Episode 67:

Hello and Welcome to the Part3 with me podcast. 

The show that helps part 3 students jump start into their careers as qualified architects and also to provide refresher episodes for practicing architects. I am your host Maria Skoutari and this week we will talking about the Low Energy Transformation Initiative aka LETI and their guidance towards net zero carbon. Todays episode meets PC2 & PC3 of the Part 3 Criteria.

So who and what is LETI:

With the constant changes in the environment and building regulations in the construction industry, the voluntary network initially known as London Energy Transformation Initiative aka LETI was established in 2017. Made up of over 1,000 built environment professionals working together to meet the UK climate change targets and support the transition of the London’s built environment to meet Net Zero Carbon. The network consists of developers, engineers, housing associations, architects, planners, academics, sustainability professionals, contractors and facilities managers also receiving support and input from local authorities and other organisations. 

Due to the extensive interest in the initiative, in 2022 the network formed a Community Interest Company and altered their name to what it is know now as, which is Low Energy Transformation Initiative but still known as LETI reflecting their interest in all UK zero carbon policies and regulations not just limited to London. 

Most of their funding is through fundraising to cover their day to day operating costs and they also operate on a voluntary basis for the majority of their activities. 

LETI’s Mission Statement:

Is to engage with stakeholders to develop a robust and rapid energy reduction approach producing effective solutions to the energy trilemma of security, sustainability, and affordability. They also work 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 and providing technical guidance to support exemplar developments, enabling pioneers who aspire to go beyond the current regulatory frameworks.

LETI has developed a number of publications tackling a wide range of guidelines when it comes to net zero carbon policies and the climate emergency which can be found on their website. 

Lets first have a look at their Circular Economy Guidance:

So generally, Circular Economy is an alternative to a traditional linear economy (make, use and dispose), meaning Circular Economy promotes keeping resources in use for as long as possible, extracting the maximum value from them while in use and then recover and regenerate products and materials at the end of each service life. 

Now when it comes to Circular Economy specifically in relation to the built environment, it aims to address the global issues of resource scarcity and environmental degradation. So, LETI promotes following circular economy principles to lower the whole life carbon and as a result addressing the climate emergency. This can be achieved by:

• Retaining the building, system, component or material as fit for purpose to maximise its useful life
• Redevelop through restoring, refinishing and future proofing which is aimed at refurbishment
• Repurposing by redeveloping with significant major changes and replacement of shorter life parts to accommodate difference needs and uses 
• Deconstructing and retaining a buildings elements, systems and components as much as possible 
• And Remanufacturing and recycling when materials are at end-of-life to be made to products, materials or substances. 

LETI suggests that in order for the world to meet its net zero carbon future we must set climate change targets that are Scalable, Achievable, Verifiable and Whole Life. And LETI recommends that by 2025 100% of new buildings should be designed to deliver net zero carbon.

Now lets move on to Whole Life Carbon and how it can be achieved to meet LETI’s milestones. Whole Life Carbon is primarily formed by two key components:

1. Operational Carbon: Meaning a building that does not burn fossil fuels and is 100% powered by renewable energy achieving a level of energy performance in-use in line with the national climate change targets. Operational carbon is essentially the energy consumed by a building associated with heating, hot water, cooling, ventilation and lighting systems, as well as equipment such as fridges, washing machines, TVs and so on.
2. Embodied Carbon: Meaning best practice targets for embodied carbon are met and a building is made from re-used materials and can be disassembled at its end of life in accordance with circular economy principles. Embodied Carbon as a term, means the ‘upfront’ emissions associated with building construction including the extraction and processing of materials and the energy and water consumption in the production, assembly and construction of the building. Embodied Carbon also included the ‘in-use’ stage and the ‘end of life’ stage and any transportation relating to them. 

