Don’t believe the heat pump horror stories! That’s the message from Lee after installing a heat pump in his 200 year old home. He saved £500 on his heating and hot water bill in the first year – covering the cost of his minimal insulation improvements.

Don’t bother with an Air Source Heat Pump (ASHP)! That was the mantra from a number of heating installers last year as we were getting quotes to replace our 35 year old gas boiler. In part this was because we lived in a 200 year old property that (apparently) needed so much upgrade work for the ASHP to function effectively, it would be prohibitively expensive. Add on top of that the established narrative of ‘fabric first’, with the substantial disruption and expense it comes with, and it looked like a shiny new gas boiler was our only real immediate option.

For energy saving ideas we had been to a few Green Open Homes events put on by Marches Energy Advice (MEA) and were inspired by what other homeowners had already achieved, sometimes with quite limited resources.  We then got a lucky break in April 2023. We were kindly given some free survey work by MEA. This comprised a comprehensive energy audit of our home supported by humidity monitoring and thermal imaging. These reports proved invaluable in providing information and insights that guided our overall priorities for energy-saving.

Our bedroom night-time humidity regularly exceeded 90%. Improving air quality became our No.1 priority

The most shocking revelation from the reports was the humidity levels and the consequential health implications of the poor air quality we were exposed to during the winter. Although the monetary positive of draft-proofing our old house was evident, the negative effect, i.e. mould growth, was too. The work done by MEA showed that our bedroom night-time humidity, for example, regularly exceeded 90%! Consequently, improving air quality became our No.1 priority. 

We installed a mini Mechanical Ventilation and Heat Recovery (MVHR) system – a Vent-Axia HR100R Mini Air Handling Unit. It extracts air from the en-suite and the main bathroom, and exchanges heat with incoming air to our bedroom (only). It is plumbed into the waste water for any condensation. And it’s amazingly quiet. From an investment of less than £1,500 for this worst part of the house, the problem was solved immediately, reducing the humidity level down into the sweet spot of 40-60%.

The energy audit report identified the ‘fabric first’ initiatives as providing the biggest energy-saving potential (55%), as you’d expect. However, another big win would be replacing the extremely inefficient heating and hot water system (29%). We had already prioritised the expenditure on a new system as the existing one was on its last legs and this was the reason for looking at upgrading in the first place. So, we revisited getting that new boiler as our next priority. We had a broader view this time, however, with different perspectives gained from the Green Open Homes visits and had also become more determined to avoid the use of gas altogether, as we wanted to decarbonise.

Our fabric upgrades prior to installing the heat pump only ended up costing a few hundred pounds

We had already spent a little money on more efficient radiators for half of the house the year before. So, we knew we still had to invest in better radiators for the other half. We also wanted a hot water system operating at mains water pressure with a hot water cylinder (for later plans). At the time of costing up the various system options the government grant available was £5K for an ASHP. Its timely shift to £7.5K in October 2023 made the decision to go the ASHP route a ‘no-brainer’ from a cost perspective, when compared to an equivalent gas fired system. In order to qualify for the grant at the time we needed to improve our loft insulation from the existing 100mm to 300mm thickness. We planned to do this as our initial ‘fabric first’ contribution in any event, so we did this at a cost of a few hundred pounds.

One of the key influencing factors in choosing the ASHP was engagement with system designers that had real experience and a track record of ASHP system design and use. We were fortunate to find a designer/installer whose MD had a similar home improvement story to ours. So, despite not having undergone all the building fabric improvements prior to ASHP installation, we had a degree of confidence that what we were installing would function effectively. We hoped too that operating costs wouldn’t go up.

Don’t believe the heat pump horror stories. We actually saved close to £500 in the first year

Having had to listen to the various horror stories of poor ASHP system performance we were, naturally, still a little nervous, particularly regarding operating costs.  This wasn’t helped on our first day of full operation with a total daily electricity cost coming in at around £15. This was in the cold snap in early 2024.  Whilst a bit unnerved by that early daily cost, it proved to be an unfounded concern. It turned out we actually saved close to £500 in the first year of operation. Our total combined gas and electricity energy cost in 2023 had been £2730 and in 2024 it fell to £2250. We thought that our initial cost panic may have curtailed our use but we had been getting the benefits of lashings of hot water that we were not used to. Also, the story was repeated in 2025 with a total energy bill of £2180 (albeit a milder year, and we were no longer paying a gas standing charge of £100/yr). In big handfuls, the savings in the first couple of years had paid for the loft insulation and the little MVHR outright. And, that was without any other improvements being implemented other than purchasing a more energy efficient washing machine and making some guttering/flashing improvements.

We were particularly pleased to disconnect the gas altogether in 2024 as the only gas we were still using then was the gas hob. The cost of the daily standing charge was as much as the gas we were using, so replacing it with an electric induction hob was a convenient and simple solution.  Very easy to cook with, it also gave us the added benefit of ease of cleaning – a real winner.

We are progressing quite slowly on our home decarbonisation programme and tend to do the things that need to be done first. So the next priority is the replacement of our single-glazed windows that are near to falling out. The replacement process started March 2025 and they’re only just about to be installed nearly a year later.  This is one of the joys of living in a World Heritage Site and having to navigate a laborious planning process, even for replacement windows. The slow progress, however, does mean that we can measure the improvement benefits on an incremental basis.

In due course, we should be able to capture and share the benefits of solar panel and battery storage installation, along with significant thermal insulation improvements.

A huge thank you to MEA for their invaluable support and advice along the way.

For expert impartial retrofit advice from local charity Marches Energy Advice email tony.baker@mea.org.uk or visit www.futurereadyhomes.org.uk