1. Maria K. Koukou, John Konstantaras, George Dogkas, Kostas Lymperis, Vassilis N. Stathopoulos, Michail Gr. Vrachopoulos, Eleni Douvi, Υannis Caouris, Petros Dimas, Investigation of an innovative flat-plate integrated collector-storage solar water heater with latent heat storage, International Journal of Thermofluids, Volume 26, 2025, ISSN 2666-2027, 
   Available online at: https://doi.org/10.1016/j.ijft.2025.101091
    
2. Koukou, M.K.; Lucas, S.; Justino, J.; Rafael, S.; Livieratos, A.D.; Carriço, N.; Konstantaras, J.; Vrachopoulos, M.G.; Benedetti, A.C.; Mazzoli, C.; et al. Training for Sustainable and Healthy Building for 2050: New Methodologies for an Integrated and Transnational Education Approach Targeting Skills Development for the Transition Toward ZEB and PEB Buildings. Buildings 2025, 15, 67.
   Available online at: doi.org/10.3390/buildings15010067
    
3. Dimitra I. Pomoni, Maria K. Koukou, Michail Gr. Vrachopoulos, Labros Vasiliadis, Circular economy: A multilevel approach for natural resources and wastes under an agri-food perspective, Water-Energy Nexus, Volume 7, 2024, Pages 103-123, ISSN 2588-9125,
   Available online at: doi.org/10.1016/j.wen.2023.12.003.
    
4. Dimitrios Tsimpoukis, Evangelos Syngounas, Evangelos Bellos, Maria Koukou, Christos Tzivanidis, Stavros Anagnostatos, Michail Gr. Vrachopoulos, Data-driven energy efficiency comparison between operating R744 and R448A supermarket refrigeration systems based on hybrid experimental-simulation analysis, Thermal Science and Engineering Progress, Volume 53, 2024, ISSN 2451-9049,
   Available online at: doi.org/10.1016/j.tsep.2024.102776.
    
5. Coelho, L.; Koukou, M.K.; Konstantaras, J.; Vrachopoulos, M.G.; Rebola, A.; Benou, A.; Karytsas, C.; Tourou, P.; Sourkounis, C.; Gaich, H.; et al. Assessing the Effectiveness of an Innovative Thermal Energy Storage System Installed in a Building in a Moderate Continental Climatic Zone. Energies 2024, 17, 763.
   Available online at: https://doi.org/10.3390/en17030763 
    
6. Angeliki Kitsopoulou, Dimitris Pallantzas, Christos Sammoutos, Panagiotis Lykas, Evangelos Bellos, Michail Gr. Vrachopoulos, Christos Tzivanidis, A comparative investigation of building rooftop retrofit actions using an energy and computer fluid dynamics approach, Energy and Buildings, Volume 315,2024, ISSN 0378-7788,
   Available online at: doi.org/10.1016/j.enbuild.2024.114326.
    
7. Angeliki Kitsopoulou, Evangelos Bellos, Christos Sammoutos, Panagiotis Lykas, Michail Gr Vrachopoulos, Christos Tzivanidis, A detailed investigation of thermochromic dye-based roof coatings for Greek climatic conditions, Journal of Building Engineering, Volume 84, 2024, ISSN 2352-7102,
   Available online at: doi.org/10.1016/j.jobe.2024.108570
    
8. Dimitra I. Pomoni, Maria K. Koukou, Michail Gr. Vrachopoulos, Labros Vasiliadis, Circular economy: A multilevel approach for natural resources and wastes under an agri-food perspective, Water-Energy Nexus, 2024,
   Available online at: https://doi.org/10.1016/j.wen.2023.12.003
    
9. N.T. Panagiotopoulos, A.G. Lekatou, K.A. Agrafioti, C.C. Prouskas, M.K. Koukou, J. Konstantaras, K. Lymperis, M.Gr. Vrachopoulos, G.A. Evangelakis, Anticorrosive AlN coatings for heat exchangers in thermal energy storage systems, Thermal Science and Engineering Progress, Volume 43, 2023, 102014
   Available online at: https://doi.org/10.1016/j.tsep.2023.102014
    
