Guide to developing a Decarbonisation Plan
This webpage guides you through the process of creating a Decarbonisation Plan.
It is written for cultural and heritage organisations that own, manage or occupy historic buildings, whether they are listed or not. It is also useful for anyone responsible for commercial heritage buildings, whether privately owned or in the public sector, as well as built environment professionals who may be commissioned to undertake this work.
Why decarbonisation matters
Buildings are a major source of greenhouse gas emissions. Emissions come from the manufacturing processes and the materials used in construction, as well as the energy used in daily operation: heating, cooling, lighting, and other services.
Climate change is putting increasing pressure on the buildings we care for. Rising temperatures and more extreme weather events pose growing risks to buildings and their occupants, and this has the potential to increase the energy use required to maintain healthy indoor environments.
In this context, there is an urgent need to adapt or upgrade (‘retrofit’) our existing buildings. This means using less energy, improving resilience to climate risks, and transitioning fossil fuel sources to low carbon alternatives.
Why historic buildings need a tailored approach
There are many ways to improve the energy efficiency and climate resilience of a historic building. However, the need or opportunity to do so will vary widely, depending on the building and its context. In the cultural and heritage sectors, opportunities may be affected by:
- Listed building or conservation area heritage designations
- Complex or divided ownership and management structures
- Limited budgets for both maintenance and repair, and capital works.
About this guide
In 2025, Historic England (HE) and Arts Council (ACE) commissioned Haworth Tompkins to carry out a Pilot Study on the Decarbonisation of the Cultural and Heritage Sector. They worked with engineers Skelly & Couch, building surveyors Conisbee, and cost consultants Gardiner & Theobald.
This guide is based on that work. A Decarbonisation Plan for a historic building should be underpinned by Historic England’s Whole Building Approach (WBA). This is a systematic process for devising and implementing balanced and well-integrated solutions to improve energy efficiency and climate resilience. It is implemented in a series of consecutive stages.
You should read this guide alongside:
- The Decarbonisation Plan factsheets, which provide further detail about parts of the process such as building surveys and consultant roles
- The three case studies, each with a full Decarbonisation Plan and technical report
- The Decarbonisation Plan Template
- The Decarbonisation glossary
You can also access a guide in PDF format below
What is a Decarbonisation Plan?
A Decarbonisation Plan provides a strategic roadmap to help building owners or occupiers understand how they might reduce the carbon emissions associated with the use and operation of their building. This can be achieved through a range of potential measures that aim to:
- Reduce energy demand
- Improve the efficiency of heating, lighting and other building services
- Transition away from fossil fuels to low-carbon technologies and renewable energy sources
- Make the building more resilient to future climate impacts
The result is a clear pathway of improvements that can be taken forward into future projects.
Who prepares it?
A consultant usually prepares the plan, often working with other specialists such as conservation architects, building services engineers, building surveyors, or quantity surveyors.
The consultant will start by building a full picture of the building: its history and heritage values, how it is currently used, its condition (services and fabric), its energy consumption, and its overall energy performance. They will then appraise all options available and set out a list of preferred measures to reduce emissions, considering factors including the building’s heritage significance, logistical and spatial constraints, budget and funding opportunities.
The preferred measures form the decarbonisation pathway which provides a framework to help organisations plan the next steps including identification of funding and budgets; design development, planning and listed building consents and delivery.
The 6 phases to develop a Decarbonisation Plan
The Decarbonisation Plan is developed through six phases. This process provides a clear and practical framework for collecting information, evaluating options and choosing a route forward.
The six phases align with Stages 1 and 2 of Historic England’s Whole Building Approach:
- Gather Data & Surveys
- Assess & Plan
The process also aligns with two established industry models:
- PAS 2038 – the British Standard for retrofitting non-domestic buildings
- RIBA Plan of Work – the framework used across the design and construction industry
A Decarbonisation Plan typically aligns with RIBA Stages 0–1. It sets the groundwork for progressing to RIBA Stages 2–3, where design development and planning applications take place.
The development of a Decarbonisation Plan may form part of a capital project structured around the RIBA Plan of Work, or it may be commissioned as a standalone study to help inform strategic decision- making.
