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LETI is a network of over 1,000 built environment professionals, working together to put the UK on the path to a zero carbon future. The voluntary group is made up of developers, engineers, housing associations, architects, planners, academics, sustainability professionals, contractors and facilities managers.


24.03.17 Future Homes + Building Standard Consultation response is out NOW!


Thanks to YOUR support, time, expertise, engagement and contribution, we have now released the LETI consultation response and the LETI evidence base!

Thank you for sharing LETI key messages, thank you for those who volunteered their time, thank you for those who submitted evidence, thank you for those who donated.

From all of us at LETI - A HUGE THANK YOU TO ALL OF YOU!

→  Find out more

24.03.06 Future Homes + Building Standard Consultation response deadline EXTENDED!

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The Future Homes + Building Standard Consultation deadline has been EXTENDED!

LETI's response to the Future Homes Standard Consultation is almost ready! Now you have even more time to help make our voices heard and meet our climate commitments!

The consultation will onw close on the 27th of March but time is still critical, check out our consultation response toolkit and respond NOW!

→  Find out more

24.02.20 Future Homes + Building Standard Consultation response toolkit goes live!

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More than three years has now passed since the Part L 2021 consultation. The Government's decision to ban fossil fuel based energy is evidence that responding to this previous consultation was worth the amazing collective effort.

The government have now released the Future Homes and Buildings Standards: 2023 consultation.  While we welcome an end to the use of fossil fuels, we believe these proposed changes do not go far enough. 

LETI have produced a consultation response toolkit to the Future Homes and Building Standard Consultation.  Now, we need your help to make our voices heard and meet our climate commitments!

→  Find out more

24.01.31 A LETI thank you for all your donations!

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On 31st January 2024 our crowdfunder successfully raised £15,360 with the help of 86 generous supporters!  A huge LETI thank you to everyone who donated, your support and contributions are very gratefully received and will ensure 2024 is our best year yet!

If you missed out on donating - don't worry, you can still support the work we do. Why not get involved and volunteer with us?

→  Find out more

24.01.24 Future Homes Standard & Future Building Standard 2023 | LETI Key Messaging Webinar

Join our webinar!

Capitalising on the great work done in 2019 and 2021, LETI is currently developing a coordinated response to the Future Homes Standard & Future Building Standard 2023 Consultation, which covers proposed changes to Part L (conservation of fuel and power), Part F (ventilation) and Part O (overheating) and the new Home Energy Model (HEM).

Join us from 1-2pm on Tuesday the 20th of February for a lunchtime webinar where we will share our key messaging related to the consultation. Register below to join the discussion.

By responding to this consultation, we have an opportunity to have our voice heard and positively influence the impact our building can have on the environment.

→  Register here

22.01.24 The Future Building Standard - help shape LETIs key messaging

We need your help responding!

As we are sure you are aware the Future Homes Standard & Future Building Standard 2023 Consultation was released in December with responses due on the 6th of March.

We need your help to promote our key messaging and coordinated response to the Future Homes Standard and Future Building Standard 2023 Consultation.
We are looking for volunteers to cover the following roles in the run up to the consultation deadline, who have availability between the beginning of February and the 6th of March. We need your support for the following roles:

  • Communications lead

  • Press Lead

  • Graphics Lead

  • External organizations coordinator 

If any of these roles are of interest to you, please register your interest to volunteer. We really value the contribution of all our LETI volunteers and could not achieve what we do without you. Thank you!

→  Register your interest

30.11.23 LETI Christmas Showcase + Fundraiser 2023!

LETI Christmas Showcase + Fundraiser 2023!

Hosted by Feilden Clegg Bradley Studios in London, LETI celebrated 2023 with an evening showcasing all the fantastic work we have been involved in throughout the year, what 2024 will hold and how you can get involved.  Thank you to everyone who joined us to raise a glass to all the amazing LETI volunteers and for all your generous donations! 

We are still fundraising and your financial support is incredibly important to us. It enables LETI to have more impact and plan more ambitiously for the future.  We believe that LETI’s collective voice has had a significant impact over the last six years and we would like this to continue. If you agree, please donate what you can and support us!