10. A. Kitsopoulou, E. Bellos, P. Lykas, M.Gr. Vrachopoulos, C. Tzivanidis, Multi-objective evaluation of different retrofitting scenarios for a typical Greek building, Sustainable Energy Technologies and Assessments 57, 2023, 103156
    Available online at: https://doi.org/10.1016/j.seta.2023.103156
     
11. Bellos, E.; Lykas, P.; Tsimpoukis, D.; Korres, D.N.; Kitsopoulou, A.; Vrachopoulos, M.G.; Tzivanidis, C. Multicriteria Analysis of a Solar-Assisted Space Heating Unit with a High-Temperature Heat Pump for the Greek Climate Conditions. Appl. Sci. 2023, 13, 4066.
    Available online at: https://doi.org/10.3390/app13064066
     
12. Dimitrios Tsimpoukis, Evangelos Syngounas, Evangelos Bellos, Maria Koukou, Christos Tzivanidis, Stavros Anagnostatos, Michail Gr Vrachopoulos, Optimization analysis of Organic Rankine Cycle powered by waste heat of a supermarket transcritical CO2 multi-ejector refrigeration cycle, Journal of Cleaner Production, Volume 418, 2023, 138106,
    Available online at: https://doi.org/10.1016/j.jclepro.2023.138106
     
13. Pomoni, Dimitra I., Maria K. Koukou, Michail Gr. Vrachopoulos, and Labros Vasiliadis. 2023. "A Review of Hydroponics and Conventional Agriculture Based on Energy and Water Consumption, Environmental Impact, and Land Use" Energies 16, no. 4: 1690.
    Available online at: https://doi.org/10.3390/en16041690
     
14. Bellos, E.; Tsimpoukis, D.; Lykas, P.; Kitsopoulou, A.; Korres, D.N.; Vrachopoulos, M.G.; Tzivanidis, C. Investigation of a High-Temperature Heat Pump for Heating Purposes. Appl. Sci. 2023, 13, 2072.
    Available online at: https://doi.org/10.3390/app13042072
     
15. Kitsopoulou, A.; Bellos, E.; Lykas, P.; Sammoutos, C.; Vrachopoulos, M.G.; Tzivanidis, C. A Systematic Analysis of Phase Change Material and Optically Advanced Roof Coatings Integration for Athenian Climatic Conditions. Energies 2023, 16, 7521.
    Available online at: https://doi.org/10.3390/en16227521
     
16. Dimitrios Tsimpoukis, Evangelos Syngounas, Evangelos Bellos, Maria Koukou, Christos Tzivanidis, Stavros Anagnostatos, Michail Gr. Vrachopoulos, Thermodynamic and economic analysis of a supermarket transcritical CO2 refrigeration system coupled with solar-fed supercritical CO2 Brayton and organic Rankine cycles, Energy Conversion and Management: X, Volume 18, 2023, 100351
    Available online at: https://doi.org/10.1016/j.ecmx.2023.100351
     
17. Konstantaras J., Pagkalos C., Koukou M.K., Lymperis K., Caouris Y., Vrachopoulos M.G. Controller Evaluation for Solar-Latent Thermal Energy Applications. Journal of Energy and Power Technology 2022;4(2):18; DOI: 10.21926/jept.2202021
     
18. Maria K. Koukou, Christos Pagkalos, George Dogkas, Michail Gr. Vrachopoulos, Eleni Douvi, Yannis G. Caouris, Polykarpos Papadopoulos, Computational approach of charging and discharging phases in a novel compact solar collector with integrated thermal energy storage tank: study of different Phase Change Materials, Energies 2022, 15(3), 1113;
    Available online at: https://doi.org/10.3390/en15031113
     
