What We Do

Onoffice environmental architecture is a dynamic firm based in Athens, Greece that undertakes architectural projects from its initial concept through construction. Areas of expertise range from housing to urban design and private development planning and from interior design to open spaces and educational facilities.
Onoffice incorporates principles of sustainable architecture through the first steps of each project, practices environmentally responsible design and suggests solutions that save energy during construction and maintenance. Clientele includes government and municipal agencies, private corporations, real estate developers and private clients. Combining experience and expertise of its principles, collaborators and consultants, Onoffice provides high quality design, presentation and communication services.


Dimitris Antoniou

Architect NTUA, MA, MRE, Int’l Assoc. AIA

Architect NTU of Athens (1989). Master of Architecture in the Urban Landscape, University of Southern California, Los Angeles (1991). Master of Science in Real Estate Development and Valuation, Neapolis University Pafos (2017). Junior Designer (Athens, Los Angeles, 1983-1992). Set Designer, MCA/Universal Studios Hollywood (1992 – 93). Member of “Theros Architecture” (1994-1998). Chief designer of a variety of projects (houses, cinemas, theaters, industrial and commercial facilities). Collaborator, Kisho Kurokawa Assoc., (Embassy of Japan, Athens, 2003). Three first, two fourth prizes and four commendations in architectural competitions. Commendation in European Competition “Zephyr–Passive Cooling Techniques” (1994). PhD candidate scholarship. (1997). Assistant Professor of Architectural Design and Building Technology at Dept. of Architecture, University of Patras (2001-2004, 2009-2011), elected as tenure-track Assistant Professor (2010), and Democritus University (2005-2006). Visiting Lecturer, DCG (Drury Center in Greece), Dept. of Architecture, Drury University, Mo., U.S.A., 2006-2007. Assistant Professor of Architectural Design and Building Technology at Neapolis University Pafos, Cyprus (2011-2014). Assistant Professor of Architectural Design and Building Technology at Dept. of Architecture, University of Patras (2014-today). He has participated in thesis and project review committees at several universities and has been supervising architectural workshops in Greece and Cyprus. His projects, articles and book contributions, have been published. Co-founder, with Eleni Katsoufi, “ONOFFICE environmental architecture” in Athens (1998-today). Member of Do.Co.Mo.Mo., Technical Chamber of Greece, Technical Chamber of Cyprus, Architectural Associations in Greece and Cyprus, Member of ULI (Urban Land Institute) and Int’l Associate AIA (American Institute of Architects)

Eleni Katsoufi

Architect NTUA, MA USC

Graduated from the Architecture School of the National Technical University of Athens, in 1992. Received a Master of Architecture from the University of Southern California in 1994, where she held a scholarship and a teaching assistantship for two years. Worked as an intern at the offices of A. Zannos, D. Molfesis, and T. Papaioannou-D. Isaias-G. Makris and as a junior architect at Panos Koulermos Studio where she participated in urban design, architecture and research projects in Los Angeles. Founding member of “Kivos 4 Architecture and Urbanism” between 1995-1998. Chief designer in a variety of public and private projects dealing with urbanism and landscape. Collaboration with Kisho Kurokawa & Associates for the Embassy of Japan in Greece (2003). Work has been published in websites, magazines and books, participated in several group architectural exhibitions. One first prize, two second prizes as a student and tree commendations in European Architectural competitions. Adjunct professor for Hammons School of Architecture, Drury University, Springfield Mo and the Drury Center in Greece (2009-today). Co-founder, with Dimitris Antoniou, of “ONOFFICE environmental architecture” private practice in Athens (1998-today).

Marilena Tsevi

Architect University of Patras

Graduated from the School of Architecture of University of Patras in 2020. During her last year of studies, she worked as a junior architect at Lazaris Architects. She has participated in several architectural competitions. Since 2020, she has been involved in designing and implementing houses, hospitality and renovation projects as well as landscape and large scale projects. She is highly skilled in construction details design and 3D photorealistic design using 2D and 3D softwares. Marilena joined ONOFFICE environmental architecture in May of 2020.

Spyros Pyrgiotis

Architect University of Patras

Graduated from the School of Architecture of University of Patras in 2020. During his studies, he worked as an architectural Intern at Theodoros Timagenis Architects-Acoustics Consultans. He has participated in several architectural competitions. He is highly skilled in 3D photorealistic design using 3D softwares. Spyros joined ONOFFICE environmental architecture in November of 2021.

