Phase 1 - Understanding the existing profile of the home and identifying opportunities for improvement
Tom, a resident of South East London, decided to retrofit his 1910s semi-detached Victorian house after experiencing several very chilly winters.
His goal was to improve the warmth and energy efficiency of his home. The project evolved into a full electrification, which included disconnecting mains gas, installing solar panels, inductive cooking, and an air source heat pump.
The property already had underfloor heating on the ground floor and internal wall insulation, but upstairs, there were significant issues with 9″ uninsulated Victorian brickwork on all external walls, barely insulated loft space, and single glazing on the rear of the house.
To address these issues, Tom enlisted the help of a heat engineer and an efficiency consultant, who conducted a survey of the property. The results showed that the 30kw gas boiler would be replaced with a 6.5kw heat pump.
Installing insulation and double-glazed windows
The first step was to remove and replace all of the leaky glazing with Low-E, argon-filled double glazed, timber sash windows to match the age of the house. Then the retrofitting process began.
The upstairs carpets were lifted, and 2×4″ wood frame structures were produced on the external walls to create a frame for the insulation cut-outs. The PIR insulation was then cut and pushed in, followed by plasterboard, skim, and decoration.
All of the upstairs radiators were replaced and upsized to reduce bills, given that the heat pump runs more efficiently at a lower temperature.
Installing a heat pump and hot water tank
Finally, the heat pump, a 5kW Vaillant Arotherm, with a 250l hot water tank, was installed. On the roof, 5kw of solar PV was installed, with a hot water diverter and an EV charger, ensuring any excess generation went into hot water and free miles in the electric car.
As there was no need for the mains gas connection, the gas supply was capped, resulting in savings on not having a daily standing charge.
The results - a warmer home and lower bills
Tom has been very pleased with the results, reporting that the temperature stays consistent throughout the day, even on a winter day. The heat pump has been mature and efficient, providing over 400% efficiency, which means it is cheaper to run than a gas boiler and is emissions-free too. The solar panels reduce bills and provide plenty of surplus energy on a sunny day, enough to export to the grid and get a small return.
Tom did encounter some teething problems with airflow around the heat pump, but those are due to be resolved when the heat pump is moved to an improved location. The heat pump also has the added bonus of being able to cool the house in hot summer months.
Insulating upstairs meant redecorating each room, which was time-consuming but worth it as part of a larger project. Tom is very satisfied with the improvements to his home and recommends this type of eco-retrofit to others looking to improve their home’s energy efficiency
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