top of page


LETI is a voluntary network of over 1,000 built environment professionals, working together to put the UK and the planet on the path to a zero carbon future. Our vision is to understand and clarify what this means in the built environment and develop the actions needed to meet the UK climate change targets. 

Our volunteers are made up of developers, engineers, housing associations, architects, planners, academics, sustainability professionals, contractors and facilities managers, with support and input provided by local authorities and other organisations.


Originally the ‘London Energy Transformation Initiative’ (LETI) was established in 2017 to support the transition of the London’s built environment to meet Net Zero Carbon. Since then, LETI has formed as a Community Interest Company and altered our name to become the ‘Low Energy Transformation Initiative’, but predominantly we are known as LETI. This reflects our interest in all UK zero carbon policy and regulation.


What LETI has achieved so far

In 2017 and 2018 LETI's focus was to influence energy policy in London including the draft London Plan and the London Environment Strategy. Many of the recommendations that LETI put forward to the GLA have been included in emerging London policy and Energy Assessment Guidance:

In 2020 LETI published the Climate Emergency Design Guide, which outlined requirements for new buildings to ensure our climate change targets are met. Supplementary guidance to the Climate Emergency Design Guide, on Embodied Carbon, was provided in the Embodied Carbon Primer.  The Climate Emergency Design Guide has been widely supported, adopted and cited by architects, developers, law makers and built environment professionals across the UK. It has been downloaded over 60,000 times in over 100 countries and its requirements are accepted and followed by building professionals across the UK. LETI is aware of over 30,000 homes and 1,000,000m2 of commercial floor space that are aiming to meet LETI’s new build targets.


In 2021, we published guidance on HydrogenCarbon Alignment, a Client Guide for Net Zero Carbon Buildings and the Climate Emergency Retrofit Guide.


Our Part L Campaign re-evaluates UK regulation and we are continuing to work to develop consensus within UK industry on a definition for Net Zero Operational Carbon. Most recently LETI helped found the new Net Zero Carbon Building Standard in collaboration with the Better Buildings Partnership, BRE, CIBSE, IStructE, RIBA, RICS and UKGBC.

Mission Statement

LETI was established to support the transition of the UK’s built environment to Net Zero Carbon. We do this by:


→  engaging with stakeholders to develop a robust and rapid energy reduction approach, producing effective solutions to the energy trilemma of security, sustainability, and affordability

→  working with authorities to create practicable policy alterations to ensure the regulatory system is fit for purpose, placing verified performance at its core

→  encouraging and enabling collaboration between built environment professionals

→  providing technical guidance to support exemplar developments, enabling pioneers who aspire to go beyond the current regulatory frameworks


1. LETI is focusing on zero carbon as the outcome, but we recognise that reducing energy demand in the first instance is key to achieving a net zero carbon city.


2. The built environment focuses on buildings, but taking a holistic view incorporating the wider infrastructure, from local transport links to the national energy grids, is essential to reduce carbon emissions.


More about LETI’s ethos, vision, code of practice and policies can be found here.


How to get involved

Volunteering for LETI offers an opportunity to learn and progress together, while providing professional development, research skills, and valuable networking. We encourage participants to share the LETI findings in their day jobs and with others- speeding up knowledge and understanding in the built environment industry as a whole.


Subscribing to our mailing list is the best way to keep up to date with what we are doing:

→  Click here to sign up to the LETI mailing list

bottom of page