→  Donate here

22.08.23 LETI Embodied Carbon case study call out!

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The LETI embodied case study group is calling for further case studies for future publication.  Case studies allow LETI to evolve and link the information gathered to other emerging industry declaration databases to bring more transparency to embodied carbon reporting and practice.
We are currently looking for new applications for potential new embodied carbon case studies.  If you have a project in mind and would like to register, get in touch by filling out our online form!

→  Find out more here

14.04.23 LETI Operational Modelling Guide

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13.03.23 LETI Specification and Procurement Guide

This modelling guide explores how a building's meter readings can be estimated at design stages, and how this understanding can be used to inform and improve designs, enabling more confidence that operational energy targets can be achieved.  This guide will be a useful resource for all stakeholders involved or interested in delivering net zero operational carbon projects.


The guide addresses why we need to use operational energy performance modelling, and the key pieces in the jigsaw needed to make it effective for any project.

→  Download the Operational Modelling Guide here!

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This guide has been created to support designers and Contractors who are facing the difficult task of trying to reduce embodied carbon without a clear roadmap to follow.


The Low Embodied Carbon Specification and Procurement guide is intended to support that process by considering specification and procurement in more detail, thereby helping to reduce the embodied carbon performance gap between the design intent and the reality of construction. This follows on and links to the LETI Embodied Carbon Primer, which was created to help designers make embodied carbon reduction strategies on projects.

→  Download the Embodied carbon Specification and Procurement Guide here!

06.03.23 LETI Unpicker - Retrofit vs Rebuild

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In our most recent publication update, LETI have today published a document that provides guidance on how to compare whole life carbon for a retrofit, versus its demolition and rebuild. This document aims to help review whole life carbon comparisons between rebuild and retrofit scenarios, to answer the following question:


Does the whole life carbon assessment and comparison provide a basis for decision on the carbon part of the retrofit versus rebuild argument?  


To answer this, the Retrofit vs Rebuild Unpicker helps establish whether the assessment and comparison are as fair and like-for-like as possible, technically robust and transparent.

→  Download the Retrofit vs Rebuild Unpicker here!

20.02.23 LETI opinion piece: Operational Carbon in Whole Life Carbon Assessments

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LETI have published an ‘opinion piece’ that proposes a ‘split carbon factor’ methodology for the conversion of operational energy into operational carbon, for the purpose of making design decisions in buildings.


Operational and embodied carbon emissions are interrelated, central to these complexities are uncertainties around the decarbonisation of the UK electricity grid, alongside the interdependence of the amount of energy used by buildings and the ability of the UK grid to decarbonise.


In this method, a decarbonised carbon factor is applied to the electricity consumption that is below a LETI Energy Use Intensity (EUI) target, and a non decarbonised carbon factor is applied to electricity above a LETI EUI target.

→  Download the opinion piece here!

10.01.23 LETI Presents: Whole Life Carbon webinar series 2023!

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Join us for the new LETI webinar series introducing the concept of Whole Life Carbon and how we in the industry can urgently reduce carbon emissions within the built environment. 


Beginning on the 24th January 2023 and running until mid July, the WLC webinar series will be delivered by a wide variety of speakers and cover a range of relevant topics from operational energy modelling to embodied carbon specification and procurement.  A number of the webinars will also be accompanied by the presentation of the many new 2023 LETI publications.


Delivered every 2-3 weeks on a Tuesday (1-2pm), the webinar series will provide a co-ordinated training programme which will help you on your WLC literacy journey!


The first three sessions are open for registration:


       24th January - Introduction to Whole Life Carbon and the LETI webinar series

       7th February - Embodied Carbon case studies

       21st February - Operational Carbon in Whole Life Carbon assessments

→  Book your tickets now!

