A retrofit of one of Scotland’s famous tenements is tackling energy performance, improving health and wellbeing as well as preserving a vital legacy

TENEMENTS define urban city living in Scotland more than any other style of domestic architecture – and they were built to last, using locally sourced red, blonde and grey sandstone generally four stories high, although never taller than the width of the street. 

Officially defined as ‘two or more related but separate flats divided from each other horizontally’, tenements were the ideal housing solution for the huge influx of urban manual workers to cities during the industrial revolution and Victorian era. In fact, Glasgow’s oldest standing tenement in the Gallowgate, next to the Heilan Jessie  pub, is thought to date back to 1771.

While tenements have defining characteristics, such as sandstone facades with bay windows to the front and a shared entry ‘close’, the number of rooms and level of internal detail and decoration varied enormously across the social strata – a differential still evident today. 

The basic tenement design also provided an opportunity for many architects of the day, including Alexander ‘Greek’ Thomson, who brought classical influences to tenement buildings in more affluent emerging suburbs, such as Pollokshields. 

Fast forward 100 or so years and tenements remain a much-loved and substantial sector of the Scottish property market. But there is now a new dilemma: how to address climate change and improve the energy performance of traditional housing stock without compromising Scotland’s architectural heritage – a challenge exacerbated for tenements given the constraints of housing multiple family units under one roof.

Now a ground-breaking retrofit pilot project by John Gilbert Architects on a 120-year-old Glasgow tenement, has just been completed and it offers a genuinely innovative solution to the challenges of both climate change and fuel economy

Located close to Queen’s Park on the south side of the city, 107 Niddrie Road comprises eight small flats over four storeys, which were empty and in a perilous state. 

Following purchase by Southside Housing Association and a first-of-its-kind retrofit supported by the Scottish Government, Glasgow City Council, CCG (Scotland), and the housing association itself, these eight new homes, designed using the EnerPHit standard – the retrofit version of the more familiar Passivhaus standard used on new buildings – benefit from an astonishing 80-90 per cent saving on heating costs, a level of energy efficiency that mitigates fuel poverty while drastically reducing carbon emissions. 

“This is the first sandstone tenement in Scotland to attempt this and the resulting high-quality homes provide a range of pointers towards a more robust and sustainable future for tenements, which are such an important part of Glasgow’s and Scotland’s built heritage,” says Chris Morgan, director of John Gilbert Architects. 

“These eight homes are actually more energy efficient than a new-build equivalent, and as well as energy and carbon savings, this project has addressed several health and wellbeing issues head on, while also considering aspects of heritage and adaptation to climate change.” 

The Herald:

Although made possible by the flats being empty, the Niddrie Road tenement block was a particularly difficult choice owing to its large north-facing front windows, which only ever lose heat, while the south-facing rear windows were small and largely shaded by adjacent buildings and trees. 

“This made the energy balance more expensive,” says Morgan. “Many similar projects will be easier.”
Briefly, the project involved high levels of insulation to roof, floors and walls, with external insulation installed on the outside of the walls at the rear, but inside the walls facing the street.

Windows were replaced with triple-glazed alternatives and a lime plaster was used throughout to drastically improve the levels of airtightness. Mechanical ventilation with heat recovery (MVHR) was used to recycle warmth from outgoing air, and wastewater heat was also recovered, the latter using warmth from water going down the shower or bath drain to pre-heat the cold water about to be used – reducing costs and carbon emissions of hot water by 40 per cent. 

The street-facing stonework was restored and improvements and repairs made to the roof area. Heritage issues were uppermost in the design development, with the street-facing facade re-pointed in a traditional lime mortar, while damaged stone was replaced with matching natural stone and other repairs made to restore the building close to its original condition. 

Gas boilers were replaced in four of the flats, while the other four have been fitted with air source heat pumps – and the flats will all be monitored to assess their performance over the next year or two. Funding for the monitoring came from the Scottish Funding Council, which has also allowed for extensive dissemination of the project and the lessons that will be learned. 

Work started in November 2019 and CCG (Scotland) was at the sharp end of the project, working to rigorous new standards to achieve the general level of enhancement required for the EnerPHit standard. “Our biggest challenge was to get the building to the level we did at the height of the COVID pandemic,” comments Chris Murray, CCG’s development and marketing manager. 

“The pandemic also impacted on the supply of materials – and as this was a site for specialist workers only, often working in very tight spaces, there were no apprentices on the project.”
Health and wellbeing were another key project consideration and after lower fuel costs, the next major benefit for home occupiers is being able to live in comfort. 

“In winter it will not be expensive to keep the flats warm and in summer, they can be kept cool,” says Morgan, who worked with project architect Drew Carr. 

“These flats have controlled humidity and no mould or condensation thanks to high performance MVHR – and a marked reduction in the low-level toxicity built into many conventional building products and finishes, such as paints. 

“Here we have used natural wood fibre insulation and lime plaster in lieu of plastic membranes – but most important, we avoided the widespread use of chemicals which were initially proposed to treat the timbers in the building,” he adds. 

Happy, healthier, and considerably wealthier thanks to the new low fuel costs, to say the tenants of these eight flats are delighted is the understatement of the year.

When compared to demolition and new build, retrofitting buildings saves huge quantities of embodied energy and carbon. 

And, according to Morgan, all retrofits can offer this benefit, but unlike Niddrie Road, few can say the resulting homes will be more energy efficient than the 
new build properties that could have 
been built. 

This ground-breaking project has achieved the best of both worlds: much reduced embodied carbon and much reduced operational energy into the future. “Safeguarding Scotland’s built heritage is a critical part of a sustainable future, if for no other reason than we couldn’t possibly afford – in carbon terms – to demolish and re-build all the country’s homes,” concludes Morgan. 

“A better option is to protect the older homes and buildings people know and love, while ensuring they consume a tiny fraction of the fuel they currently do.” 

The elephant in the room, of course, is how will retrofit be paid for, and by whom? 

Meanwhile, the Niddrie Road project shows what can be achieved, making it a well-deserved winner of the new Green Housing Category in the Herald Property Awards for Scotland 2023. 


  • Tenement flat owners can find impartial information and advice on repairs, maintenance, retrofit technologies and more from www.underoneroof.scot