Stavroula Oikonomou

Architect University of Patras

She gratuated from the School of Architecture of University of Patras in August 2021. She worked for Gavalas Architects from July 2020 to January 2020. At the same time, she worked also as a freelance Architect in the field of houses renovation. In 2021 she joined Theros Architects as an Architect. She is highly skilled in construction details design. Stavroula joined ONOFFICE environmental architecture in November of 2022.

Μairy Manousaki

Interior Designer – Vakalo Art and Design Collage

Graduated from Department of Early Childhood Education of National and Kapodistrian University of Athens in 2016. She graduated from Vakalo Art and Design Collage as an Interior designer in 2019. From 2020 to 2022 she worked at Trail architects and designers practice. Currently, she is continuing her studies at the National and Technical University of Athens. She is highly skilled in 3D modeling and Technical drawings. Mary joined ONOFFICE environmental architecture in July of 2023.


2nd Prize.“NAMS – New Archaeological Museum of Sparta”, Peloponissos Prefecture, Greece.
Collaboration: M. Gerogiannaki, E. Demopoulou, P. Theodoropoulou, P. Kyriakopoulou,
T. Pantazopoulou, A. Papamanolis, D. Petratou, A. Tsitsimbi.
Distinction.Short-listed in the 50 Finalists amongst 500 participants
in the International Competition for a School and Housing complex in Benga, Malawi.
Teamed with Pelagia Spyridonidou and Katerina Ritsoni, students of Architecture.
2nd Prize. “Green Urban Parks”. As an advisor to the Student Competition
organized by WWF and AUTh .Student: M. Diamantopoulou.
1st Prize. Germanina Estate and Botanical Park, Geroskipou, Cyprus.
European Competition. Collaboration: M. Dimitroglou, P. Leventis, M. Aggelaki.
Honorable Mention.  Pallourokampos Park, Latsia, Cyprus.
European Competition.Collaboration: M. Dimitroglou, M. Damianou, P. Leventis.
Honorable Mention.  Ministry of Environment and Climate Change.
Ideas for the uses of plantation on roofs and facades and pilot applications.
Honorable Mention. Urban park on block 106, Filothei, Athens.
National competition.
Honorable Mention. Zefyri Cultural Center, Athens.
National Competition. Collaboration: Theros Architecture.
4th Prize.  Administration Center and Restaurant for Fine Arts School, Athens. National Competition.
Collaboration: Theros Architecture.
Commendation. “Zephyr” European Competition on “Passive Cooling Techniques for Buildings”.
UCL & University of Dublin, Dublin, Ireland. Collaboration: S. Tsiraki, G. Christofilis
1st Prize. Elinoil Petroleum S.A. Prototype Gas Station for the Greek Islands.
National Competition. Collaboration: B. Yannoutsou, T. Biris.
2nd Prize. New Archeological Museum of Patras. National Competition.
Design team: D. Isaias, T. Papaioannou, G. Makris.
2nd Prize. Kalyvia Cultural Center, Attica. National Competition.
Design team: N. Goulias, Ergon ltd.
4th Prize. New Municipality Building, Loutraki, Peloponesse.
Collaboration: C. Govetta
1st Prize. Ministry of Environment and Public Works. Ideas for Prototype houses.
Collaboration: B. Yannoutsou, K. Grigoratos, K. Vrettou, Prof. D. Biris.
Space and the Architecture of Compassion. Kakogiannis Foundation.
Kenya Project. As Professor of Architecture with students from the University of Patras.
Health in the City. As Professor of Architecture with students from Drury University.
8th National Architecture Exhibition. (8th SANA Biennale ) Architect’s Association in Patras.
Germanina Estate and Park, Thematic Archeological Museum.
DOMES INDEX international discourse platform. Neohellenic Architectural Archive. Two (2) Onoffice projects
Imagine the City, Aegina. Urban Park at the Edge of Town.
Instructor of Architecture students from Drury University.
6th Biennale of Greek Architects. Hellenic Institute of Architecture, Athens.
School Complex in the city of Xanthi, Greece
META 5th Architecture Exhibition by the Architect’s Association in Thessaloniki.
Passive Solar House in the Historic Center of Xanthi, Greece.
3rd Triennale of Architecture, Center for Mediterranean Architecture, Chania, Crete. Street and Pedestrian network in the traditional village of Archanes, Crete.
Village was awarded with second prize in EU for its well preserved historic fabric.