So looking at Operational Carbon in the first instance, new buildings can meet the targets by installing roof mounted PV panels for example or for taller buildings they may invest in additional renewable energy off site. But as well as achieving net zero carbon on a building level, it is important the balance is also achieved at a national level meaning developments must not exceed their ‘energy budget’ which LETI sets as an Energy Use Intensity target. This target is an annual measure of the total energy consumed in a building. LETI believes that setting an EUI requirement for new buildings is fundamental to meeting the climate change targets. It is a good indicator for building performance as the metric is solely dependent on how the building performs in-use; rather than carbon emissions, which also reflect the carbon intensity of the grid. EUI is a metric that can be estimated at the design stage and very easily monitored in-use as energy bills are based on kWh of energy used by the building. This metric can be used to compare buildings of a similar type, to understand how well the building performs in-use and it includes all of the energy consumed in the building, such as regulated energy (heating, hot water, cooling, ventilation, and lighting) and unregulated energy (plug loads and equipment e.g. kitchen white goods, ICT/AV equipment). EUI can be expressed in GIA (Gross Internal Area) or NLA (Net Lettable Area). 

Now moving on to Embodied Carbon, buildings can meet this target by considering how resources on a building can be used at the end of its life and looking at the building as a ‘material resource bank’. So new buildings should re-use materials and products from demolished buildings and also be designed to be disassembled in the future so that materials and products within the building can be re-used again in future buildings. 

Then you have the secondary elements which is the Future of Heat, Demand Response and Data Disclosure.

• Future of Heat is the decarbonisation of heating and hot water.
• Demand Response is integrating demand response and energy storage into buildings allowing buildings to be flexible with their demand on the grid. 
• And Data Disclosure is understanding how buildings perform in-use through post occupancy evaluation.

So as mentioned whole life carbon is primarily formed by operational and embodied carbon, therefore, whole life carbon incorporates all carbon emissions that arise as a result of the energy used in the construction operation, maintenance and demolition phases of a building. Therefore, a whole life carbon building is one that meets the operational zero carbon balance and meets best practice targets for embodied carbon including upfront embodied carbon targets, proportion of materials that are from re-used sources and proportion of materials that can be re-used in future buildings, an item to bear in mind is when construction, transport and disassembly is carried out with renewable energy there will be zero carbon emission associated with the embodied carbon. 

To meet these requirements and move towards a net zero carbon future, LETI suggests that significant upskilling is required in the construction industry specifically towards:

1. Energy modelling in relation to fabric performance and system selection 
2. Designing, whereby the whole design team understands and develop their contributions towards reductions of operational energy and embodied carbon in a cost effective way
3. Constructing, requiring contractors to learn how to construct buildings meeting the whole life carbon requirements
4. Operating and facilities management, whereby they understand and reduce energy consumption to been operational carbon requirements 
5. Updates to Building Regulations to meet climate change targets 

So how can Clients, Policymakers and Designers contribute respectively towards adopting and promoting Operational Energy, Embodied Carbon, the Future of Heat, Demand Response and Data Disclosure. 

1. Starting with Operational Energy:

Clients should make the key decisions in:

• Committing to a net zero carbon vision and moving towards achieving this goal.
• Appointing key design team members to influence operational energy performance outcomes early in the design process.
• Committing to energy benchmarking exercises and set established performance targets early in the design process - (RIBA Stage 2).
• Ensuring that life cycle cost analysis and whole life carbon analysis are carried out for all projects
• Committing to disclosure of regulated and unregulated building energy consumption at both design and operation stages.
• Issuing briefing documents that set out targets aligned with this guidance document.

Policymakers should then put together a strategy, whereby they:

• Request disclosure of key building performance metrics prior to planning approval. Then evaluate performance against LETI archetypes (which are Small, medium and large scale residential, commercial offices, and schools) and request clarification where targets are not being met.
• Establish expertise within planning departments that are capable of assessing adherence to the key performance metrics.
• Establish suitable requirements via Supplementary Planning Guidance
• Apply equal or greater weighting to building operational performance than to aesthetic considerations in the overall context of the design, pre-application and determination process.

