Marion Baeli is Principal, Sustainability Transformation at 10 Design. Specialising in the existing built environment, adaptive reuse and low energy , low carbon design, she brings in over 20 years of expertise on the design and delivery of large-scale, complex projects that span the whole spectrum of housing as well as office sectors.

She is a renowned author on low-energy design, recognised for her award-winning book on residential retrofits.Additionally, she is a government advisor on retrofit for the Department of Energy Security and Net Zero, contributes to the Westminster City Council's Design Review Panel, serves as a frequent guest lecturer at several Universities (UCL, Westminster, Imperial College) sits on the board of the UK Passivhaus Trust and acts as an architecture award judge for the RIBA, the Architects’ Journal, CTBUH and Architecture Today.

Marion Baeli is Principal, Sustainability Transformation at 10 Design and a recognised trailblazer in the transformation of the existing built environment. For over 20 years, she has been at the forefront of adaptive reuse and low-energy, low-carbon design—reshaping how complex, large-scale buildings across the housing and office sectors are reimagined for a net-zero future.

A leading authority on retrofit, Marion has been instrumental in moving low-energy design from the margins into mainstream practice. Her award-winning book on residential retrofits is widely regarded as a seminal reference, influencing both professional delivery and national policy. As a government advisor on retrofit to the Department for Energy Security and Net Zero, she plays a pivotal role in shaping the UK’s approach to decarbonising existing buildings.

Driving change at scale, Marion has created a unique, globally deployed EcoDesign module that embeds sustainability at the earliest stages of design, influencing the work of over 1,600 architects worldwide and fundamentally shifting design culture within a global practice.

Her influence spans policy, industry and education. Marion is Co-Chair of the influential Urban Land Institute European Sustainability Product Council, sits on the board of the UK Passivhaus Trust, advises Westminster City Council’s Design Review Panel, lectures at leading universities, and serves as an awards judge for RIBA, Architects’ Journal, CIBSE and CTBUH.