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Our team

Many hands, working together as one.



6    Partners

10  Registered architects

6    Revit operators

3    Interns

5    Administratives

30 Coworkers in total


9    LEED Accredited Professionals / Green Associates

2    EDGE Experts

Vice-president, founding partner

Carlos Ossenbach


Our founding partner and current vice-president of OPB Arquitectos is an architect with great prestige in the area of profession. After studying in Aachen, Germany and graduating with a degree in Engineering and a Masters in Architecture, he founded the company in 1977, with the idea of leading an architectural firm that would be part of the constant development in technology and design, without neglecting sustainability.

Today, thanks to his vision and work, OPB has collaborated with transnational firms such as Siemens, Metalco, Intel and Boston Scientific.


Sebastian Klus


Sebastian Klus today is a key player in our firm. He became partner in 2013 and was promoted to vice-president and chief of operations in 2024.

Born in Essen, Germany, he earned his Bachelor of Engineering and Master of Architecture with emphasis in project management at the Technical University of Dortmund. He joined OPB Architects in 2004 and in 2009 was promoted to Director of Production. He was accredited LEED AP BD + C from the US Green Building Council in 2009. Sebastian recently obtained his MBA, with a specialization in management, from the University of Costa Rica.

New business development

Ramón Pendones


Ramón Pendones was our first associate thanks to his trajectory and work within our firm. After graduating as a Bachelor of Architecture from UACA, obtaining a degree in Architecture and an MBA with emphasis in Banking and Finance from UCR, he began his career with us in 1986. Twelve years after working together, he joined OPB as a partner.

His contributions to our firm and to Costa Rican architecture are remarkable. For example, the leadership of projects such as Intel, Terramall, Boston Scientific and the El Tobogán Corporate Center.

Currently, Ramón is in charge of the development of new businesses at the firm. He is also a strong believer in activism and founded Aconvivir, an organization that seeks to develop less harmful and quieter urban transportation. He is also currently pursuing his Master's degree in Urbanism.

Production manager

Javier Chaves


Javier has been with us since 2006 and became Design Manager in 2009. Four years later he became an associate of OPB.

He studied Architecture at the University of Costa Rica and since 2009 he is a LEED AP BD+C accredited professional by the Green Building Certification Institute.

Construction manager

Álvaro Castro


Since 1998 Álvaro began to venture into the world of architecture when he started his university studies at Véritas University. In 2004 he obtained his bachelor's degree from the university. To conclude his studies, he completed a Master's Degree in Urban Design from which he graduated and another in Project Management from the University of International Cooperation (UCI).

In 2016 he obtained the certification as Auditor Edge, a new standard for sustainable design.

Design manager

Marco Castro


Marco's day-to-day responsibilities include large projects. He earned his degree from the University of Costa Rica, and started working at OPB Arquitectos in 2006. He was quickly promoted to Assistant Design Manager and in 2014 to Production Manager, becoming a partner at OPB in 2015. During his nine years with our firm, he has been involved in projects such as the Walmart Escazú, Pacífico Resort, Iribó and Yorkín schools and the new buildings and laboratories of the Engineering department of the University of Costa Rica. In 2010 he received his certification as a LEED AP B + C professional from the US Green Building Council; in 2015 he was certified in EDGE design.