Heading into our third winter with a heat-pump, how's it going?
In 2021, in that briefly optimistic period post-lockdown and pre-Ukraine, we took the plunge and installed a heat-pump in our 1930's bungalow. In our previous blog we spoke about the installation process, the complicated plumbing, the set-up process and the impact on our house. Two years on, here's an update on our experience so far.
As we covered in our first blog, we installed a 14kW Ecodan heatpump from Mitsubishi. The work was all organised by the excellent Warmworks as part of the Electrification of Heat Demonstration Project funded by the Department formerly known as BEIS.
Is it warm enough?
Before we get into this, I should clarify that the two of us have different perceptions of heat. I like it a degree or so warmer than Andy (I'm 20C he's 19C) and will spare the blog from marital tension: this is my experience!
Over all, the system has coped well with two Scottish winters, and we've never been cold. We have mixed insulation performance throughout the house as it's been extended over the years, and this is definitely noticeable. We have one room that is chiller than we'd like, it has two exterior walls (cavity insulated), under floor insulation and a double glazed bay window. When we investigated with a heat sensor we discovered that the bay window has a double cavity (who knew?). Only one cavity was reached by the wall insulation, and so we have a cold spot as the wind whistles through the open cavity taking our heat with it.
The newer part of the house (upstairs loft conversion and rear extension) is super cosy, with upstairs radiators only needing to be on trickle heat. Downstairs, my desk is in the chilly room mentioned above, and on cold windy days I do use brief blasts from a supplementary fan heater to keep me topped up - but this is no different from when we had a gas boiler. We also have a log burner (what can I say - girl's a forester), which we use to accompanying a dram or two on long, dark, Scottish evenings. We spend about £150 a year on local kiln-dried logs.
As for hot water, we've had house parties with multiple guests, and the tank has coped fine with 4/5 people taking a shower over the course of an hour and no-one getting an unwanted ice-bath.
What impact on energy use?
In spite of being part of a trial to monitor energy use, access to the data from our smart meter was not as easy as it should have been. However, our supplier (Octopus energy) has now started sharing all our half-hourly data, so now I can be as nerdy as I want. The results are pretty striking: our total energy use has dropped by about 2/3rds.
As the graph shows, this big reduction has been pretty consistent throughout the year and across years with different weather patterns. Lockdown impacts have been limited as I work from home and the rest of the family are back and forth a lot, so there's usually someone around. For the times when we are away, we're still learning how best to use holiday modes: if it's only for a couple of days, the loss of heat from the thermal mass seems to take a whack of energy to get back, so we're experimenting with finding the sweet spot (seems to be when it's over 48 hrs).
Cost
You would think that with such an enormous reduction in energy use, that our bills would also be tiny. Sadly not, due to a) our roof having a poor configuration for solar and b) the madness of energy pricing policy that fixes prices in favour of gas.
Given the mad fluctuations in energy prices over the last 4 years, it's also tricky to do a year on year comparison, but here's a summary. Between July 2019 and July 2021 our average annual consumption of gas was 27,395KWh, electric 3,251KWh. That compares with 18,000KWh for gas and 4,500 kWh electricity in the 'high' average consumption data on the Love Energy savings website. Our consumption is probably higher due to us living in an older property in a part of the country with colder, darker winters than most of the UK population. Based on this, we would expect our bills to be considerably higher than the figure quoted (£2,624 per year). In fact, we are paying £2604 per year, which suggests that we are saving money - but not massively (maybe £500 per year).
Was it worth it?
When the opportunity to join the trial came along, we were primed and ready. We were worried about the future of gas (and gas prices), intrigued by the technology, fed-up of biased reportage, and committed professionally to renewable energy and lower carbon living. Our most important considerations were that our home was cosy, that we were protected against future swings in gas prices and availability, that our carbon-footprint was lower, and that it was simple to run. We were happy to invest to achieve this.
We now have a reliably cosy home, with minimal 'tinkering' with the system (except for switching holiday mode on and off from our phones), and we have significantly reduced our carbon footprint. Our current energy costs are probably about £500 a year less than they would have been if we'd stuck with our gas boiler. I've nearly finished all the annoying little DIY jobs that needed doing post-installation ('one filler' is my new best friend), and the local cats seem to have finally learned not to jump onto the pump housing.
I'm pleased we did it, and would make the same decision again: performance is good, anxiety minimal, costs lower and climate impact brilliant. What is so frustrating is the madness of the energy pricing system for consumers. Scotland currently produces some of the cheapest renewable energy in the world from wind-farms, and yet the price consumers pay is tied to gas (there is a complicated logic to this - see here for an explainer). As the balance between renewables, storage and gas changes, this will hopefully change in the future... and we'll be ready when it does.
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