Climate Friendly Retrofit Part 9: System Performance, Price Cap, & Fuel Poverty

Josiah Lockhart
4 min readMay 3, 2022


After having not updated for a little while, I wanted to take a wee bit of a time to summarise where we are at with our retrofit that spring has arrived. As always, if you’ve missed earlier parts of this story, you can check them out here.

The winter period has been a hectic one for us in finishing off all our systems, including our heating system which was rushed as our gas boiler broke in the middle of December! What this does, is ease some of our retro-fit pressure on this year, setting up the rest of 2022 for painting, decorating, and beginning to explore climate adaptation techniques. You may ask, what is the full list of decarbonisation upgrades?

· Full insulation including underfloor, cavity wall, room in roof, and loft

· Upgrading outdates single glazed windows and skylight to triple glazed

· Intensive draught proofing

· Replacing open fire with sealed clean burn wood stove

· Installation of 5kwh solar array along with 10kwh of battery storage

· Installation of a Mixergy Hot Water Tank

· Installation of entire MyEnergi suite to manage our energy and divert our solar to the right place

· Installation of a Herschel Infrared heating system throughout the house

As we are all aware, across the UK energy prices are going crazy, and with our leaky housing stock, those prices are amplified in homes that were built for a different time, particularly where upgrades and general maintenance haven’t been carried out correctly. This combined with other cost of living issues is already pushing millions more into fuel poverty. After a few conversations with people exploring how to tackle this over the past couple of months, I’m keen to further use my own project as a way to demonstrate how mass retrofitting can tackle both the climate crisis and alleviate parts of fuel poverty.

One of the big problems we face in my own project is finding comparative data for savings as we started this project after having moved into this house during lockdown which had been vacant for a couple of years. Every time we make an upgrade or change, we are limited in what we can compare it to. But April, is close to being a median month for us, and we had 4 guests staying with us for 2 of the weeks putting all of our systems to the test. With all those caveats, now that our systems are fully installed and we have electrified everything, how is our house performing when compared to the current energy prices?

In total, our house consumed 671 Kwh in the Month of April. This is higher than the average house, but we’re now 100% electric without the need of gas, charge the car at home periodically overnight, and had 4 extra guests stay for half the month with extra need for heating and the use of our power shower. But despite that, we were able to save over £157 through the use of our systems when compared to the April price cap tariff.

On the price cap, those 671kwh would have cost us just over £204 if we were on a flexible tariff, but with our solar panels, we were ablet to reduce that down to only drawing 324kwh from the grid. Combining our Octopus Go time of use tariff with out battery system and Mixergy hot water tank, 284 of those kwh were consumed at our 7.5p/kwh tariff reducing our energy bill to £41.60. On top of that we sold excess energy to the grid and made £5.56 further reducing our net spend to 36.04. Within those numbers there is also 468mi of overnight car charging for a total cost of only £8.18. What makes it even more noticeable is comparing that to our usage last April (401kwh Electricity and 3849kwh Gas)which would have cost £412 at today’s rates.

If April is a median month for us, that means we have reduced the payback for our entire system from a little over 9 years to 5.8 years, nearly the length of zero interest loan from the energy savings trust.

What April’s energy use in my own home demonstrates is that the technology to do this is here, but isn’t yet equipped to be delivered at scale, and to truly address the poverty side of the equation, we need to find ways of making this process quick, efficient, and equitable as not everyone is a homeowner, has the spare cash, or can qualify for/afford a loan to do this,

Over the next couple of months, I’m going to pick this blog back up where I left off a couple months ago and have been working with some of the manufacturers on really getting into the detail of their products’ performance. As I always say, every house is different, the solutions I have chosen are not a once size fits all, but have all been chosen due to unique parts of my house.

If you’ve taken the time to get this far… thanks and keep an eye out for the next one.