Tim Martel – Passivhaus Designer & Retrofit Coordinator


Passivhaus Designer
Chartered Architectural Technologist
Retrofit Coordinator & AECB REALcosting author
Withdene, Frome Park Road, Stroud, Glos GL5 3LF

01453 759466 

M: 07531 288147

E: tim@optimalretrofit.co.uk
Web: www.optimalretrofit.co.uk


Tim assists architects and home owners with low energy designs of houses, particularly retrofits, also known as eco-renovation. He recently qualified as a Retrofit Coordinator and is a Chartered Architectural Technologist, Passivhaus Designer and one of the tutors for the AECB (Assn of Environment Conscious Builders) Carbonlite Retrofit course. He’s given about a dozen talks on the economics of retrofit at conferences and has also had articles published in magazines.


Insulation and Moisture Risk Expertise
Tim can visit your home, troubleshoot issues and give advice on options and solutions.

Building Regulations
Design compliance consultancy.

Chartered Architectural Technologist
Tim uses the the revolutionary Revit BIM software which allow designs to be viewed in 3D from any angle as well as the full drawing set.

Passivhaus Design
Passivhaus is a German standard of building design that saves 90% of heating energy, compared to normal houses. Energy calculations are central to low energy building design and accurate calculations are needed to estimate the level of comfort and energy savings. Tim has been a Passivhaus Designer since 2012 and is an expert in the Passivhaus Planning Package (PHPP) which is more rigorous than other energy software and links to REALcosting. 

Retrofit Coordination
The role of retrofit coordinator is relatively new and combines a wide range of technical expertise that very few building professionals have. Upgrading the energy performance of existing buildings requires expert advice and Tim is an Architectural Technologist with specific training and experience in retrofit. Services are listed here are offered before, during and after the retrofit:


  • Moisture Survey to check the suitability of a building
  • Energy calculations
  • Indication of typical costs and affordability, using the AECB’s REALcosting software (Tim designed and sells this product)
  • Implement a well-integrated retrofit package


  • Manage the process from start to end
  • Assure quality of design
  • Quality checking of the installation
  • Manage risks and protect the clients interests


  • If necessary, monitoring surveys to assess long term moisture and mould risk

Tim Martel - Passivhaus Designer & Retrofit Coordinator