And then Designers can proceed in implementing the Client requirements and Policymakers strategies by:

• Producing net zero operation pathways for projects in design
• Design in accordance with the recommended key performance targets for each building archetype.
• Ensure that design decisions reflect the energy hierarchy 
• Design to recommended heating and hot water coefficients of performance (COP)
• System design to be carried out with consideration of both regulated and unregulated energy end uses.
• Dedicate resources to staff learning and development to improve familiarity with key terminology and influence on building energy performance.

1. Now moving to Embodied Carbon:

Clients should make the key decisions in:

• Clarifying their goals for Net Zero and Circular Economy developments that embrace embodied carbon reductions. 
• Developing financial structures within the business for allocating funds across R&D/pilot projects.
• Identifying employees across the business who will be responsible for Net Zero, circularity and embodied carbon performance outcomes.
• Specifying in the project brief that the development will have low embodied carbon, adopting the principle of reuse and refurbish over new build and requiring a comprehensive embodied carbon reduction strategy.
• Stipulate embodied carbon performance targets.
• Appointing a design team with experience of conducting embodied and whole life carbon analysis.
• Specifying in the contract that the principal contractor will monitor and report ‘as-constructed’ embodied carbon showing compliance with embodied carbon performance targets.

Policymakers should then put together a strategy, whereby they:

• Adopt a policy hierarchy that advocates circular economy principles: reuse and refurbishment in preference to demolition and new construction.
• Adopt a policy that mandates embodied carbon reduction strategies based on embodied carbon and whole life carbon analysis on all projects.
• Adopt embodied carbon targets.
• Recognise a consistent methodology and dataset for embodied and whole life carbon analysis through the creation of a national embodied and whole life carbon database.
• Include requirements on embodies and whole life carbon in building planning and approval frameworks with consent being dependent on the reporting of performance against the design stage target.
• Request Reduction Calculations.
• Phasing in the mandatory requirement of Environmental Product Declarations for at least all building parts forming substructure, frame and upper floors.

And then Designers can proceed in implementing the Client requirements and Policymakers strategies by:

• Adopting the circular economy principle of reuse and refurbish before new build and ensure carbon analysis is integrated into scope of services and design programme.
• Upskilling the design team to develop in-house capabilities and understanding of embodied and whole life carbon reduction principles and ‘big wins’.
• Implement embodied carbon as a sustainable design metric and calculate embodied carbon emissions of all projects.
• Request Environmental Product Declarations (EPDs) from all suppliers.

2. Next, moving to the Future of Heat:

Clients should make the key decisions in:

• Highlighting the need for passive heat gain, resulting in smaller, simpler heating and hot water systems.
• Prioritising reduced fabric heat loss so that incidental room heat gains can become primary heat sources.
• Mandating cost savings from reduced heat systems, improve building fabric and reduced hot water demands.
• Requiring reduced occupant fuel bills, both for energy consumed and associated systems service charges.
• Reducing room small power requirements to reflect Smart ICT fit-out and in-use 

Policymakers should then put together a strategy, whereby they:

• Set locally specific overall performance criteria 
• Require the same building fabric energy standards for all buildings in anticipation of potential future change of use. 
• Prescribe the capture of waste heat to make it available to other via heat sharing networks.
• Prepare example planning submissions for a selection of building types demonstrating net zero carbon solutions.
• Ensure all district heating networks have roadmap to 2030 zero carbon in place.

And then Designers can proceed in implementing the Client requirements and Policymakers strategies by:

• Using the LETI Heat Decision Tree at concept design stage and again at developed design stages provided in the Climate Emergency Design Guide.
• Use high levels of thermal insulation and airtightness for all building types to limit the installed peak heat loss.
• Limit the installed peak capacity of domestic hot water (DHW) heating plant.
• Use European Water Label (EWL)ii ‘Green’ rated outlets for domestic hot water and ensure a maximum 1 litre volume limit in dead-legs.
• Select system designs that smooth out peak demands to help ease grid capacity constraints and reduce required installed capacity.

