Bill is a co-founder and director of 21° formerly Green Building Store (GBS), a Passivhaus consultant, and has led the construction arm of the business for many years. He has led on numerous Passivhaus projects, including the Denby Dale Passivhaus, alongside developing a Passivhaus approach to several radical retrofits. Having originally trained as a quantity surveyor, Bill has over 45 years of practical building experience. His pioneering work on the Longwood low-energy house in the early 1990s was the beginning of his low-energy and Passivhaus journey.

He co-founded Green Building Store in 1995/ 21° which has evolved into a leading national design and supplier of Passivhaus windows and doors, MVHR ventilation systems, and airtightness products.

Bill is a passionate advocate for better building in the UK, seeing the Passivhaus standard as exemplary for the UK industry in meeting its climate change responsibilities. He is committed to making the lessons he has learned from Passivhaus accessible and easily understandable for the wider construction industry.