This browser is not fully supported by Historic England. Please update your browser to the latest version so that you get the best from our website.

Energy Efficiency

Understanding the energy performance of historic buildings and the effects of measures to increase energy efficiency.

Improving energy and carbon performance of historic buildings helps them remain viable and useful, now in the future.

There are numerous incentives for carrying out improvements:

  • mitigating climate change
  • maintaining energy security
  • reducing energy costs and tackling fuel poverty
  • increasing comfort
  • complying with legislation

Unfortunately, unsuitable improvements may not deliver the savings predicted, and can harm the building and the health and well-being of its occupants. This aim of this research topic is to contribute to an evidence base that will enable better-informed decisions to be made about improving the energy and carbon performance of the historic built environment.

Co-heating tests and in situ U-value measurements being carried out to assess  the thermal performance of the building envelope of a Victorian terrace house
Co-heating tests and in situ U-value measurements being carried out to assess the thermal performance of the building envelope of a Victorian terrace house © Iain McCaig / Historic England

Thermal performance of traditional buildings

Research into the thermal performance of brick walls.

Two studies have been carried out that focus on the thermal performance of solid brick walls. The aim the project was to quantify thermal transmission in terms of U-values by measurement in situ and complementary laboratory investigations.

Partners: Glasgow Caledonian University

Programme and progress:  Project complete – executive summary and research report published

Read the research report: Thermal performance of traditional brick walls

113 New Bolsover: Whole house thermal performance assessment.

The aim of this project is to understand better the thermal performance of the roof, walls, floors and windows of a traditional dwelling, and the effectiveness of fabric improvements in reducing energy use and carbon emissions. The thermal performance of a two storey, end of terrace house in New Bolsover, Derbyshire was assessed before and after improvements carried out in 2011 using measured U-values and a co-heating test, and the results compared with calculated values. The effectiveness of the measures was evaluated using the SAP model. In addition, the cost efficiency of improvements was assessed.  Measurements of elemental U-values will be repeated in 2017.

Participants: Historic England's Building Conservation and Research Team; Glasgow Caledonian University; Bolsover District Council

Programme and progress: The first phase of the project is complete; U-values have been re-measured in 2017 - report forthcoming.

Read the research report:
A Retrofit of a Victorian terrace house in New Bolsover: A whole house thermal performance assessment

New Bolsover retrofit of victorian house terraced house: A whole house thermal performance - research report front cover

External wall insulation in traditional buildings: Case studies of three large-scale projects in the North of England.

Research was commissioned into three large-scale external wall insulation projects in the North of England. This focussed on a range of issues including methods of funding, pre-installation assessments, selection of materials and systems, design, specification, procurement and implementation, and highlighted factors affecting the quality of work.  In addition, the heritage impact of the work was assessed, and the perceptions of stakeholders, including building occupants, were reviewed.

Participants: Historic England’s Building Conservation Research Team; NDM Heath Ltd

Programme and Progress: Project complete.

Read the research report

Research into the thermal performance of traditional windows.

Historic England commissioned research to investigate the thermal performance of traditional timber sash windows and metal windows. Thermal transmission in terms of u-values was measured, and heat losses through air infiltratration draughts and thermal bridging were assessed. The work presented in the research reports quantifies the effectiveness of relatively simple measures to improve the thermal performance of windows by draught-proofing, and using blinds, curtains, shutters and secondary glazing.

Partners: Historic Scotland (now Historic Environment Scotland); Glasgow Caledonian University;

Programme and progress: Project complete – exective summary and research reports published

Read the research reports:
Research into the thermal performance of traditional windows: Timber sash windows

Research into the thermal performance of traditional windows: Timber sash windows (Executive summary)

Improving the thermal performance of traditional metal-framed windows

Improving the thermal performance of traditional metal framed windows - research report front cover

The Engine House, Swindon: Thermal performance of energy efficiency improvements to timber windows.

Tests have been carried out at Historic England’s headquarters in Swindon to compare three proprietary retrofit systems for improving the thermal performance of traditional timber windows. To assess their performance, U-values of glazing were measured in situ before and after the systems were installed. The results showed that all three systems reduced heat loss by more than 50%. The impact of each system on heritage values, and the operation and maintenance of the windows was also considered.

Participants: Historic England's Building Conservation and Research Team

Programme and progress: Project complete, report published.

Read the research report

Other related reports reports:

The SPAB Research U-Value Report

The Engine House, Swindon, Thermal performance of energy efficiency improvements to timber windows - research report front cover

Moisture accumulation in building fabric due to energy efficiency measures

A programme of complimentary laboratory and site-based projects is underway to understand better the risks of condensation and moisture accumulation in building fabric due to retrofitted energy efficiency measures.


113 New Bolsover: Hygrothermal behaviour of internally insulated brick walls.

The aim of this project is to monitor and compare the long-term effects of internal wall insulation (IWI) on the hygrothermal (moisture and heat) behaviour of solid brick walls in a Victorian end-of-terrace house in New Bolsover, Derbyshire. Two IWI systems have been installed, one ‘vapour diffusion closed ‘ (PIR), the other ‘vapour diffusion open’ (wood fibre). Temperature and moisture sensors have been installed at the interface between the insulation and the wall in XX locations . These are continuously monitored, along with the temperature and humidity of the intereior of the house.

Participants: Historic England's Building Conservation and Research Team; Glasgow Caledonian University; Ridout Associates; Bolsover District Council.

Programme and progress: Research report on 5 years of monitoring forthcoming in 2017. Walls to be monitored for a further 3 years.


Shrewsbury Flaxmill Maltings: Hygrothermal behaviour of internally insulated brick walls.

This project is investigating the ways that both insulated and uninsulated solid brick walls respond to internal and external environmental loads. Two systems of internal wall insulation have been installed, as described above, in part of an 18th industrial building which is being heated and humidified to replicate occupation. Temperature and moisture sensors have been installed at the interface between the insulation and the walls. In addition, moisture sensors have been placed at intervals within the thickness of the wall. These are continuously monitored, along with the internal climate. Outside, a weather station monitors meteorological conditions, including solar radiation, and vertical rain gauges on the facades record wind driven rain.

Participants: Historic England's Building Conservation and Research Team; Glasgow Caledonian University; Ridout Associates;

Programme and progress: Research report on 2 years of monitoring forthcoming in 2017. Walls to be monitored for a further 3 years.


Laboratory-based investigation: Hygrothermal behaviour of internally insulated brick walls.

The aim of this project is to monitor and compare the effects of different IWI systems on the hygrothermal behaviour of sample brick walls when subjected to ‘internal’ and ‘external’ environmental loads in a climate chamber. The data obtained will be used to assess the risk of moisture accumulation, and cross-validate data gathered in site-based monitoring. The project will also measure the effects of moisture on the thermal resistance of sample walls.

Participants: Historic England's Building Conservation and Research Team; Glasgow Caledonian University;

Programme and progress: Research report on first phase of monitoring forthcoming in 2017.


Hygrothermal behaviour of roof spaces.

This project is investigating the behaviour of heat, moisture and air in a range of traditional pitched slate and tile roofs under the influence of internal and external environmental loads. Up to five roofs, with and without underlay and with varying amounts of insulation either at ceiling level will be continuously monitored. Internal parameters include temperature and relative humidity above and below insulation and below ceiling, air velocity at high and low level, and surface temperatures of roof coverings and underlay. Timber moisture content is also being assessed. Externally, weather stations record meteorological data. The aim is to understand better the factors affecting the risk of condensation and moisture accumulation, and to evaluate the effectiveness of ventilation in managing the condensation risk.

Participants: Ridout Associates; Arboreal Architecture; building owners

Programme and progress: Ongoing – 2 years of monitoring complete in two roofs. Interim research report forthcoming in 2017.


Hygrothermal behaviour of suspended timber ground floors.

This project is investigating the behaviour of heat, moisture and air in sub-floor voids to assess the risk of moisture accumulation when insulation is provided at floor level. The effectiveness of ventilation in maintaining timber moisture contents at safe levels is also being appraised. Internal and external environmental parameters are being continuously monitored.

Participants: Historic England's Building Conservation and Research Team; Ridout Associates; building owners.

Programme and progress: Ongoing – 1 year of monitoring complete. Interim research report forthcoming in 2017.


SPAB Building Performance Survey - Phase 2.

The Society for the Protection of Ancient Buildings (SPAB) Building Performance Survey is assessing the effects of energy efficiency refurbishment in traditionally constructed dwellings on various aspects of building performance. This first stage of the survey began in 2011. It included measurements of fabric heat loss, air leakage, indoor air quality, room comfort and wall moisture behaviour before and after refurbishment in seven houses. Since 2014 the second stage of the survey has focussed on monitoring the behaviour of heat and moisture in external walls at three of the properties. 

Participants: Society for the Protection of Ancient Buildings; ArchiMetrics; building owners.

Programme and progress:  Final year of monitoring in progress. Interim research reports published 2014 and 2015. Final research report forthcoming - 2017.

Useful contact: Society for the Protection of Ancient Buildings

Read more about this project:

SPAB Energy Efficiency Research

Numerical modelling of hygrothermal behaviour of building fabric

A programme of research to investigate factors affecting the accuracy of hygrothermal modelling, and its usefulness in assessing risks of moisture accumulation in walls due to retrofitted insulation.


Shrewsbury Flaxmill Maltings: Hygrothermal Modelling.

Heat and moisture transport through brick walls at Shrewsbury Flaxmill Matlings were modelled using WUFI Pro 5 software. The aim of the study was to simulate the hygrothermal behaviour of the original construction and predict the impact of adding different types of internal wall insulation. Thirty-year simulations were carried out using climate data from a nearby location and measured material properties of a sample brick from the Flax Mill. Simulations were also run using material properties from the WUFI database. Different insulation systems were modelled including mineral wool, PIR and wood fibre. The results indicated that predictions are subject to high levels of uncertainty if measured material properties are not available, and where boundary conditions such as absorption of driving rain are unknown. The hygothermal behaviour of walls at the Flax Mill is currently being monitored. These measurements will be used to validate predictions and ‘calibrate’ the model.

Participants: Glasgow Caledonian University

Programme and progress: Complete - report published.

Read the research report:
Hygrothermal modelling of Shrewsbury Flaxmill Maltings

Shrewsbury Flaxmill Maltings hygrothermal modelling - research report front cover

Sensitivity analysis of numerical modelling using WUFI Pro 5.

Software applications (such as WUFI ®) that simulate hygrothermal behaviour of buildings and components are often used to assess the risk of moisture problems, for example where additional insulation is proposed. However, doubts about construction, material properties, internal environment, occupant behaviour and external climate lead to uncertainty in the output of simulations. The aim of this project is to investigate how uncertainty can be apportioned to various input data and identify the input fields that have the most significant impact on the accuracy of results.

Participants: Glasgow Caledonian University

Programme and progress: Complete. Research report forthcoming - 2017.


113 New Bolsover: Hygrothermal Modelling.

This builds on the two previous projects, described above, and has similar objectives: to validate the model and understand better the factors affecting the accuracy of predictions. The hygrothermal behaviour of internally insulated walls at 113 New Bolsover is being simulated using WUFI Pro software. The results will be compared with data measured on site over the past five years.

Participants: Glasgow Caledonian University

Programme and progress: Commmenced. Research report forthcoming - 2017.

'Whole building' approach to energy and carbon savings in historic buildings

Analysis of energy saving measures in four solid-walled houses in Reading.

An in-depth ‘whole building’ analysis of energy use has been carried out in four traditionally built houses in Reading, Berks. The results have been used to devise bespoke packages of measures to reduce energy use and carbon emissions. These were then assessed in terms of their effectiveness and cost-efficiency. A particular aim of the project has been to understand better the costs and benefits of solid wall insulation in relation to other energy and carbon saving measures. The project demonstrates the benefits of a ‘whole building’ approach, and shows how the economics of specific energy and carbon-saving measures vary from one household to another.

Participants: Parity Projects; Reading Borough Council

Programme and progress: Complete. Research report forthcoming - 2017.  


The sustainable use of energy in traditional dwellings: Legislation, policy and decision making.

Local authorities are responsible for implementing a diverse range of legislation, policies and guidance relating to sustainable development, fuel poverty, housing standards and carbon reduction. These all have impacts on the historic environment. But unless there is adequate inter-departmental understanding and coordination of the many overlapping (and sometimes conflicting) requirements, there is a risk that one agenda will be undermined by another. The consequences of this include harm to heritage assets and failure to meet legislative and policy objectives in full.

The aims of this project are: a) to review current legislation, policy and guidance, and understand better the points of convergence and conflict; b) consider ways that local authorities can increase understanding between departments and stakeholders, and develop more integrated and better informed approaches to policy and decision making.

Participants: Centre for Sustainable Energy, Bristol

Programme and progress: Complete.

Read the research report

The SPAB building performance survey

The SPAB's Building Performance Survey, is a research project supported by English Heritage that is assessing the performance of a number of traditional buildings both before and after refurbishment designed to improve energy efficiency. Early phases of the project focussed on quantifying the thermal performance of a range of traditional wall constructions, including stone, brick and cob, by measuring their thermal transmission in situ. Measurements were carried out before and after refurbishment, and the effects of the energy efficiency measures on comfort and indoor air quality were also assessed. The current phase of the project is looking into the long-term effects of adding insulation on the behaviour of interstitial moisture in walls.

Partners: The Society for the Protection of Ancient Buildings (SPAB); ArchiMetrics; Caroline Rye; Diane Hubbard; building owners

To read more about this project and the research outputs:
The SPAB Research Report 1: U-value report

The SPAB Research Report 2: The SPAB building performance survey

The SPAB Research Report 3: The SPAB hygrothermal modelling

SPAB energy efficiency research

Contact for all above projects: Conservation@HistoricEngland.org.uk

Was this page helpful?

Also of interest...