3. Next, moving to the Demand Response:

Clients should make the key decisions in:

• Investigating the potential for energy flexibility in developments.
• Consider rising energy costs and the potential for an energy flexible building to take advantage of dynamic pricing in the electricity market. 
• Be willing to invest more on control systems and metering to build ‘future ready’ energy systems in developments.
• Set a brief that allows for flexibility in meeting comfort bands. 

Policymakers should then put together a strategy, whereby they:

• Require energy flexibility assessments on all schemes.
• Allow for carbon saved from energy flexibility to contribute towards the sustainability requirements on a scheme 
• Set binding targets for minimum energy flexibility to be achieved in medium to large scale developments.
• Develop an auditing mechanism to ensure compliance and verification.

And then Designers can proceed in implementing the Client requirements and Policymakers strategies by:

• Considering the periods during the day and throughout the year that the development uses electricity
• Learn about dynamic carbon factors and consider them in energy and carbon models.
• Develop and use tools to model flexibility in the energy systems and calculate carbon reductions.
• Specify high accuracy/resolution metering in the right places to prove when an energy-use change has occurred

4. And lastly, looking at Data Disclosure:

Clients should make the key decisions in:

• Reporting against operational energy targets following completion.
• Include central collection and collation of sub-metered energy data in the project brief.
• Use a central data store and a private online data platform for collating, presenting and interrogating building or asset energy data.
• Uploading aggregated energy data to a publicly available and open source data platform.
• Consider a Display Energy Certificate (DEC) assessment annually as a reliable energy reporting framework.
• Specify a breakdown of energy consumption by use types that are specific and relevant to the organisation, for example space heating, hot water and split between landlord and tenants..

Policymakers should then put together a strategy, whereby they:

• Provide an open source and public platform for sharing energy data on all buildings. Collaborate with authorities and institutions to use existing resources as a basis for developing a robust and flexible platform.
• Post process shared energy data using annual average carbon factors to provide reliable and comparable carbon emission information for each building. 
• Mandate operational energy ratings and energy disclosure for new buildings for a period of at least five years.
• Enable and encourage continued reporting of energy consumption data for existing buildings, through automated reporting.
• Review Display Energy Certificate benchmarks and guidance.

And then Designers can proceed in implementing the Client requirements and Policymakers strategies by:

• Identify the outcomes that will be monitored and ensure the metering strategy can achieve this.
• Specify, design, commission and document sub metering to suit the size and use of the building, to allow identification and diagnosis of problems, and to give a breakdown of consumption by use type.
• Use a dedicated data store to save energy consumption information.
• Prepare a building Log Book at handover.

So what are the implementations from these aspirations from clients, policymakers and designers to achieve net zero carbon:

1. From an operation energy perspective:

First step, would be setting regulations which are clear, measurable and indicate a pathway to 2030 by setting a series of absolute Energy Use Intensity targets for space heating, hot water and overall energy demand for both retrofit and new builds. Measuring building performance in terms of energy, actual performance measurements and post completion compliance. Mechanical ventilation with heat recovery (MVHR) should be the default ventilation system in all new buildings to reduce heat loss through ventilation and improve indoor air quality and Local authorities should be encouraged to move beyond statutory building regulations and set energy consumption limits ensuring energy efficiency measures are prioritised over on-site renewables. The energy a building requires to operate should be matched by the amount of renewable energy that can be made available to that building. 

2. From an embodied carbon perspective:

We should build less new builds and increase refurbishments and re-use, build lighter structures, build with longevity and local context in mind, build low carbon by reviewing material specifications, assess end of life and adaptability and build collaboratively. Procurement can be a way of promoting carbon to become a measurable aspect of the specification and embedding it into the contract.

