Qualified in Part 1, 2 and 3 of the RIBA Architecture Programme at Cambridge University, Mark Hewitt trained with leading environmental architects Short Ford and Partners.
His professional and academic work has been focused on developing solutions for sustainable and energy-efficient building.

He is a founding partner with Clare Gerrard of d-squared.

As a Senior Lecturer in Architecture at the University of North London (1990-2000), Mark Hewitt developed a post-graduate course focusing on building physics and architectural design. He has also engaged in a series of research projects looking at large scale energy effects in building fabric. The results of this work have been widely published, and include the book "City Fights: debates on Urban Sustainability" (James and James Science Publishers, London 2001).

In 1998 Mark Hewitt began a research and development project for the use of interseasonal heat storage technology in large scale building and infrastructure applications. This work was recently recognised with the award of a major Carbon Trust award (2004) to demonstrate the technology for schools.