There are four key factors to consider when understanding how a building performs and consumes energy:

• Every building has a unique historical development, physical alterations and extensions or differing programmes of maintenance. The different traditional and modern construction methods and fabrics result in fundamental differences between the performance of buildings. Traditional buildings are identified by their date, construction, and materials. Typical traditional materials used in historic buildings include lime, timber, brick and stone. They have hydroscopic properties and so are porous and permeable. Due to these properties, the materials are vapour permeable and rely on moisture being able to move through them. This is important to understand when planning changes to a building as inappropriate schemes can have a detrimental effect on a building’s fabric and significance.
• Location and orientation of a building is important when considering energy efficiency measures due to weather, which can have a significant impact on the performance of different building materials. Considering the orientation of a building, and any exposed elevations, will be important to understanding how it is required to perform or is being affected. The impact of climate change will likely mean that buildings in Essex are more susceptible to overheating.
• Building services, including the type, their efficiency and use, have an impact on the energy consumption. Building services include, heating and cooling strategies, ventilation, hot water and water systems, lighting and other electrical equipment. Understanding the performance of existing building services can help to inform the approach for enhancement. One can use Historic England’s How to Improve Energy Efficiency checklist  on ‘Understanding what you’ve got’ to inform the baseline conditions of the building’s services.
• It is important to remember the baseline that ‘Buildings don’t use energy, people do’. The way buildings are used changes the way buildings perform or are required to perform. Understanding how a building is being used, and will be used in the future, can further inform what energy efficiency measures may be most appropriate.

Limitations of Domestic Energy Performance Certificates (EPCs)

Energy Performance Certificates (EPCs) provide information on a property’s energy use, typical energy costs, and recommendations about how to reduce energy use and save money. They can helpfully identify where improvements can be made, but do not assess the building's performance as a whole. Recommendations should be considered carefully in the context of the significance and construction type of each individual historic building, and the way it is operated and used.

Further Reading on Retrofitting Traditional Buildings Historic England, Energy Performance Certificates | Historic England