3. From a Future of Heat perspective:

Implementations should be made in significantly reducing heat demand through the development of more efficient building fabric and hot water use, and reuse of low temperature waste heat sources. Domestic hot water use reduction is especially important because of the adverse energy and carbon implications of delivering the higher temperatures for the hot water compared to space heating systems. Reduction in heat loss is also key and LETI recommends this can be improved through the reduction of glazing in buildings to reduce winter heat loss and summer cooling. The next priority should be harnessing waste heat from all available sources in and around the site which can then be redistributed contributing to meeting energy demands or through heat sharing from others.

4. From a Demand Response perspective:

In order to reduce building energy use and carbon emissions, LETI recommends that each building should be required to undertake an energy flexibility assessment which would record their total kW of energy available that can be controlled and how long the demand can be reduced or stored for on a per building basis, but in order for this to be possible an industry key performance indicator metric needs to be developed allowing energy flexibility to be set at the design stage of a development. Also having a high performance building fabric will assist with the reduction of energy demand as it will maintain the internal temperatures at comfortable levels without requiring cooling or heating. Also the use of battery systems can assist through storing excess electricity generated reducing the demand on the national grid. 

5. And lastly from a Data Disclosure perspective:

Building designers and developers should start compiling building energy monitoring data to better understand how building perform at post-occupancy. All new project should, therefore, should include a metering strategy and central repository to ensure future public energy reporting is simple to implement. Once enough data has been publicly publicised and made available and usable to everyone, building owners and occupiers will begin to see the value in reporting and using this data to inform their use decisions. 

To reinforce the contributions to be made by Clients, Policymakers and Designers in adopting net zero carbon, LETI has also put together an Actions by RIBA Stage Checklist:

At Stage 0, LETI recommends that:

• A net zero carbon champion is identified
• Project team responsibilities should be identified to achieve operational energy use targets 
• Contractual incentives should be considered for achievement of performance targets.
• A project team member should be identified who can advise on demand response.

At Stage 1, LETI recommends that:

• Clear intent for zero carbon targets is set and define what this includes, document boundaries and targets
• An energy use intensity target should be set and embedded within the brief
• Localised energy constraint issues should be discussed with DNO
• Eligible demand response programmes at a national and regional scale should be identified 
• Data disclosure into BIM requirements should be incorporated

At Stage 2, LETI recommends that:

• Clear energy use targets, document targets and strategies to achieve this should be established 
• The concept design should be developed in accordance with critical design parameters including: 
• Building orientation
• Building form factor
• Facade glazing ratio
• Likely occupancy patterns and operating scenarios
• Facade glazing ratio
• Technical systems integration.
• Then a preliminary operational energy model  should be developed to aligned to the Energy Use Intensity targets. 
• The LETI Future of Heat Decision Tree should be used when making decisions on heating and hot water systems.
• Implementing the most significant carbon/energy reduction measures in design including demand response and energy storage opportunities.
• Highlighting the roles and opportunities for overcoming performance gap.

At Stage 3, LETI recommends that:

• The full operational energy model for evaluation of predicted energy demand is refined.
• Proposed design changes are tested using the energy model.
• Detailed targets and strategies to achieve these are updated and documented. 
• Ensure proposed construction details are robust to support low energy and airtightness performance characteristics.
• Ensure that the risk of overheating has been assessed and mitigated.
• Develop demand response strategy and simulate potential impact.
• Develop sub-metering strategy using LETI energy disclosure guidance. 
• A secure remote source for metered data to be transmitted over a communications network for aggregation and storage should be established.

At Stage 4, LETI recommends that:

• The building energy model should be updated with the latest design amendments, and ensure that operational energy targets are still being achieved.
• The envelope specification should be confirmed and detail design should be completed, ensuring good continuity of insulation and airtightness.
• Check the suitability of the heating and hot water system using the LETI Future of Heat Decision Tree.
• Iterate demand response model with exact design data to gain a more accurate prediction of carbon savings and monetary gains. 
• Ensure specified metering is incorporated.
• Include operational energy targets in the construction tender package
• Incorporate in contractors’ prelims with guarantees to recalculate energy model if items in the register are changed or value engineered, to demonstrate that ‘as built’ project meets agreed operational targets.