RELAND-Real Estate and Land Planning International Conference, Mykonos, Greece, September 2018. Speakers: D. Antoniou, T. Dimopoulos, Presented Article: “Southern Orientation and Natural Cross Ventilation: Mind the Gap(s)- What Clients, Valuers, Realtors and Architects Believe” Real Estate and Land Planning International Journal 2018. pages: 426-439. Published by Aristotle University of Thessaloniki, Greece.
Lecture. “Afritecture -The works of F. Kere and TAM Associati” in the context of the CAA Workshop “Design-Aid in Nairobi”, Nicosia, Cyprus.
Summer Workshop. Cyprus Architects Association “Design Aid in Nairobi, Kenya”.
Responsible co-organizer on behalf of Dept. of Architecture, University of Patras
3rd Sustainable Development Solutions Network Mediterranean Conference.
Participation. UN SDSN Greece.
Summer Workshop. Cyprus Architects Association (2016) “Discover / Uncover / Recover”.
Responsible on behalf of Neapolis University Pafos, Pafos. Collaboration: S. Xenopoulos and Y. Koutsolambros.
ECCOMAS Congress VII European Congress on Computational Methods in Applied Sciences and Engineering. Crete. Paper Presentation: “Form Finding on Parametric Surfaces. Optimization and Correlations of Architectural Fluidity and Structural Response”.
Other authors: K. Liapi, N. Bakas.
Lecture “Le Corbusier – The painter”
Speaker in the context of the celebration for the 50 years from the death of Le Corbusier.
Neapolis University Pafos.
Lecture “Thoughts on Ecology” in the context of “Week of Architecture”
organized by the Cyprus Architects Association.
Workshop. “Urban Mobile Cultural Units” Invited as a Speaker and jury member.
Lecture Title: “Thinking Ephemeral Architecture Today”, Pafos.
Lecture “The meaning of Bauhaus”
Speaker in the context of the celebration of 80 years after the Bauhaus School closed.
Neapolis University Pafos.
Summer Workshop. Cyprus Architects Association “Urban Equilibrium”.
Responsible on behalf of Neapolis University Pafos.
Collaborated with G. Artopoulos and M. Sioulas.
Workshop Physics Society of Cyprus. “Energy-Conscious Design”. Invited Speaker.
Lecture title: “Thoughts on Green Development”, Neapolis University Pafos.
Architectural page in Social Media – Administrator for Facebook Page “FreeArchBook” on architectural sketches, planned to be a published book. Visited by over 35.000 users globally.
Workshop Coordinator. 13th Venice Biennale. Cyprus Pavillion. “Revisit Cyprus”. Article in Biennale Cypriot catalogue. Title: “Once more… Architecture as a catalyst”.
Lecture. Invited Speaker. Lecture title: “On Greek Modernism” Ryerson University Toronto.
School of Architecture. Graduate Program
Book Contributor. Book Title: “Travel as Architectural Education”. Ryerson University, Toronto, Canada. Long-distance Lecturer and Reviewer. Article. Title: On our visit to Pikionis’s “Loumbardiaris Project”.
11th Conference of Greek Architects, Athens. Speaker. Thematic Circle: Politics for Architecture in Greece. Paper Title: “Restrictions (?) in Urban Design in Greek Cities today”.
3rd International Symposium of RE+D Publication: Investment Opportunities in Greece. Speaker and moderator of panel: Urban Regeneration – Setting up the green debate.
3rd Scientific meeting of Do.Co.Mo.Mo. (Documentation and Conservation of buildings, sites and neighborhoods of the Modern Movement). Speaker. Paper Title: “A hypothesis for the teaching of the Modern today”.
Bioclimatic Architecture in office buildings. Participation.
European Renewable Energy Centers Agency, UIA, Greek Technical Chamber.
Myrto Tzanaki
Eleni Varela
Xristina Kalogianni
Zoi Papadimitriou
Nikoletta Dimitriou
Maria Gerogiannaki
Evgenia Demopoulou
Peggy Theodoropoulou
Panagiota Kyriakopoulou
Tzortzina Pantazopoulou
Antonis Papamanolis
Daphne Petratou
Kanelia Koutsandrea
Dimitris Theodorou
Naya Theofilakou
Maria Paneta
Maria Hasioti
Marianna Mourla
Giouli Stylianidou
Matina Aggelopoulou
Maria Aretaki
Maria Bourika
Panagiotis Kostoulas
Ion Sklavounos
Ioanna Georgitsopoulou
Stefania Politi
George Dimitrakopoulos
Marianna Karanasou
Christina Voutou
Nasos Athanasopoulos
Maria Damianou
Manos Gogoulis
Argiro Kourmoulaki
May Aggelaki
Maria Koltsaki
Alexandros Kallegias
Daisy Ditsa
Aggela Dagla
Pola Chrona
Dimitris Tsioris
Ada Dipla
Aggeliki Bakogianni
Stella Antoniou
Anna Stratoudaki
Maria Kapaniri