19. Evangelos Syngounas, Dimitrios Tsimpoukis, Maria K. Koukou, Michail Gr. Vrachopoulos, Energetic, exergetic and financial evaluation of a solar-powered absorption chiller integration into a CO2 commercial refrigeration system, Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy (2022), Volume 236, Issue 6.
    Available online at: https://doi.org/10.1177/09576509221077540
     
20. Evangelos Syngounas, Dimitrios Tsimpoukis, Maria K. Koukou, Michail Gr. Vrachopoulos, Integration of a solar-powered absorption chiller for the performance enhancement of a supermarket CO2 refrigeration plant, Green Energy Sustain. 2(1):0003, (2022)
    Available online at: https://doi.org/10.47248/ges2202010003
     
21. Coelho, L.; Koukou, M.K.; Dogkas, G.; Konstantaras, J.; Vrachopoulos, M.G.; Rebola, A.; Benou, A.; Choropanitis, J.; Karytsas, C.; Sourkounis, C.; Chrysanthou, Z. Latent Thermal Energy Storage Application in a Residential Building at a Mediterranean Climate. Energies 2022, 15, 1008.
    Available online at: https://doi.org/10.3390/en15031008
     
22. Dimitrios Tsimpoukis, Evangelos Syngounas, Evangelos Bellos, Maria Koukou, Christos Tzivanidis, Stavros Anagnostatos, Michail Gr. Vrachopoulos, Investigation of energy and financial performance of a novel CO2 supercritical solar-biomass trigeneration system for operation in the climate of Athens, Energy Conversion and Management, Vol. 245, 114583, (2021)
    Available online at: https://doi.org/10.1016/j.enconman.2021.114583
     
23. Eleni Douvi, Christos Pagkalos, George Dogkas, Maria K. Koukou, Vassilis N. Stathopoulos, Υiannis Caouris, Michail Gr. Vrachopoulos, Phase Change Materials in Solar Domestic Hot Water Systems: A review, International Journal of Thermofluids, Vol. 10, 100075, (2021)
    Available online at: https://doi.org/10.1016/j.ijft.2021.100075
     
24. G. Dogkas, J. Konstantaras, M.K. Koukou, M.Gr. Vrachopoulos, C. Pagkalos, V.N. Stathopoulos, P.K. Pandis, K. Lymperis, L. Coelho, A. Rebola, Development and experimental testing of a compact thermal energy storage tank using paraffin targeting domestic hot water production needs, Thermal Science and Engineering Progress, Vol. 19, 100573 (2020)
    Available online at: https://doi.org/10.1016/j.tsep.2020.100573
     
25. G. Dogkas, M.K. Koukou J. Konstantaras, C. Pagkalos, K. Lymperis, V.N. Stathopoulos, L. Coelho, A. Rebola, M.Gr. Vrachopoulos, Investigating the performance of a thermal energy storage unit with paraffin as phase change material, targeting buildings’ cooling needs: an experimental approach, International Journal of Thermofluids, Vol 3-4, 100027 (2020)
    Available online at: https://doi.org/10.1016/j.ijft.2020.100027
     
26. M.K. Koukou, G. Dogkas, M.Gr. Vrachopoulos, J. Konstantaras, C. Pagkalos, V.N. Stathopoulos, P.K. Pandis, K. Lymperis, L. Coelho, and A. Rebola, Experimental assessment of a full-scale prototype thermal energy storage tank using paraffin for space heating application, International Journal of Thermofluids, Vol 1-2, 100003 (2020)
    Available online at: https://doi.org/10.1016/j.ijft.2019.100003
     
27. C. Pagkalos, G. Dogkas, M.K. Koukou, J. Konstantaras, K. Lymperis. M.Gr. Vrachopoulos, Evaluation of Water and Paraffin PCM as Storage Media for use in Thermal Energy Storage Applications: A Numerical Approach, International Journal of Thermofluids, Vol 1-2, 100006 (2020)
    Available online at: https://doi.org/10.1016/j.ijft.2019.100006
     
