Terry’s deep retrofit of his Frome home

Eco refurbishment and decarbonising a late Victorian end of terrace house in Frome by Terry Pinto.

Our home was a cold, draughty house 3-bedroom house that had been poorly refurbished over its lifetime having been built around 1880. Its construction was 50cm thick stone walls that were plastered on the inside, with a tiled roof that had minimal insulation. The boiler was approximately 18 years old and was on its last legs. The house has an impractical cold ground floor bathroom and an awful plastic conservatory that hindered access to the small garden.

The choice we had was do we move or refurbish the house? The plus benefits were that our house was near the town centre where my eco architects practice is based. It was also close to the local fields and countryside, so its location was ideal. Luckily, we had an £110K inheritance from my wife’s mother’s estate when she passed away. We used this to finance the eco refurbishment project.

As an “eco“ architect I wanted to practice what I preach so we used our home as an exemplar model for a practical eco refurbishment. We started on this journey in mid-2020.

The key elements of the project were to:

1. Improve the insulation values of the house.
2. Reduce the draughts.
3. Take us being reliant on fossil fuels and especially gas for our hot water needs.
4. Reuse as much as possible so that we did not create more carbon in the construction process.
5. Where possible, use materials that had as low an embodied energy as possible. Though this was a balancing act against cost and thermal efficiency.

As the house is in a conservation area, we could not practically insulate the house from the outside. Thus, we had to strip the plaster from the internal face of the external walls back to the stone. We then fitted a separate stud wall that was 10cm deep. Between the studs filled it with 75mm foil-backed expanded polystyrene insulation( EPS) with an 2.5cm air gap between the stone and insulation to stop any condensation issues. On top of this, we laid the plasterboard.

For the ground floor, we lifted the floorboard and fitted foil insulation between and over the floor joists with a new solid larch timber floor fitted on top. We also ensured that the floor void was ventilated to stop any condensation issues.

For the roof, we stripped back the attic plasterboard and fitted 100mm of foil-backed eps insulation with a 5cm air gap between that and the underside of the existing felt which was in good condition.

All the poor quality draughty UPVC windows were replaced with good quality high-performance triple-glazed aluminium windows by CPB of Corsham.

The extension was built with the same insulation but in more quantities. This was so it exceed the insulation values of building regulations at the time.

By insulating the house and replacing the glazing, this stopped the drafts. However, we did not want the house so airtight that it created internal condensation, so a sensible approach was taken. We also introduced a lobby. When the front door is now opened, all the heat does not escape out of the house.

We had insulated the house above building regulations insulation values. It therefore made practical sense to replace the gas boiler with a Vaillant Aerotherm air source heat pump. This meant we had to have new smaller radiators, as we had insulated the house. It does work differently from a gas boiler. The water temperature is 48 degrees Celsius, whilst a gas boiler is 95 degrees. However, this is plenty hot enough for a piping hot bath and to heat the radiators due to the amount of insulation. We received a government grant of £7.5K from our overall cost of £9.5k. This grant is now capped at £5k, though I do not know how much longer it will last.

Finally, an older gas boiler operates on 50% efficiency, whilst our air source heat pump has an efficiency of 250%. So for every 1.0 KW of energy a gas boiler puts in, you get 0.5 KW back, whereas for our system we get 3.5KW back!

We demolished the horrible old extension and rescued the footings and slab which saved a significant amount of material. We also rescued a lot of the sanitary ware and the old Victorian floorboards and reused them all throughout the house. The old bricks and tiles were reclaimed and reused in the garden. We also minimised the amount of demolition.

Most of the construction materials consist of timber in one form or another. This means that we have sequestrated a lot of carbon from a natural renewable source instead of artificial materials which may have used a lot of fossil fuels. The only item that did not fit in with this policy was the insulation. As we have a small space, the artificial insulation was thinner, performed better size for size and was cheaper. The aluminium windows now use 99% recycled aluminium, so this was deemed an acceptable compromise.

Our only regret was not installing underfloor heating as this works better with an air source pump. Bar that, we have a home that is now futureproofed and will actively emit less carbon than even an average new build house, but we still have a lovely old Victorian period house with an open fire. Overall, we have spent around £150K, though this includes a large kitchen extension with plumbing new solid oak bespoke kitchen, whole house eco refurbishment and remodelling including new electrics and a re-landscaped garden