There’s a prevailing belief that air-source heat pumps aren’t an option for older tenements - so many challenges have to be faced before one can even be installed, particularly in the pre-1919 stock which is amongst Scotland’s draughtiest.

But such issues did not stop Dr Jane May Morrison, who has a hybrid air-source heat pump installed on the wall outside her ground floor tenement in leafy Shawlands, Glasgow. Inside the building, just along from where her British Blue cat sleeps, is the gas boiler element that provides the fossil fuel element of this hybrid.

“I did it because I really wanted to decarbonise,” she said, “and as a first-time owner, this was my first chance to do it. My PhD is in climate and low carbon living and ecotowns, so I’ve studied the research and what has been coming out recently indicated that it might be possible to do this.”

Dr Morrison, who now works as a renewables specialist with Ripple Energy, was an energy advisor at Home Energy Scotland when she first hatched the plan. “I wanted to test it out. Working where I was, I thought it wouldn’t be right to be able to say do as I say, not do as I do. l. If I’m going to spend my day recommending to people that these are a very clever, very futureproof form of heating, then I should be willing to get one on my own home as well.”

The 36-year-old wanted to have personal experience of heat pump technology so she could “tell other people about it in detail”.

“I have climate motivations as well,” she said. “I want to decarbonise. I want to cut my carbon footprint, as many people do nowadays. And I also thought I could run it more efficiently - with some more insulation we could get the energy bills down over a period of time.”

One of the myths she was keen to dispel is the idea that heat pumps are only for new homes. “I try to base my evidence on the research evidence - and the newest research indicates that when you compare people in period properties and those in newer properties, when they both get heat pumps, the satisfaction rating is about the same. That’s what the research coming out in the last couple of years is showing. This is a field in which lots of things are changing rapidly.”

The Herald: Dr Jane May Morrison pictured at home in the Southside of Glasgow. Dr Morrison has had a heat pump fitted at her ground floor tenement flat... Photograph by Colin Mearns.16th May 204.For The Herald, see interview by Vicky Allan.

In Scotland, there are around 895,000 properties legally defined as tenements (buildings comprising two or more flats) though the type of pre-1919 tenement that Dr Morrison lives in is often referred to as a traditional tenement. Glasgow alone has 70,000 of these, and across Scotland there are 182,000.

Older tenement homes, according to Scottish Government research, emit on average 5.6 tonnes of carbon a year, compared to 3.6 tonnes from those built after 1982. Since two-thirds of pre-1919 flats have disrepair to critical elements and 5% require extensive repairs, there is also often much work to be done even before starting a retrofit.

Amongst the biggest challenges are that they are poorly insulated, and their solid stone walls don’t lend themselves to external insulation. But there are also the challenges attached to their mixed tenure, and tenement planning and law, which does not enable block changes.

None of this, however, stopped first-time homeowners, Dr Morrison and her husband, Dave. One of the first things she did was get a home assessment for her flat, hiring in Chris Carus of Loco Home Retrofit, who assessed “where the cold spots were and which bits needed insulating the most and what kind of insulation would be best”.

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Dr Morrison had both interior wall and underfloor insulation fitted. She chose a hybrid unit, because she was, she observed, “advised it was best for a flat which is a relatively untested retrofitting. But I was all set to go 100% heat pump".

Her Daikin Altherma Hybrid system runs off both gas and electricity and can be set to choose the cheapest available fuel source at any given time.  But she has it set to run in a “low carbon way” which means a quarter of her energy is from gas and three-quarters from electricity.

Currently she is paying £150 a month for her Octopus energy bills. “Like everyone in the country I would like to see energy prices come down. But £150 a month isn’t bad compared to some of the things I’ve heard people paying.”

This, for her, is a mission. “Because it’s my career area,” she said. “I wanted to prove it was possible. I wanted to have that experience of it. I wanted to be able to demonstrate to people that I’ve done it. It does work. Proof of concept.”

But even this enthusiastic early adopter does not believe individual air-source heat pumps, and retrofits, are the answer to the problem of insulating and decarbonising Scotland’s tenement stock.

“Because," she said, "there are so many tenements in Glasgow, we should be looking at how to do it building-by-building, not flat-by-flat. It’s great that I’ve done this, but actually now it's much more difficult for my neighbour to get one because the rule is one per building the rule is one per building unless planning permission is granted. How are we going to decarbonise with regulations like that?

The Herald: Dr Jane May Morrison pictured with her heat pump at her ground floor tenement flat in the Southside of Glasgow... Photograph by Colin Mearns.16th May 204.For The Herald, see interview by Vicky Allan.

“Really it would be more sensible if we could have one-per-floor or full-building retrofits and if insulation could be coordinated for whole buildings. Current regulations haven’t caught up yet. They are designed as if everyone lives in a little detached house.”

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Dr Morrison is not alone in attempting to retrofit a tenement. Others have done it.  Chris Carus, executive officer of the Glasgow cooperative Loco Home Retrofit, has done independent assessments of numerous older homes that have achieved successful retrofits.  

He cited a homeowner who had a heat pump installed inside a second-floor tenement flat. “It was very expensive because there was no space for the heat pump outside, so they were very committed and they spent a large proportion of the value of the flat on the heating system. Economically, it doesn’t make any sense unless you place a value on your environmental impact.

“We used equipment that was designed for use on the continent where the heat pump market is much more mature - in Norway, Sweden, Germany -  where heat pumps are going into flats and houses from new build and generally those properties are bigger than Scottish properties.”

Whilst few individuals have taken it into their own hands to DIY retrofit their homes, there have been larger full-block retrofits that have tested the possibilities of insulating and decarbonising whole buildings. One of these is the 107 Niddrie Road block which was converted by John Gilbert Architects to “near-Passivhaus reduced energy demand” chiefly through ultra-high insulation measures, which included triple glazing, internal wall insulation and external wall insulation.

The learnings from that construction are listed in the report Niddrie Road, Glasgow: Tenement Retrofit Evaluation. Among the issues it said needed tackling were “how to address the use of ASHPs in tenements so that they can be developed for all floors".

The fact that traditional tenements tend to have such high emissions makes it all the more important that they are insulated, draught-proofed and decarbonised.  Numerous ideas exist for how they may be heated: from district heating plans that draw from waste heat or the river Clyde to networked ground source heating like that installed by the Cornish company, Kensa, which connects up blocks, terraces and tenements to heat drawn from boreholes deep into the ground.

But the landscape for homeowners and tenement dwellers remains confusing, even if Dr Morrison has worked out her own pioneering ground floor solution. More clarity is needed.