28. Evangelos Bellos, Michalis Gr. Vrachopoulos, Christos Tzivanidis, Theoretical investigation of a novel hybrid refrigeration cycle based on the partial thermal isochoric compression, Thermal Science and Engineering Progress, Volume 11, June 2019, Pages 239-248.
    Available online at: https://doi.org/10.1016/j.tsep.2019.04.003
     
29. M.K. Koukou; Dogkas, G.; Vrachopoulos, M.G.; Konstantaras, J.; Pagkalos, C.; Lymperis, K.; Stathopoulos, V.; Evangelakis, G.; Prouskas, C.; Coelho, L.; Rebola, A. Performance Evaluation of a Small-Scale Latent Heat Thermal Energy Storage Unit for Heating Applications Based on a Nanocomposite Organic PCM. ChemEngineering 3, 88, (2019).
    Available online at: https://doi.org/10.3390/chemengineering3040088
     
30. P.K. Pandis, S. Papaioannou, M.K. Koukou, M.Gr. 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, Energy Procedia, 161, 429-437, (2019).
    Available online at: https://www.sciencedirect.com/science/article/pii/S1876610219311683
     
31. Vasiliki Chalkia, Nikolaos Tachos, Pavlos K. Pandis, Aris Giannakas, Maria Koukou, Michalis Vrachopoulos, Luis Coelho, Athanasios Ladavos, Vassilis N. Stathopoulos, «Influence of organic phase change materials on the physical and mechanical properties of HDPE and PP polymers», RSC Adv., 8, 27438–27447 (2018).
    Available online at: https://pubs.rsc.org/en/content/articlepdf/2018/ra/c8ra03839b
     
32. M.K. Koukou, M.Gr. Vrachopoulos, N. S. Tachos, George Dogkas, Kostas Lymperis, and Vassilis Stathopoulos, "Experimental and computational investigation of a latent heat energy storage system with a staggered heat exchanger for various phase change materials", Thermal Science and Engineering Progress 7, 87–98, (2018) Open Access.
    Available online at: https://www.sciencedirect.com/science/article/pii/S2451904917303128
     
33. M.K. Koukou, M.Gr. Vrachopoulos, N. Tachos and N. Tsolakoglou, Design and development of a 10kWe ORC installation working with low temperature sources, 37 (9), 857-872 (2018).
    Available online at: https://www.tandfonline.com/doi/full/10.1080/14786451.2017.1383991
     
34. M.Gr. Vrachopoulos, N. Tachos, M.K. Koukou, G.K. Karanasiou, C. Karytsas, P. Tsekouras, and V. Drosou, Pre-assessment of a low-temperature geothermal and solar ORC system for power co-generation: the Effi low res approach, WSEAS TRANS ON ENVIRONMENT AND DEVELOPMENT, Vol. 11, 228-236, (2015).
    Available online at: http://www.wseas.org/multimedia/journals/environment/2015/a505815-093.pdf
     
35. M. Gr. Vrachopoulos, E. Kravvaritis, D. G. Stavlas, V. Stamatopoulos, A. Gonidis, and M. K. Koukou, Investigating the performance of a test phase change material chamber for passive solar applications: experimental and theoretical approach, International Journal of Sustainable Energy, Volume 34, 9, pp 614-627, (2015).
    Available on line at:https://www.tandfonline.com/doi/full/10.1080/14786451.2013.853065
     
36. 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”, Journal of Environmental Science, Vol. 3, pp 182-187 (2014). Available online at: http://environment.scientific-journal.com/toc/volume-3.html
     
37. M.Gr. Vrachopoulos, M.K. Koukou, G. Filos and C. Moraitis, Investigation of heat transfer in a triple-glazing type window at Greek climate conditions, Centr. Eur. J. Eng., 3(4) pp 750-763 (2013).
    https://doi.org/10.2478/s13531-013-0130-9 
     