09.01.23 LETI launches Embodied Carbon Case Studies

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The LETI Embodied Carbon Case Studies are a selection of projects in the UK chosen to showcase good practice regarding consideration of embodied carbon and whole life carbon principles in a clear, and consistent format. The aim of their development has been to create a format, with a clear and understandable scope, to provide a useful means of sharing lessons learned to reduce embodied carbon while striking a balance of reporting robust metrics to back up the ‘carbon story’ behind the analysis and project procurement.

The template on which they are based has been aligned where possible to the RICS PS Whole life carbon assessment for the built environment reporting format, and the emerging GLA Whole Life Carbon Reporting template, the UKGBC Net Zero Carbon Construction Reporting Template, with input from LETI Embodied Carbon Working Groups.

→  Download the Embodied Carbon Case Studies here

02.12.22 LETI opportunities for 2023

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We are delighted to announce that LETI has a new secondee and operations programme for January 2023, an exciting opportunity for passionate individuals to become a part of the expanding LETI contributor team. 

Application Deadline: Wednesday 14th December 2022

→  Read the full role descriptions here

25.10.22  LETI adapts name to reflect relevance across UK

Since its inception in 2017, LETI has rapidly grown from a small-scale London-based group to over 1000 built environment professionals across the UK, providing consensus-based guidance for the construction industry. As LETI expands and engagement increases across the UK, we recognise the importance of emphasising our UK-wide relevance. Discover more about LETI's transition from away from its previous name, becoming a Community Interest Company and joining the SDF Alliance.

→  Learn more

25.05.22  UK Net Zero Carbon Building Standard


LETI are excited to be part of a cross-industry group developing the UK’s first Net Zero Carbon Buildings Standard. If you missed the project launch event, you can now catch up on the webinar recording and download the presentation slides to find out more about how you and your company can get involved:

→  UK Net Zero Buildings Standard: Get involved

26.04.22  LETI launches Circular Economy 1-Pager

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LETI's one page summary from the Circular Economy Workstream provides a definition and explanation of what circularity in a built environment context comprises, a circular strategies hierarchy, primary actions for the built environment industry to prioritise, and suggests key circularity metrics for professionals to test. The summary also references the relationship between circularity and whole life carbon reductions which requires further attention.

→  Download Circular Economy 1-pager

14.03.22  What does Net-Zero mean? Launch of CIBSE-LETI FAQs

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The Net-Zero FAQs build on the work of the Whole Life Carbon Network/ LETI definitions, with simple explanations on the implementation of Net-Zero in practice and in detail. It is an exciting new resource developed jointly by CIBSE and LETI, and supported by others in the industry including the RIBA. These FAQs have been developed since the industry consultation that we ran in November 2021 - thanks again to those of you that took part. Get your questions ready and join us for the official online launch of the CIBSE-LETI FAQs on Thursday 7th April at 16:00.

→  CIBSE-LETI Net-Zero FAQs launch

16.12.21  LETI Opinion Pieces

We are launching a new type of publication, the LETI Opinion Piece, a discussion document on a specific topic that presents a point of view in time and hasn’t necessarily been through the full LETI peer review process. LETI’s first Opinion Piece looks at how circular economy and carbon in construction are linked. It shines a light on the interconnectedness of these two concepts and highlights interrelated issues, synergies and challenges when trying to meet the requirements of both the circular economy and reducing carbon.

→  Download the Circular Economy & Carbon in Construction Opinion Piece

15.11.21  LETI / CIBSE: What is Net Zero? FAQ Consultation


In May this year LETI released carbon definitions that provide clarity on terminology in collaboration with the Whole Life Carbon Network, supported by the RIBA. This document provides clarity on net zero carbon-operational energy, net zero embodied carbon etc. The next step is getting into the details on this. CIBSE and LETI are now working together to produce a set of FAQs on the definitions, to make sure the definitions are applied consistently in as many real-life situations are possible, and that they deliver the right outcomes. We are seeking your views on these FAQs – please download the PDF below to view the draft FAQs, (they also include the survey questions), once you have read these please complete the consultation survey here.

