1930s semi, 3 bedrooms, ~ 110m2. Single floor extension to the back containing a shower room and living room.
Overview of fabric (walls/roof/floors/windows) BEFORE any improvements – various double glazed pvc windows but with some blown , and probably at least 20 years old so not very effective. Chimney on rear roof was not used and could be removed to make more space for solar panels. Solid brick walls - no cavities
Types of Insulation installed BEFORE/AFTER – no wall cavity. 300mm of loft insulation.
External cladding. Existing render needed attention. Were quoted told £9000 to re-render vs. £15,000 to fit 95mm external insulation. Didn’t want disruption of putting up internal insulation and then making rooms smaller. We clad the exterior with 95mm of EPS (Atlas Etics) with a u-value of 0.22.
Windows replaced with PVC double glazing to all windows except for on extension
EPC rating BEFORE and AFTER improvements – D67 before and said potential B82. After all work B87
Main energy sources used for heating BEFORE (gas/oil/electricity/solid fuel). Gas central heating, and for water. Gas hob, electric oven. Wood burner in sitting room just used in evening
Major changes in use of energy / energy tariffs –Electric hob installed before work started. Builder doing insulation capped gas. Switched to Octopus and got them to take away the meter to avoid getting the standing charge. Builder accidentally damaged the gas pipe so Cadent came out to cap by the house. A year later Cadent got in touch to come and check the gas and make sure all ok. Got in touch with Cadent before all the work to see what we should do and they wanted to charge ~£3000 to disconnect! Builder said just wait. On Octopus Flex with 3 different tariffs through day for both import and export.
Renewable energy systems installed (Solar water, solar PV, batteries, heat pumps, wind turbines etc –
7KW Vaillant ASHP installed. Sits on back of house. Replaced or swopped round a couple of radiators as not big enough for room. Existing pipework was adequate. Someone recommended to check if existing pipework is adequate for a ASHP, to turn down the flow temperature on the gas boiler to 45C and see if was still able to warm the house. Was ok. Have an expansion tank installed in the loft which was a bit of a nightmare to get up there and have since found out that this is not vital to the system in most situations.
9 solar panels fitted, 5 on West facing roof, 4 on south facing roof.
5kwh battery installed. Do wonder if should have had a bigger battery installed but so far happy with this. Battery and inverter fitted in garage.
Comparison of Energy usage In £££ / KWH BEFORE / AFTER found it really difficult to make a comparison but our old energy bills said ~ 2,500-3000 KWH electric annually, and 11,000 KWH gas. Before work, central heating would go off once we lit woodburner at night in winter. July 2024 to end June 2025 used 4674 KWH. And have exported 2645 KWH in same time. The feeling in the house is so different to before. As we just used woodburner in sitting room at night in winter the rest of house was cold and was suffering with damp in places. We now have a much more comfortable house and feels much better for the fabric of the house.
Plans for further decarbonisation - e.g. battery EVs & charging stations, offgrid power – wonder about putting 2 or 3 solar panels on garage roof but would need to make
sure National Grid are happy to increase and that it wouldn’t need to much more supporting equipment that might make it not economic. Need to box in ASHP equipment in bathroom
Additional information
Installation narrative with photos (PDF, 804kB)
