, Venice, 2-4 November, (2005). Available at:
    http://www.wseas.us/e-library/conferences/2005venice/papers/508-365.pdf