Consultation survey deadline: Sunday 28th November

→  Download What is Net Zero - FAQs & survey here

15.11.21  LETI at COP26: Highlights

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COP26 has come to a close, and although it may have not been the outcome we were hoping for, we had a really positive 2 weeks. Thank you to everyone who attended the events and workshops we were involved in. Check out our Gallery page below for our COP26 highlights including Geovation Net Zero event, CIBSE/ LETI What does Net Zero mean?, Open House event: LETI Climate Emergency Retrofit Guide​, LETI takeover Construction Scotland Innovation Centre.

→  Visit our Gallery page for LETI at COP26

01.11.21  COP26: LETI Activities

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COP26 is here! We have created a round-up of LETI COP26 activities for you, as well as other key COP26 activities from other organisations. Don't miss an exciting programme of presentations, debates and workshops and learn more about how to put your climate pledges into action in the transition to a net zero built environment!

→  Discover LETI COP26 activities here

21.10.21  LETI launches Climate Emergency Retrofit Guide

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Following the publication of the Climate Emergency Design Guide for new build in January 2020, LETI has gathered together experts from across the construction industry including Passivhaus Trust, ACAN, RIBA, CIBSE and the AECB to provide a blueprint on how to retrofit our existing domestic buildings.


By examining the upgrade of the UK housing stock and summarising what can be achieved, The Climate Emergency Retrofit Guide sets out what good retrofit looks like, and advises on how to deliver efficient, resilient and healthy homes. This includes defining energy use requirements, as well as highlighting the potential risks of poor retrofit.

→  Download Climate Emergency Retrofit Guide here

14.10.21  LETI Wins AYA Leadership Award

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LETI are delighted to have been awarded a Building Design Architect of the Year Award for Architectural Leadership. Congratulations to everyone who were nominated and won awards. We are proud to be recognised for building "a credible cross-industry network influencing policy and creating practical guidance. The judges said LETI has had considerable traction with clients and as a result was responsible for effecting real change."

30.09.21  LETI Climate Emergency Retrofit Guide Launch

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Following the publication of the Climate Emergency Design Guide for new build in January 2020, LETI has gathered together experts from across the construction industry including Passivhaus Trust, ACAN, RIBA, CIBSE and the AECB to provide a blueprint on how to retrofit our existing domestic buildings.


By examining the upgrade of the UK housing stock and summarising what can be achieved, The Climate Emergency Retrofit Guide sets out what good retrofit looks like, and advises on how to deliver efficient, resilient and healthy homes. This includes defining energy use requirements, as well as highlighting the potential risks of poor retrofit.

Please join us for an engaging and insightful online launch of the new guidance on Thursday 21st October 10:00 - 11:30 and put your burning questions to our expert panel. 

→  Register for the Climate Emergency Retrofit Guide Launch here

11.08.21  LETI Client Guide for Net Zero Carbon Buildings

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As our global community struggles to keep up with their growing climate commitments, the LETI Client Guide for Net Zero Carbon Buildings will help all construction clients navigate their way through a rapidly changing construction industry. It pulls together key details from numerous LETI documents and publications, which cover the ways in which briefing, designing, procuring, constructing, occupying, managing and valuing buildings must change.

→  Download the Client Guide for Net Zero Carbon Buildings here

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Industry experts, across the value chain, have offered LETI an insight into their thoughts and views on embodied carbon and how this is being managed through procurement. Supporting LETI guidance will be published this year, but if you would like a preview of the findings, please view our 2020 Specification & Procurement Survey analysis.

→  Specification & Procurement survey analysis

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Net zero performance should include the consideration of embodied and whole life carbon but in order to do this we need to combat a lack of consistent measurement leading to mis-aligned benchmarks, project targets and claims. Following the release of the Embodied Carbon Primer in 2020, LETI has been consulting with industry groups, including RIBA, IStructE, the Whole Life Carbon Network and more, to help resolve these inconsistencies. From these discussions, LETI has launched a suite of 4 documents that should be read together, along with the net zero operational one pager, to understand operational, embodied and Whole Life Carbon and how to achieve a net zero.

→  Download the publications here

Get involved in LETI

There are many opportunities to support LETI, including volunteering your time and expertise. 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

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