At Stage 5, LETI recommends that:

• Where possible, the appointment of a clerk of works is responsible for quality checks should be ensured.
• The energy model should be updated to account for any changes in the design or assumptions behind it and reject substitutions and omissions if achieving performance targets may be compromised by the changes.
• Engage with the supply chain regarding the design targets of the project and where possible provide toolbox talks to help upskill contractors and to communicate the importance of quality construction.
• Ensure the contractors understand commissioning requirements, including metering commissioning and validation of manual vs half hourly readings.
• Ensure the contractor has quality monitoring processes in place to ensure proper installation of insulation, airtightness layer and mechanical equipment for the whole of the construction period.
• Carry out benchmark inspections to clarify quality expectations and continue to monitor construction quality, including in-situ thermal performance tests, thermographic and air tightness testing.
• Ensure the contractor understands the commissioning requirements.

At Stage 6, LETI recommends that:

• The final construction should be reviewed including rectification work, for quality, including in-situ thermal performance tests, thermographic and air tightness testing.
• Finalise the as-built energy model to account for any changes in the design or assumptions behind it.
• Commissioning and testing to be fully completed and witnessed and that the ‘as installed’ controls strategies, setpoints, commissioned flow rates, metering etc. are in line with the energy model.
• Ensure the building user is trained and understands use of the building systems.
• Ensure that planned demand response activities occur correctly as part of the commissioning process and that the initial setup parameters are recorded.
• Ensure a suitably qualified individual understands the energy management and measurement systems.
• Ensure that performance data from sensors and meters are reconciled with the main meter, spot meter and BMS readings and that logs are set up in BMS to facilitate long term monitoring of building performance.

And at Stage 7, LETI recommends that:

• For the first year of occupation both the building and the targets should be tuned to actual building usage patterns.
• Ensure hourly energy consumption trends match operating hours.
• Ensure the metering system is operating correctly and is regularly validated against utility meters.
• Identify and track key efficiency metrics. Aim to track the fewest but most useful metrics.
• Assign an annual budget for monitoring energy use and tuning controls in response.
• Line up energy efficiency assessments with post occupancy evaluation assessments to ensure occupant satisfaction with conditions in the building.
• Upload total energy and heating energy consumption data to a public data platform for the first 5 years post-completion.

So the outcome of these implementations is for all new buildings to:

• Have low energy use and use the Total Energy Use Intensity targets 
• Efficient building fabric to reduce space heating demand 
• Measurement and verification of annual energy and renewable energy generation 
• Assessment and reduction of embodied carbon and verified at post-construction 
• Maximising the use of renewable energy sources and to be used for heating and hot water
• Reporting of the average annual carbon content of heat supplied to the building
• Energy demand response and storage measures should be incorporated and peak energy demand to be reported
• A carbon balance calculation should be undertaken demonstrating the building achieves net zero carbon balance
• And any energy use not met by on-site renewables should be met by an investment into additional renewable energy capacity off-site or through a minimum 15 year renewable energy power purchase agreement.
• Whole Life Carbon is primarily formed by two key components, Operational and Embodied Carbon, with the Future of Heat, Demand Response and Data Disclosure as secondary elements to achieving whole life carbon.

So to sum up what I discussed today:

• 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.
• LETI’s Mission Statement is to engage with stakeholders to develop a robust and rapid energy reduction approach producing effective solutions to the energy trilemma of security, sustainability, and affordability.
• LETI promotes following circular economy principles to lower the whole life carbon and as a result addressing the climate emergency.
• To achieve their targets, LETI has put together a road map following the RIBA Stages promoting whole life carbon adoption by the construction industry 
• New buildings should be designed with low energy use in mind, measurement and verification, reducing construction impacts, low carbon energy supply and zero carbon balance