Phase 1: Define
The first step of the process is to define the aims and objectives of the Decarbonisation Plan for the building owner, operator, or Board of Trustees.
The purpose of your Decarbonisation Plan will be specific to the current use, condition, heritage significance and management of your building.
- What is the intended purpose of your Decarbonisation Plan?
- How will it be used?
- What resources are available?
- Who do you need to support you in the development of the Plan?
Defining the key aims and objectives of the Decarbonisation Plan at the project outset will help your consultant team to understand the key drivers for undertaking the study. These might include:
Heritage value and accessibility
- Protection or enhancement of architectural and cultural value.
- Integration of energy efficiency measures with other improvements, e.g. extension, change of use or general refurbishment.
- Improving the usefulness, accessibility or sustainability of the building.
Building Performance
- Reductions in energy costs.
- Improvement of internal comfort and indoor environmental quality (IEQ).
- Improvement of indoor air quality (IAQ).
- Elimination of condensation, damp and mould.
- Reducing risk & mitigating overheating.
- Improvement in energy rating (e.g. asset rating, base building rating, EPC or DEC band).
- Meeting a performance standard.
Building Condition
- Protecting the building against decay or deterioration.
- Improving resistance to water penetration and resilience against flood risk.
- Improving resilience to potential future issues caused by climate change e.g. structural stability issues due to drought, overheating, increased rainfall etc.
At this stage, you should:
- Appoint a consultant team.
- Establish key points of contact for the consultants and how information will be shared.
- Develop, in collaboration with the consultant team, the principle aims and objectives of the Decarbonisation Plan for the building or site.
Phase 2: Gather
At the project outset, the consultant team will need to access a range of data and information about the building.
The consultant team will need to develop a broad understanding of different aspects of your building in order to assess its current performance. This includes:
- Heritage significance -its history and heritage values
- Physical characteristics - details about its construction and materials, and its current condition.
- How it is used - what are the hours and days of operation, occupancy numbers, any seasonal variations?
- How it is serviced - what are the heating, cooling, and ventilation systems, lighting and specialist systems?
- How it is experienced - is it too cold or draughty, does it overheat in summer?
- How it is managed - details of any maintenance schedules or plans.
- How it is funded - public funding, commercial activities, fundraising and support.
- Current challenges - are there operational pressures, financial constraints, accessibility issues, etc?
- Current opportunities - are there any potential new uses, expansions or changes?
The consultant team will require:
- Drawings of the building
- Heritage information
- Condition Surveys (fabric and services)
- Maintenance Schedules or Plans
- Environmental policies and plans
- Information on the use of the building, such as occupancy numbers, hours of operation and seasonal patterns of use
- Utility bills and/or metered energy data
At this stage, the site owner will:
- Collate and share site information with the consultant team.
The consultants will:
- Undertake site visits
- Hold briefing meetings
- Define the scope of further surveys.
Phase 3: Survey & Assess
Following the initial gathering of available information, the consultant team will undertake site surveys and prepare reports assessing the key characteristics and condition of the building and its services.
The next step of the process is to analyse and assess all the different sources of information supplied by the client and generated through the different surveys and assessments undertaken to build a picture of how the building currently performs. This includes how much energy it uses, how comfortable it feels inside (e.g. temperature, draughts, damp), and how reliant it is on mechanical systems like heating and ventilation.
Improving a building’s performance means it can stay comfortable with less energy input. For example, removing draughts can avoid the need to turn up the heating. Reducing the demand for heating, cooling, and ventilation leads to lower energy use and better overall efficiency.
To assess building performance, a range of factors should be looked at holistically, including:
- Occupancy and usage patterns - how and when is the building used?
- Condition of the building and its systems - are the walls, roof, and mechanical systems in good condition?
- Thermal performance of the external fabric - how well does the building retain heat?
- Airtightness - are there draughts or air leaks?
- How reliant is it on mechanical systems like heating and ventilation?
- Operational energy use - are there systems or processes that use particularly high levels of energy?
Collecting and analysing this information creates a baseline of the building’s current performance. This can then be compared to similar buildings (benchmarking) and used to set realistic targets for improvement. It also helps to identify specific areas where the building is performing poorly, so that opportunities for improvement can be clearly defined.
A number of methods are available to assess the annual energy use of the building. These vary in terms of inputs required, level of complexity and accuracy, and the MEP Services Consultant or Retrofit lead professional will select an appropriate method for the project in consultation with the wider professional team.
During this stage, the consultant team may need to revisit the information gathering exercise and request further site information to fill in any gaps highlighted during the assessment process. They will also:
- Collate and assess information gathered from desktop research and site surveys.
- Research and assess the history and significance of the site.
- Prepare drawings illustrating the distribution of uses.
- Assess current energy use and benchmark performance against buildings of a similar type.
Phase 4: Options Appraisal
The purpose of the Options Appraisal is to identify and appraise the range of potential improvements to the building fabric and services to reduce energy use and carbon emissions.
The potential measures are then compared against a range of criteria including carbon saving, capital cost, heritage sensitivity and logistical constraints.
At this stage, opportunities for improving the building's performance are identified and appraised in more detail. These opportunities should include upgrades to the existing building fabric and systems, such as heating and ventilation (to reduce energy use), as well as the introduction of low or zero carbon technologies (to reduce the carbon impact of the energy still being used).
Each option should be assessed against project-specific criteria to find the best fit for the building and the client's needs. The criteria used in the appraisal should consider more than just energy efficiency. Other important factors might include:
- Practical constraints (e.g. site access, disruption to operations).
- Heritage or conservation requirements.
- Upfront cost.
- Urgency due to existing defects and any maintenance and/or repair required prior to implementation of improvements to ensure their effectiveness and longevity.
- Any specific goals or limitations set by the building owner.
- Climate change resilience and other considerations.
At this stage, the consultant team will:
- Prepare a longlist of options for measures to improve energy efficiency and reduce carbon emissions. This will typically include:
- Improvements to the thermal performance of the external envelope, such as additional insulation to walls, floors and roofs, or upgrades to windows and doors.
- Improvements to the energy efficiency of building services such as lighting,
- Heating and ventilation, including addressing metering and controls.
- Introduction of low and net zero carbon technologies, including decarbonised heat sources and renewables.
- Appraise the longlist of potential improvements and outline considerations for implementation – with input and consultation from the client team.
Phase 5: Develop
Following discussion and feedback from the client team and other stakeholders, the architects and engineers will develop a list of preferred or prioritised measures.
For small buildings, the Options Appraisal (Stage 4) and Development of preferred options (Stage 5) may be carried out at the same time, particularly if the number of options available is reduced.
Following this appraisal and discussions with the client, a shortlist of preferred options should be developed. These chosen improvements will form the basis of the Decarbonisation Plan.
The final plan should outline a clear pathway for making the chosen improvements - whether as one project or in phases over time. This roadmap should support the long-term goal of achieving Net Zero Carbon for the building.
At this stage, the project team will:
- Discuss and review the findings of the Options Appraisal report.
- Agree the list of achievable measures and outline the practical considerations associated with implementation.
Phase 6: Forward Plan
The final step of the Decarbonisation Plan is to set out how the prioritised measures will be implemented over time. This is the decarbonisation pathway.
A decarbonisation pathway is a phased strategy for the progressive reduction in carbon emissions associated with the building’s operational energy use. It can be represented graphically to illustrate the relative impact of individual measures on the rate of decarbonisation over time.
The prioritisation and sequence of proposed measures will be determined by a number of project specific factors, including funding availability, heritage, and logistical constraints.
At this point, the consultant team will have enough information to:
- Develop a decarbonisation pathway illustrating how the prioritised measures will enable progressive decarbonisation of the building's energy use.
- Set out the next steps for implementation, including funding, design development, and delivery, including:
- Developing a fundraising strategy.
- Defining the brief, budget, and programme for a capital project.
- Procuring a design team for RIBA Stages 2 – 7
- Undertaking further Building Performance Evaluation to inform design development.
- Example Decarbonisation Plans (forthcoming):
- Shire Hall, Dorchester
- Lit & Phil, Newcastle
- Royal & Derngate, Northampton
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