Nick Grant

Nick GrantNick Grant is a freelance energy consultant and principal of Elemental Solutions. His interest in closing the performance gap between design and reality led him to the Passivhaus Standard of which he is one of the UK pioneers. He is an active contributor to discussions on sustainable design but is also a practical engineer and self builder. Nick was a long time Trustee of the AECB and is Technical Director of the Passivhaus Trust.


Alan Clarke

Alan Clarke

Alan is an energy consultant and building services engineer specialising in Passivhaus design. He has probably worked on more UK Passivhaus projects than anyone else. Nick and Alan worked together on some of the first UK Passivhaus Schools, many housing projects and the first Passivhaus Archives in the UK. We have co-authored many papers and technical articles, some of which are available to download here.  Alan has worked for Ove Arup, Max Fordham and Peter Warm but is now freelance.

Charles Decourcy Grylls

Charles GryllsCharles is an architect in practice with his wife Leah Dempsey. We first worked together when he was with Architype and work together on a steady stream of local Passivhaus projects including single family dwellings, extensions and deep retrofits with Mike Whitfield and Alan Clarke. Charles shares my passion for elegant simplicity and attention to detail. His construction drawings are the best I have seen.

Colin Chetwood

Colin ChetwoodColin and I first collaborated to design and manufacture lighting for Architype’s new Hereford office but are always keen to find excuses to work and play together. We developed an eco-minimal task lamp called Lock Lamp which Colin manufactures in his rural Herefordshire workshop.

Mike Whitfield

Mike WhitfieldMike helped us build our home in the late 90s and we regularly work together on a range of projects. Although Mike Whitfield Construction Ltd are masters of oak frames and natural stone they are Passivhaus converts and only work on very low energy buildings with a number of certified Passivhaus projects completed. Working with Charles Grylls we have developed very simple Passivhaus details for timber construction.

Andrew Warren

Andy WarrenAndy and I set up NatSol in 2005. The company designs and manufactures waterless toilets for remote sites. We had been sharing experience. I stepped down as Technical Director of Natsol at the start of 2021 due to other commitments but remain involved in a consultancy role.

Architype, Jono Hines

Jonathan Hines

Jono is an architect and the Managing Director of Architype. We have been working together on projects for many years, originally providing water and wastewater consultancy but with increasing amounts of input on construction details and energy efficiency. Many of the larger projects on this site are with Architype.

Bill Butcher

Bill Butcher

Bill is a director of the Green Building Company and is famous for, among other things, building the Denby Dale Passivhaus using traditional cavity wall construction. We teach together on the Carbonlite Passivhaus Designer Course and usually manage at least two building related road trip adventures each year.

Chris Herring

Chris Herring

Chris is Bill’s business partner. We are both directors of the Passivhaus Trust. We attended our first Passivhaus conference together in 2007 and have been going back ever since.

John Cantor

John Cantor

I met John at the Centre for Alternative Technology in about 1983. Since then we have collaborated on a wide range of projects including the evaluation of micro CHP, various heat pumps, a peak load controller for a cheese factory and most recently frozen film stores for the Imperial War Museum. He is the first person to call for any heat pump related questions..

Judith Thornton

Dr Judith ThorntonJudith is pulled into the team when research or papers with any pretension of scientific rigour are required. Her Phd is in Physiology but she is now working in the field of water, carbon and lifecycle analysis.  Major projects together include the AECB Water Standards, The EST Water and Carbon reports and the critique of the CSH water calculator with AECOM. Check out her excellent low carbon building blog here.

Kate de Selincourt

Kate de Selincourt

Kate is a freelance writer, editor and researcher specialising in sustainability and the built environment. She has had significant input in a number of the papers on this site as well as the BD Sustainability Blog. Kate is an excellent source of useful nuggets via Twitter (@Kate_de) and her blog.

Mark Siddall, LEAP

Mark Siddall

Mark is a Passivhaus architect. We have worked together on a number of technical papers and Passivhaus master classes including the internationally influential document ‘Claiming the Passivhaus Standard‘ which has been translated into Spanish. Mark is a very generous contributor on various forums with his encyclopaedic knowledge of building physics and practical experience.

Peter Warm

Peter WarmPete encouraged me to get involved in energy again after many years working with water. He set up Warm which is now run by his daughter Sally Godber. Warm runs the Passivhaus training which a number of us on this page are contributing authors and trainers.

Adrian Cook

Adrian Cook architect PowysAdrian is an architect based in Powys. We first worked together on his Father-in-law’s Passivhaus in Crickhowell built by Mike Whitfield. This lead to a number of new build and deep retrofit collaborations. Adrian comes from a conservation background and we share a love of simple details and materials done well.

Sheila Herring

Sheila HerringLast but not least, Sheila is a potter but she did most of the hard work designing and building our home. She worked on-site for over 4 years with Mike Whitfield Construction. Sheila helps keep the office organised and always offers a fresh viewpoint.