How to achieve zero carbon estates


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The recent publication from the Climate Change Committee stated that our life-critical 2050 targets will be missed due to a worrying lack of action delivering policies on energy efficiency measures in buildings and “scandalous” policies meaning new buildings built today will still require retro-fitting, according to Lord Deben. Any built environment professional will have seen the signs that retrofitting buildings is the future of the industry.

The aftermath of the nation-wide declarations of the climate emergency in 2019 led to rapid calls for climate action plans for immediate and long-term strategies. This included those responsible for huge estates; from governments, to the NHS, universities, museums, private developers, large companies, schools and the 400+ local authorities who have made climate emergency declarations. 

Positively, for clients looking for a one-off new building or retrofit, as well as direct advice from consultants, there now exists plenty of useful industry guidance from organisations like LETI, RIBA 2030 Climate Challenge, The Passivhaus Trust and AECB

Diagram showing heat loss via roof, walls, windows, floor and ventilation on an existing building. Analysis shows that as much as 30% of heat has been lost through the walls
Decision-making must be led by existing building physics analysis.

Estates face the greatest challenge

But the greatest challenge rests with those responsible for estates of buildings. 

How do you plan the best approach for buildings of different typologies, ages, uses, and conditions? How will you preserve heritage while halving carbon emissions by 2030 and net zero emissions by 2050 across all those different buildings? How much will it cost? And which route will be most effective?

With climate declarations combined with environmental, social, and governance (ESG) targets, it is a highly complex but central task to find your own optimal path to net zero. And as estate portfolios span up to hundreds of properties it is essential for this work to begin urgently to hit these commitments.

Getting to net zero 

For companies targeting net zero, the performance of leased buildings and facilities is critical as these emissions directly contribute to an organisation’s scope 1, 2, & 3 emissions.

Although the premise of net zero assumes offsetting of carbon emissions, it must be our starting point to reduce carbon emissions to an absolute minimum before offsetting residual emissions. Efficiency first is our guiding mantra. Our analysis shows that failure to do this first step not only results in a building that wastes energy but would also need acres of solar panels to achieve net zero. 

Diagram showing the analysis required for understanding how a building performs. Details include roof insulation size, spec and material, as well as details on glazing, floor and various wall types
Understanding the building stock allows a language of intervention options to be developed to inform the retrofit plan

Achieving a net zero city

We have recently concluded an estate-wide evaluation of the City of Edinburgh Council’s portfolio that includes over 300 buildings spanning many use-types, construction typologies, ages, storey heights, and levels of architectural value. The council has an ambitious net zero carbon in operation by 2030 target and needed to understand the optimal pathway for their built assets. Our team developed an EnerPHit informed retrofit plan methodology based on the Passivhaus standard for retrofit. This ensured a rigorous quantitative approach that avoided decisions based on traditional preconceptions. 

The analysis was grounded to the physics of the estate using 12 typical buildings that were forensically analysed as case studies. The structures were fully modelled from 3D point-cloud surveys, tested for airtightness via blower-door tests, analysed for cold-bridging using thermographic imagery, and physically opened-up (where allowable) to better understand their material construction. 

Once the buildings’ existing states were modelled and verified against existing energy meter data, the design team developed intervention options with works to airtightness, insulation, and services, offering energy savings of up to 85% and carbon savings of up to 96%. This analysis looked forward, accommodating the future decarbonisation of the national grid as projected by the BEIS 2032 carbon intensity figures, to illustrate the journey to the wider Scottish target of Net Zero by 2045. This projected forecasting also acknowledged that phasing works on up to 300 buildings will likely take 10-12 years. 

Servicing strategies were developed with engineering partners Harley Haddow and cost implications were explored with Currie and Brown. One example finding from this co-ordinated analysis was that switching existing buildings to air source heat pump technology without doing significant fabric improvements would result in an unrealistically large number of additional radiators and increased energy costs of up to 60%.

For the Edinburgh work, the data points of the 12 case studies were extrapolated across the estates’ 300+ buildings to provide answers to how many buildings required which level of intervention to hit the council’s carbon target, and how much it would cost. Importantly this data also illustrated the projected aggregated financial saving from the operational improvements across the estate. 

Although the national grid is predicted to continue to decarbonise, the financial importance of energy efficiency has rarely been as topical as it is today with energy security and supply issues forcing up fuel bills. Architype are now working with the City of Edinburgh to complete the retrofit works for the first three pilot projects to gain further insight for the rest of the programme. Interest in this work has also led to similar estate-wide retrofit plans being developed for other local authorities.

