When Retrofit Goes Wrong

Retaining, using, and appropriately adapting our historic buildings can be a key part of the solution for lower carbon emissions (Historic England, 2024).

Furthermore, a whole building approach that enables an understanding of how a building performs is essential to ensure historic buildings are adapted thoughtfully and carefully and to avoid maladaptation. The Sustainable Traditional Buildings Alliance's Guidance Wheel sets out common retrofit interventions' advantages and potential risks and draws together published technical guidance from various trustworthy sources (STBA, 2020).

Below are case studies of retrofit projects that resulted in unintended consequences for the buildings and issues with the occupants' health and well-being.

Holm Farm Cottage

Holm Farm Cottage is a pair of semi-detached mid-19th-century estate cottages in Grantown-on-Spey on the Reidhaven Estate.

The original part of the building is made with rubble-walled masonry. Both parts of the building have slate roofs on sarking boards, while a later extension is constructed with cement rendering. In the early 2000s, the building underwent refurbishment, including insulating the ground floor's external walls using 100-millimetre-thick phenolic foam and replacing the windows with uPVC double glazing. However, the cottage experienced significant mould growth shortly after the refurbishment, even in the uninsulated area. The mould growth was even more severe in the new extension.

This was caused by increased moisture inside the building due to inadequate ventilation. The additional insulation led to an internal environment that could not regulate relative humidity within the building structure. The building depended on trickle vents and inadequate extractor fans in the bathroom and kitchen for ventilation. A high internal relative humidity created by occupant behaviour exacerbated the moisture problem (Historic Environment Scotland, 2013).

Preston

The work was part of the Community Energy Saving Programme (CESP), which aims to improve energy efficiency in homes in the most deprived areas of Great Britain.

In 2013, 387 small terraced houses in Fishwick built in 1900 had energy-efficiency measures installed as part of the programme. The main measures included solid wall insulation, with the installed external wall insulation expected to contribute almost half the total calculated savings.

The work was rushed due to existing installation targets and potential fines, resulting in a large portion being completed during the spring, increasing the risk of wet masonry. Many homes were in poor condition before the work, and there was a shortage of skilled labour.

A study found that the combination of poor workmanship, rushed deadlines, lack of previous maintenance and repair, and suboptimal weather conditions left residents in substandard conditions due to the retrofit work. The homes experienced severe issues with dampness, interior surface deterioration, black mould, and florid fungal growth. Plaster, furniture, and belongings were damaged in some cases, and some ceilings collapsed. Moisture retention within the external wall insulation led to humid and uncomfortable living conditions that had a detrimental impact on residents' health (Selincourt, 2018).

The Warm Wales Retrofit Programme

The Warm Wales retrofit program, funded by the Welsh Government, aimed to encourage installing energy-efficient and renewable energy measures in homes across Wales. The goal was to improve housing while reducing carbon emissions and increasing economic investment in the sector.

The program was originally designed to take a 'whole-building approach' to installing energy efficiency measures in homes. However, it took a more general approach to improving more properties with fewer measures. The program included 1,147 homes, about 40% of them pre-1919. The most common measure installed was external wall insulation, applied to 648 properties.

Following the completion of the retrofit, certain buildings experienced internal damp patches that appeared after the installation of external wall insulation. These issues were attributed to poorly fitted insulation, subpar workmanship, and tight schedules. Furthermore, there were problems with maintaining and repairing existing guttering, necessitating additional work to prevent severe future issues (WSA, 2012).

Caerau Bridgend County

In 2012, 104 houses in Caerau, Bridgend County, underwent retrofit work, which included internal and external wall insulation, at an overall cost of about £300,000.

The retrofit was carried out under 2 schemes: The Community Energy Saving Programme (CESP) – which was sponsored by the UK Government and used funding from main energy suppliers – and Arbed 1, which was both sponsored and part-funded by the Welsh Government.

The retrofit work included internal and external wall insulation. Unfortunately, the insulation work was carried out improperly, leading to issues such as damp patches on the walls, the growth of mould, and freezing temperatures inside the rooms. The damage varied from staining and algae forming due to poorly fitted guttering to the faulty sealing of service pipes and windowsills, resulting in dampness and mould. The main reasons for the failed retrofit were poor workmanship and the use of inappropriate materials (Murray, 2020).

The role of retrofitting to meet net zero targets

Retrofitting presents a significant opportunity to achieve net zero, but adopting a holistic and thoughtful approach is essential to achieve positive energy efficiency outcomes. This approach involves considering all factors that affect energy use, including the context and significance of the building itself. Using a holistic approach, energy efficiency measures can be coordinated appropriately, making them robust, sustainable, and well-integrated.

Every traditional building has the potential to become more energy-efficient, and even when special considerations are necessary, efforts can be made to ensure that retrofit measures are safe, cost-effective, and improve building performance. Heritage protection and energy efficiency are not conflicting goals; they can be harmoniously balanced (DESNZ, 2024).

References

1. Department for Energy Security and Net Zero (DESNZ) (2024). 'Adapting historic homes for energy efficiency: a review of the barriers'. (Accessed: January 2024)
2. Historic England (2024). 'Energy efficiency and retrofit in historic buildings'. (Accessed: June 2024)
3. Historic Environment Scotland (2013). 'Newtongrange Installation of roof and coom insulation and secondary glazing'. (Accessed: August 2024)
4. Murray, M. (2020). 'Bridgend council faces £1m repair bill over insulation work'. (Accessed: June 2022)
5. Selincourt, K. (2018). 'Disastrous Preston retrofit scheme remains unresolved'. (Accessed: June 2022)
6. The Sustainable Traditional Buildings Alliance (STBA) (2020). 'STBA Guidance Wheel'. (Accessed: March 2024)
7. Walse School of Architecture (WSA) (2012). 'Arbed 1 Scheme Evaluation of the Warm Wales Programme'. Cardiff University. (Accessed: August 2024)