The Importance of Retrofitting Historic Homes: Learning From a Tenement Experiment in Glasgow

The Importance of Retrofitting Historic Homes: Learning From a Tenement Experiment in Glasgow

Rob Richardson, with support from the UK Collaborative Centre for Housing Evidence (CaCHE)

Reaching net zero over the coming years will depend on retrofitting existing buildings, as 80% of the housing stock the UK will have in 2045 already exists. The UK’s ageing housing stock will not be straightforward to retrofit, however; homes in the UK on average lose heat up to three times as fast as those in Germany, for instance.  

Historic buildings bring a unique dimension to this retrofit challenge. The distinctive tenement flats which line Glasgow’s residential streets are a fundamental component of its identity. The term tenement most commonly refers to the pre-1919 sandstone three or four storey apartment buildings, set around a communal stairwell or ‘close’. Glasgow has approximately 77,000 such pre-1919 tenement flats, which account for a quarter of the city’s housing stock. 

Tenements are a versatile built form, and while in the industrial inner-city families once lived in one-room ‘single-ends’, larger tenements are still sought-after among professionals and families, particularly in more affluent parts of the West End and Southside of Glasgow. Tenement blocks are therefore often mixed tenure, have a diverse mix of occupants, and can accommodate retail and hospitality uses at ground level, creating high-density mixed-use neighbourhoods across the city.

The UK Collaborative Centre for Housing Evidence (CaCHE) recently held a conference on retrofit solutions for older housing, at which it launched the report of a comprehensive evaluation of an exemplar retrofit scheme at Niddrie Road. Funded by Glasgow City Council, Scottish Funding Council, Southside Housing Association, and the Scottish Government, the project aimed to deliver an EnerPHit level retrofit (PassivHaus for existing buildings) to a ‘typical’ four storey tenement block.

Despite the age of the building, the poor condition it was in, and various other logistical challenges, the retrofit was successful. 12 months on, the dwellings perform below targeted levels of energy consumption, provide a comfortable and healthy environment, and with high degrees of occupant satisfaction – particularly given the resulting drop in energy bills.

Scaling Up Retrofitting: Challenges and Opportunities

Retrofitting homes to this standard, however, is costly. The EnerPHit retrofit element for each one-bedroom unit at Niddrie Road cost approximately £30,000-40,000 – not including the necessary initial refurbishment of the properties. Governments across the UK have increasingly been looking at how to finance retrofit and encourage its uptake. The Scottish Government’s Green Heat Finance Taskforce is due to report imminently on innovative financial solutions for building owners in Scotland, while shortly before COP26, Glasgow City Council launched a £30bn ‘Greenprint for Investment’ portfolio which includes a 10 year £10bn city-wide housing retrofit programme. Across the UK’s largest cities, the Cities Commission for Climate Investment (3CI) is similarly aiming to mobilise investment in local level low and net zero carbon projects.

Beyond finance, several “thorny challenges” will require the careful coordination of different policy actors and objectives if the UK’s ageing homes are to be retrofitted at the scale and pace needed. In the case of the Niddrie Road project, Glasgow City’s planning policy for tenements restricted the options for external changes to the building, including preventing the installation of photo-voltaic roof panels and attaching air-source heat pumps to the external walls. This required compromises such as locating heat pumps in the back yard and only at ground level, meaning that in practice, the top two floors could not have them. This demonstrates the intricacies involved in navigating novel net zero projects through policy requirements which span tiers of government.

The users of buildings themselves also have an important role in shaping the success of any retrofit to the physical fabric, because ‘buildings don’t use energy: people do’. While most feedback from residents at Niddrie Road has been positive, the users reported being unsure how to operate the systems, which could compromise the comfort of others and the overall effectiveness if heating was left on unnecessarily, for instance. The housing association which owns and manages the communal spaces therefore needs to play an active role in supporting tenants to manage the system, as well as effectively maintaining it and troubleshooting when problems arise.

Understanding people’s behaviour can help to expand home retrofit schemes. Work by the Behavioural Insights Team finds that, in addition to high cost, homeowners are put off retrofitting their properties by the perceived hassle of arranging installation, and a lack of trusted installers. Replicating the ‘one stop shop’ model that exists in Ireland (through the Sustainable Energy Authority of Ireland) could address this, according to Behavioural Insights Team, as could normalising retrofit by making it more visible. The International Public Policy Observatory (IPPO) has recently recommended that Home Upgrade Agencies be established to provide a mixture of subsidies, loans and practical support to households, using a data-driven approach to tailor information to households. Intermediary enterprises are already beginning to fill this space.

Beyond the environmental benefits of retrofitting historic buildings

Beyond the environmental gains, research suggests that there are significant economic benefits to investing in retrofitting historic buildings. The UK’s low carbon and renewable energy economy was worth £46.7bn in 2018 and employed 228,400 people, which is forecast to rise to 700,000 direct jobs by 2030. Addressing a heritage and carbon skills gap – according to a report by the National Trust, Peabody Historic England, the Crown Estate, and Grosvenor- could also support £35bn of economic output annually. 

At a more local scale, this could create opportunities to develop skilled local supply chains, particularly in rural areas. Research by the Centre for Local Economic Strategies in the south of Scotland, for example, has found that retrofit programmes could generate £340m in Gross Value Added (GVA) and sustain 6,690 jobs, just within Dumfries and Galloway and the Scottish Borders. 

Retrofitting homes across the UK can therefore address several cross-cutting policy problems simultaneously. Contributing to local economic development can help support a just transition, while significantly improving poor overall housing conditions. This could also have major health and wellbeing benefits for occupiers across the UK by reducing current high levels of fuel poverty; which is estimated at 13% of households in England, 25% in Scotland, 14% in Wales, and 24% in Northern Ireland1.

Policy responses must take care to ensure that these benefits are accessible across housing tenures, however. Different policy responses to those targeting owner-occupiers will be required in the private rental sector, for instance, where housing interests are split between landlords, agents and tenants. The presence of a housing association meanwhile, as was the case at Niddrie Road, provides a stakeholder with a financial and social long-term interest in any retrofit investment. The Niddrie Road project was indeed only possible because a housing association was encouraged by Glasgow City Council to purchase units to diversify the local mix of tenures, and as a result, all the units being empty simultaneously provided a rare opportunity to experiment with the building in its entirety.

Retrofitting older housing demonstrates the unique ways in which policy problems intersect at the site of the home. Glasgow’s tenements are highly symbolic in this regard, as an instantly recognisable part of the city’s urban fabric and its social heritage. They will need to be a leading part of the city’s net zero future, and lessons from this work are important to understand if we are to tackle the problem of the UK’s ageing housing stock across the country.

  1.  Comparisons between the nations cannot be easily made due to differences in recording methodology

For more work from IPPO on Net Zero and housing see: The Home Retrofit Challenge: How is it Financed? and The Case for Home Upgrade Agencies: Mobilising Data for Net Zero.