38. Thanos G., Vrachopoulos M.Gr., Koukou M.K., Koulis A., Kakouris A.P., Thanos A.G., Residence site selection in urban and rural areas in Greece: A multiple-criteria decision analysis approach, Int. J. Applied Management Science, Vol. 4, n. 1, 36-51, (2012). https://doi.org/10.1504/IJAMS.2012.044870
     
39. Vrachopoulos, M.Gr. M.K. Koukou, D.G. Stavlas, V.N. Stamatopoulos, A.F. Gonidis, E.D. Kravvaritis, Testing reflective insulation for improvement of buildings energy efficiency, Central European Journal of Engineering, Vol. 2 n. 1, 83-90 (2012). https://doi.org/10.2478/s13531-011-0036-3
     
40. Vrachopoulos, M.Gr., M.K. Koukou, D.G. Stavlas, V.N. Stamatopoulos, A.F. Gonidis, E.D. Kravvaritis, Enhancement of Solar Thermal Energy Storage using Phase Change Materials: an Experimental Study at Greek Climate Conditions, International Review of Mechanical Engineering (IREME), Vol. 5 n. 2, pp. 279-284 (2011)
     
41. Stavrakakis, G.M., Koukou, M.K., Vrachopoulos, M.Gr., Markatos, N.C., Natural Cross-Ventilation in Buildings: Building-scale Experiments, Numerical Simulation and Thermal Comfort Evaluation, Energy & Buildings 40, 9, 1666-1681, (2008). https://doi.org/10.1016/j.enbuild.2008.02.022
     
42. Bacharoudis, E., Vrachopoulos, M.Gr., Koukou, M.K., Margaris, D., Filios, A.E., Mavrommatis, S.A., Study of the natural convection phenomena inside a wall solar chimney with one wall adiabatic and one wall under a heat flux approach, Applied Thermal Engineering, 27, 2266–2275, (2007).
    https://doi.org/10.1016/j.applthermaleng.2007.01.021
     
43. Papaefthimiou, V.D., Katsanos, C.O., Vrachopoulos, M.Gr., Filios, A.E., Koukou, M.K., Layrenti F.G., Experimental measurements and theoretical predictions of flow field and temperature distribution inside a wall solar chimney, Proc. IMechE Vol. 221 Part C: J. Mechanical Engineering Science, 33-41, (2007).
    https://doi.org/10.1243/0954406JMES308
     
44. Zervas, P., M.K. Koukou, N.C. Markatos, Predicting the effects of process parameters on the performance of phosphoric acid fuel cells using a 3-D numerical approach, Energy Conversion and Management, Vol. 47, no. 18-19, 2883-2899, (2006). https://doi.org/10.1016/j.enconman.2006.03.030
     
45. Zervas, P., M.K. Koukou, N.G. Orfanoudakis, N.C. Markatos, Evaluating low-temperature fuel cells performance for power generation: fluid dynamics study of PAFC systems at the cell level, Proc. IMechE Vol. 220 Part A: J. Power and Energy, 220 (6), pp. 525-533(9) (2006).
    https://doi.org/10.1243/09576509JPE229
     
46. 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, WSEAS Transactions on Fluid Mechanics, Issue 3, Vol. 1, 230-236, (2006).
    http://wseas.us/e-library/conferences/2006evia/papers/516-370.pdf
     
47. 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, WSEAS Transactions on Heat and Mass Transfer, Issue 2, Vol. 1, 193-198, (2006). http://www.wseas.us/e-library/conferences/2006evia/papers/516-367.pdf
     
48. 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, WSEAS Transactions on Environment and Development, Issue 3, Vol. 2, 173-178, (2006).
    http://www.wseas.us/e-library/conferences/2006evia/papers/516-366.pdf
     
49. 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”, WSEAS Transactions on Environment and Development, Issue 2, Vol. 1, 288-293, (2005)