Graph showing that EnerPHit cuts a predicted 78% of whole life carbon emissions compared to 'business s usual'.
Aiming for a rigorous EnerPHit refurbishment based on the Passivhaus standard can make a huge difference to your building’s lifetime carbon emissions

Understanding whole life carbon

Another key question when deciding how to retrofit an estate is whether to enhance an existing building or to replace it with a new build. For Edinburgh, our Perform+ consultancy team addressed this through undertaking lifecycle analysis of the intervention options using our ECCOLAB software to illustrate that EnerPHit-level interventions would result in lower whole life carbon emissions than a new build. Whole life carbon represents the combination of operational carbon and embodied carbon emissions allowing a holistic view of operational efficiency and constructional impacts. It is also the lens through which the BSI’s recently drafted PAS 2080:2022 advocates for the industry to view projects to drive the built environment’s climate response. 

ECCOLAB’s option-based whole life carbon analysis is well suited to handling the analysis of multiple buildings at varying levels of detail in one workspace. From the IPCC reports we know that the next seven and a half years are critical to mitigating climate change disasters. We simply cannot afford the significant upfront carbon emissions that would result from redeveloping all of the nation’s lesser-performing buildings – time is very rapidly running out.

A new innovative estate version of ECCOLAB is in development that will enable decision makers to model, analyse and optioneer whole life carbon quickly across multiple current and future built assets on estates. Please contact us if you are interested in finding out more about ECCOLAB’s forthcoming estate version.

When retrofit can deliver 78% savings in Whole Life Carbon

Our whole life carbon analysis of the recently completed Entopia retrofit office for the University of Cambridge Institute for Sustainability Leadership demonstrated a dramatic difference in emissions if the rigorous EnerPHit standard was aimed for rather than a business as usual approach. Significant whole life carbon emission savings of 78% will be achieved over a 60-year period through opting for the energy savings of the retrofit Passivhaus standard. Investing in energy efficiency makes a huge difference to cutting carbon and saving running costs, and even more so for estates with a longer-term interest where a building’s energy costs remain the burden of the estate for hundreds of years. Entopia is aiming for world class accreditation standards of EnerPHit, the WELL Gold standard and BREEAM Outstanding to make it not just ultra-energy efficient, but a beautiful building for health and wellbeing, with an emphasis on bio-based materials and extensive re-use during the fit out to further reduce carbon.

Using what you have more before building more 

Another key component to an energy or carbon hierarchy is maximising the utilisation of existing buildings before commissioning new. Not only does this strategy avoid associated costs and environmental impacts, but also avoids taking on future liabilities. Again, a rigorous analysis of spatial use is essential to assimilate an intelligent understanding of current occupancies and frequencies of use. Subjective evaluations often fixate on the instances of high or low utilisation and fail to identify the trends and quantitative opportunities. 

For example, during the development of an integrated zero carbon campus development plan for Plymouth Marjon University, a range of analysis and engagement sessions with all tiers of the university resulted in a utilisation strategy that created flexible, digitally supported, collaborative models of learning and workspace.  As well as driving the university’s approach to excellence in education, the strategy facilitated a 50% increase in student numbers within the existing campus footprint.  This strategy has clear financial and operational benefits as well as minimising the carbon and social impact of the university.

Until recently, utilisation studies were static snapshots from surveys but today’s sensor technology enables real-time usage optimisation, signposting building users to available workspaces and study cubicles, vacant laboratories, or quieter shops.

An estate-wide approach 

Our work on such projects has illustrated that there will always be buildings within portfolios that cannot be improved to the highest performance standards, be it due to listed building or conservation restraints prohibiting certain interventions, the physics of the building fabric limiting the degree of insulation achievable, or its use-type driving an atypical energy demand. These individual buildings with limitations underline the importance of taking an estate-wide approach. This allows for balancing of energy performance across the estate, using buildings that can be extra-high performing to compensate for those that cannot be retrofitted as intensively. For example, through this process, the Edinburgh team were able to outline a pathway to achieving an 80% reduction of energy use intensity on average across the entire estate.

EnerPHit Informed Retrofit plan, showing an 80% reduction in Energy Use Intensity when an EnerPHit retrofit design is chosen
Existing estates can be transformed to industry-leading efficiency levels provided each building plays its part.

Understanding the estate-wide picture accurately is essential before deploying costly improvement works. Otherwise, essential opportunities to retrofit beyond industry-standard targets will be missed, resulting in abortive work, and needing to revisit refurbished buildings to improve their performance a second time. 

UK estate owners hold an exciting position of power and responsibility; with some of the oldest building stocks in Europe and the least developed retrofit policies and subsidies, we have the opportunity to signal a new market direction, ahead of policies, establishing large scale programmes of low carbon, high performance, retrofit works. 

Looking holistically across your estate and finding the optimum path for the planet, occupant wellbeing, the community, and our shared heritage is both a tremendous challenge and a clear opportunity. It is not an easy challenge, but with the right guidance, insight, and action – we can collectively make a difference.


Architype provides retrofit and new build net zero carbon and regenerative architectural design, as well as a specialist consultancy Perform+ that provides strategic insight and guidance, and technical services

For a free one-hour chat about your zero carbon challenges, please contact: