Stage 1: Gather Data and Surveys

When considering interventions to a historic building for energy efficiency and/or climate resilience through mitigation or adaptation, gathering data and surveys is an essential first stage for several reasons. It helps to: 

  • Ensure thorough understanding of the building in its context  
  • Establish how the building performs  
  • Prevent unnecessary cost and carbon expenditure  
  • Minimise the risk of unintended consequences  
  • Provide objective data to inform later whole building approach stages  

This webpage outlines best practice for assimilating data and surveys as Stage 1 of the whole building approach. Links to further sources of information, standards and guidance are provided.

On this page
  1. Why is gathering information important?
  2. Define objectives and scope
  3. Gather data and surveys
  4. Produce report

Why is gathering information important?

Gathering robust information, as far as is practicable, is fundamental to understanding the building in its context and establishing an accurate energy performance baseline. Early investment in surveys and data gathering means proposals are often more suitable, simple, and cost-effective.

Collating pre-intervention data and surveys enables subsequent design and planning stages to identify interventions in response to specific opportunities and constraints through robust risk-based assessment, which ensures they:

  • Are appropriate, proportionate, effective, and cost-efficient
  • Account for the building's context, including climate change risks
  • Prioritise occupant and building health
  • Avoid harm to the significance of the building

It also allows the effect, efficacy, and cost efficiency of interventions to be predicted, measured, and monitored at various stages of the project.

The context in which proposals must be fully understood includes all aspects of the building and its setting that have potential to impact the appropriateness, effectiveness or longevity of any mitigation or adaptation intervention. They include:

  • Regulations and consents
  • Topography and site conditions
  • Location, exposure, and vulnerability
  • Use, occupancy, and management
  • Building significance, construction, condition, services, and performance

Information required to inform a whole building approach should be collected in three phases:

  • Define objectives and scope
  • Gather data and surveys
  • Produce report

All assimilated information can then be assessed, and outline proposals agreed during Stage 2: Assess and Plan and Stage 3: Design and Specify.

Define objectives and scope

The extent and nature of data gathered and surveys undertaken should always be proportionate. It is, therefore, important to establish the project objectives through a robust client brief and project scoping exercise, in terms of:

  • project requirements, aspirations and aims
  • available resources: financial, skills, materials
  • timescales and quality of work required

Next, the scope can be set, which should:

  • identify elements essential to meet the project objectives
  • consider what is feasible within the specific circumstances and available resources
  • be proportionate to the significance of the building and complexity of interventions anticipated

People may have different reasons for wanting an energy efficiency upgrade for their building. The people and organisations involved in the different stages of a project may have varied, sometimes conflicting, priorities and objectives. For some, the top priority might be the improvement of occupant health or reducing fuel poverty; for others, it might be sustaining the significance of the building. Understanding the requirements, aspirations and aims of the various stakeholders is key to devising a suitable energy efficiency strategy.

Given the right approach, the twin objectives of protecting significance and improving energy performance and climate resilience are both compatible and achievable. It may be tempting to prioritise one over the other, however, a reasonable compromise can usually be reached when decisions are well informed.

Gather data and surveys

Methods used to gather data and surveys can range from a simple 'walk through' to a highly detailed analysis that includes computer simulations. Although building owners can provide useful contextual information, suitably qualified, experienced, independent practitioners can provide a more holistic output.

It is important to review both the building and its context to understand:

  • Design, construction, materials and hygrothermal behaviour
  • Condition and efficiency of the building fabric and services
  • Local environmental factors, such as flood risks
  • Designation and significance of the building and potential harm from interventions
  • Building use and management, occupancy levels and fire safety

This should not only account for energy and carbon emissions, but also consider:

  • Climate change hazards and risks
  • Climate resilience and adaptation need
  • User comfort and indoor air quality requirements

Desk-based review

Carrying out a thorough review of available information sources, prior to visiting site, will highlight specific aspects to confirm or survey and all relevant health and safety considerations. Successful proposals are site specific and respond to the building and its context, which include:

Regulations and consent

Interventions should be designed with knowledge and understanding of the building’s regulatory and statutory context. They must be demonstrably justifiable when considering any heritage designations, building significance, planning history and restrictions, and protected species. These include:

At the outset, it is important to be aware of any heritage designations a building or site may have. If a building is listed, works may require listed building consent. If a building is scheduled, works will require scheduled monument consent. If a building is in a conservation area, permitted development rights are restricted and planning permission may be needed. Other heritage designations, such as registered parks and gardens, require the local planning authority to consider heritage issues when making decisions on planning applications.

To find out if a building is nationally designated (listed, scheduled or within a registered park and garden), search the list or check with your local planning authority.

Before planning any works to a heritage building, it is important to understand why the building is significant. Where statutory consents are needed, a statement of heritage significance will be required. This needs to be proportionate to the building's importance and must include the contribution made by its setting. It needs to be prepared by someone who understands the type of historic building, usually a suitably qualified professional. The statement of heritage significance should draw on any available published sources, including list descriptions, but it needs to be informed by a site visit to properly understand the building. Also see Historic England's advice on assessing significance of places of worship.

Mitigation or adaptation interventions, such as those intended to provide energy or carbon savings, are no different to any other works that may affect the significance of a heritage asset. The same conservation planning principles apply to weighing benefits against potential harm. Managing Significance in Decision-Taking in the Historic Environment provides further information.

Other requirements might relate to:

Previous works or development and/or the presence of restrictive covenants may affect the planning and design of energy efficiency measures. When considering works to places of worship, the impact of crypts and burials may need to be considered.

The Planning Portal, local planning departments, estate archives and records, and diocesan or cathedral archives may be able to provide relevant information.

Restrictive covenants or easements related to the site can be checked via the government's property information service.

The presence of protected species on a site or within a building may impact opportunities to improve energy efficiency and climate resilience, or the timing of works. An ecologist can undertake a desk-based preliminary scoping survey to establish the potential the site has to support any protected species and whether a preliminary site survey is needed. You can find a qualified ecologist using the Chartered Institute of Ecology and Environment Management (CIEEM) directory.  

Historic England's Building Works and Bats webpages also provide some guidance to help all involved in managing, maintaining or making changes to buildings, or using the buildings, avoid infringing the law. 

Topography and site conditions

Topography and site conditions may affect the vulnerability of the building and its occupants to different hazards, such as contaminants, structural issues, overheating or flooding. Previous reports or remediation certificates may help understand site conditions and considerations. A desk based review will quickly establish whether surveys are needed, and if so which ones. Examples include:

These may provide site level and layout information, determine the locations of water courses, drainage and utilities, as well as burials, culverts, tunnels and so on. They may also identify potential water sources for grey water systems or low or zero carbon technologies and opportunities to reduce water scarcity.

Establishing the nature, extent and location of utilities and services on site will help inform opportunities for low carbon technologies. Local utilities information and maps can be reviewed prior to the site visit.

Past structural surveys or reports should identify if the building is susceptible to subsidence or heave. They will also give a better understanding of the underlying geology to inform risk assessments. The British Geological Survey has free tools that can be reviewed, such as the BGS Geology Viewer and BGS GeoIndex.

These include asbestos and radon surveys, and contaminant risk assessments. Any building constructed before 2000 may have asbestos containing materials present, refer to the Health and Safety Executive for more information. The sites radon risk, and whether any effective protection measures are already in place may impact retrofit decisions. Consult the UK radon maps for further information. Sources of information on ground conditions and contaminants include the Coal Authority interactive map viewer. External air quality can be investigated using the DEFRA Air Information Resource and the DEFRA Smoke Control Area Map.

Location, exposure and vulnerability

Understanding the exposure and vulnerability of a building or site, including the range of climate change hazards, will aid decision making in assessment and design stages.

The location, aspect and exposure of individual elevations all influence a building's hygrothermal performance and the types of interventions that may or may not be suitable.

With traditional buildings, their location was chosen and orientation, plan form and detailing developed to be resilient to specific exposure and environmental decay factors. As extreme weather events increase in intensity and frequency, existing buildings may no longer be able to effectively manage changing climatic conditions; as a result their vulnerability will increase.

Different parts of a building are affected by different microclimates and a building's exposure to the elements is as much influenced by the proximity and position of surrounding buildings and its natural environment as it is by its own form and detailing. For example:

  • if a building is frequently subjected to driving rain or flooding, then options for wall insulation may be limited
  • where a building is exposed to sunlight for prolonged periods, the risk of summer overheating or 'reverse condensation' will dictate whether it is appropriate to install wall insulation
  • increased exposure to solar radiation will exacerbate the degradation of building materials by UV rays and thermal movement, undermining their efficacy and shortening life spans

For a whole building assessment, exposure can be informed by the Met Office climate maps and data.

Many adaptation measures for climate resilience are also effective mitigation measures. However, resilience to current and future climates has the potential to be enhanced or undermined by choices made to improve energy efficiency. This may lead to an unintended consequence of increasing the risk to occupants or building fabric to climatic hazards and their impacts.

The environment is experiencing changes in climatic conditions, such as increased exposure to direct sunlight, high humidity, intense rainfall, or wind-driven rain. This exposes buildings and landscapes to new or more extreme hazards, including increased risks of negative impacts from flooding, overheating, wind-driven rain, storm events, higher humidity, and solar radiation.

The effects of climate change are largely seen in increasingly surcharged rainwater goods and high-level stonework deteriorating on different facades. Facades previously unexposed to certain elements, such as high wind loads or wind-driven rain, may become vulnerable to decay as weather patterns change.

To ensure proposals can be designed and planned with climate change resilience in mind, it is important to identify relevant climate hazards, their potential impact and the level of risk to the building(s) and its site. Understanding the different hazards and identifying the opportunities to manage the risk of harmful impacts will support decision making. Furthermore, by understanding the tipping point (the critical threshold that when reached, will lead to the acceleration and often irreversible changes to our climate), effective planning can determine when mitigation and/or adaptation measures need to be put in place.

'Hazards' are potential negative events. The potential of external climate events occurring is not altered by the presence of a heritage asset, but the building and occupants can be impacted by their potential presence.

'Impacts' are the consequences or outcomes of these events. They are dependent on other risk determinants, such as building type, age, material, and condition.

'Risk' is the result of the interaction between climate related hazards (including the likelihood of their occurrence), vulnerability and exposure.

Use, occupancy and management

It is important to work with the building's owner/occupiers to understand their requirements and to ensure that user and building health is prioritised within any proposal. Successful high quality and low risk interventions are best achieved when a user focused approach is employed. This includes considering:

The use and tenure of a building will impact the energy performance standards that need to be considered during the planning and design stages. These include the Minimum Level of Energy Efficiency standard, and the type of certificate that will need to be reviewed, revised or produced (for example, domestic Energy Performance Certificate, commercial Energy Performance Certificate or Display Energy Certificate). The use and tenure of a building will also affect the funding streams available for energy efficiency measures. Considerations include whether a building is residential, public or non-residential, and whether it is owner-occupied, in multiple ownership, or in the private or social rental sector (local authority or housing association).

The way a building is managed, its occupancy levels and hours, building use patterns and the type of activity undertaken there, can have great bearing on appropriate interventions, energy use and the perception of thermal comfort for users. Occupant engagement is also a contributing factor. There can be considerable variations in energy use from one building to another.

Reorganising spaces may lower energy use. If possible, identify where spaces can be reordered easily to best accommodate different seasons. Factors normally considered include temperature, humidity, natural light, ventilation provision and access. For example, consider moving offices out of loft spaces that are prone to summertime overheating, or habitable accommodation out of basements where winter temperatures, low light levels, and damp may create uncomfortable conditions or unnecessary energy use.

Data gathering should include interviews with building managers and/or users to find out how they use (or plan to use) the building. It should establish if there are any special considerations, including if the building is used by vulnerable people, such as the elderly or those with additional needs. It may be useful to walk around with the owner, facilities manager, operations manager, or other interested party to identify any site constraints from an operational perspective.

Obtaining qualitative knowledge from current building users regarding how the internal environment is perceived to be performing will help inform decisions on appropriate energy efficiency measures. It is important to understand their level of understanding and engagement with energy. To ensure robust proposals, it is also important to consider that future uses, and user requirements, may vary.

Examples of occupant survey methodologies include the Likert Scale, Building Use Studies (BUS) and SOAP.

Depending on project objectives, scope and budget, user feedback can be undertaken independently or as part of a wider building performance evaluation.

Site-based review

It may be necessary to contract a competent person(s) to undertake specific elements of data gathering or surveys. Any limitations or outstanding requirements for further investigations/surveys should be highlighted in the final report.

A 'competent person' is someone with the demonstrably necessary breadth and depth of capability, knowledge, and skill to successfully comprehend and respond to the context of the property being assessed and any specific or specialist requirements thereof.

Topography and site conditions

It is crucial to check on site the validity of a desk-based review, and/or identify any further opportunities and constraints within the context of the site. For example:

  • Raised ground levels or ground that slopes towards the building make it more vulnerable to moisture from run-off and ground saturation. This may cause or exacerbate existing moisture issues or may impact decisions on the appropriateness of insulation measures
  • Areas of the natural environment that currently do not have a prescribed or viable use might be adapted to reduce overheating or flood risk and/or increase biodiversity
  • Trees, vegetation, or nearby structures may offer shelter from driving rain or high winds, but they may also affect drying capabilities
  • Other structures, assets and redundant buildings may be able to be repurposed: for example, to house mechanical and electrical equipment used to reduce the risk of fire or flood
  • The location and distribution of buildings might identify the potential for a district heating scheme
  • Car parks that are due to be resurfaced may offer the potential for ground source heat pump boreholes or collector loops to be installed. They may also provide an opportunity for installing solar panels to produce electricity to charge cars, supply the main buildings or export back to the national grid. Suitable collector types can also act as car ports to shade vehicles in the summer

Building context

It is crucial to identify and record opportunities and constraints within the context of the building's significance, construction, condition, services, and performance, including:

Building significance

It is of particular importance to identify aspects of the building's significance that may be affected by proposed works, including:

  • External features, such as building materials, windows, doors, doorcases, eaves or cornices, that contribute to the architectural and aesthetic qualities of the building
  • Interior features, such as historic plasterwork, fireplaces, cornices, doorcases, panelling and window shutters, that contribute to the historical and architectural interest of the building
  • Structural elements of historic importance, such as roof and floor structures
  • Areas of particular significance, which are more sensitive to change, and areas of lesser significance, where a greater degree of change could be accommodated
Building construction  

It is of particular importance to identify if the building is of traditional or modern construction. This will help with understanding the building's moisture and thermal properties (hygrothermal performance), suitability for intervention, and inform appropriate material choices.

Many traditional buildings will have undergone changes since their original construction, including appropriate/inappropriate repairs or alterations, and extensions of different ages and construction types. More consideration is required when designing interventions for hybrid buildings to ensure equilibrium and compatibility between the different construction types.

It is important to try and identify:

  • Age(s)
  • Construction type, structure, and materials
  • Building phases and the attachment to other dwellings or buildings
  • Building detailing or architectural features (including differences between building phases)
  • Location and type of previous alterations or energy efficiency measures already installed

Learn more: Traditional Buildings and Energy Efficiency.

A measured survey of the building should be obtained or commissioned (and it may be required as part of any planning or listed building consent applications). It should confirm the location of utility points, defects, historic or architectural features, and site constraints. It should also establish overall dimensions to enable robust calculations of heat loss areas and ventilation requirements.

Ensuring that measured surveys of buildings and services are updated after works is both good practice and helpful to inform future projects.

Building condition  

A condition survey should be undertaken to establish the location and severity of any existing defects. It should provide a schedule of repairs that need to be carried out prior to installing any mitigation or adaptation interventions.

Certain principles and competencies are required to deliver best practice when investigating moisture-related issues in traditional buildings.  

Further information on building surveying standards can be found at Building Surveying Standards.

If structural defects are identified or suspected, or excessive loading relating to use or management is observed, a structural survey may be needed.

Prioritising repair and maintenance are essential and should be regarded as the primary measure in any energy efficiency project. This not only stops the building falling into disrepair, but also means that the efficacy of interventions will not be undermined and risks to buildings and fabric reduced.

Learn more: Maintenance and Repair.

Building services 

The existing services and systems should be surveyed. The survey should establish the size, capacity, and loadings of the incoming utility services, as well as the type, age and condition of heating, cooling, hot water, ventilation, lighting and power distribution systems, plus electrical panels, switchgear, and any other equipment. This will also help to establish the delivered energy demand and measure building performance.

Depending on the scale and nature of the building, a separate ventilation assessment may be required to determine the existing provision and inform design requirements.

Learn more: Building Services Condition Surveys and Investigations.

Learn more: Low and Zero Carbon Technologies in Historic Properties.

Building performance  

Gathering robust objective data on building performance, as far as is practicable, is fundamental to identifying the accurate energy performance baseline of a building. Early investment in surveys and data gathering can save on capital costs of proposals which are often more suitable, simple, and cost-effective as a result.

Initial energy audits can be achieved by reviewing previous energy bills or smart meter data to estimate annual energy use, through an isolated energy audit or a broader scheme of building performance evaluation (BPE).

The scope and comprehensiveness of any building performance  survey should be proportionate to the significance of the building and the project’s objectives. It should consider what is feasible within the specific circumstances and available resources.

A range of non-destructive tests can be carried out to assess the thermal performance and moisture content of the building envelope, such as:

  • Air pressure testing
  • Infrared thermography
  • U-value measurement
  • Heat loss coefficient testing or calculations
  • Temperature, humidity and CO2 readings
  • Fabric moisture content and fungal testing and analysis
  • Hygrothermal assessment modelling and analysis

Produce report

The output report should succinctly set out all objective information gathered during the desk and site-based reviews, in a format suitable to inform Stage 2: Assess and Plan and Stage 3: Design and Specify. All relevant surveys, reports, drawings, photographic records, data, energy performance simulation models and files should be appended.

If a project involves the assessment of multiple similar buildings, the assessments might be combined into a single report; however, the information presented should remain building specific. For example, individual dwellings within a large historic building, block of flats or estate.