Waltham Forest Council has been taking steps to address the climate emergency for years. To meet a net zero target by 2030, future initiatives must go further and use innovative technologies.
Homes are the biggest carbon emissions contributor, so retrofitting a traditional Victorian terrace shows residents the changes they can make to their homes to save energy, money and reduce their carbon footprint.
Waltham Forest Borough Council appointed long-standing partners Aston Group to manage the retrofit of a council owned property, into its first-ever eco show home. 47 Greenleaf Road as a typical Victorian terrace built in 1902 with a poor energy performance. A report published by Waltham Forest Council in 2019 highlighted that 51% of the borough’s carbon emissions were generated by residential homes. The same report also revealed that 14.6% of homes in the area were fuel poor households. New-build properties with energy-efficient technology are only part of the solution. With 70% of Waltham Forest’s 107,216 homes pre-dating 1944, it’s vital to find a way to reduce carbon emissions from existing homes, through retrofitting. The annual heat demand from this home is estimated to fall from 17,219kWh to 7,995kWh per year, while the EPC banding will rise to from E to A.

Thermal upgrades -making the house warmer
Wall insulation
External wall insulation (EWI) was installed to the side and rear elevations of the property, using a 90mm EPS slab with a topcoat of render. EWI was not feasible on the street elevation to avoid loss of character to the property, therefore, Internal wall insulation (IWI) was installed to this façade using a 57.5mm insulated plasterboard.
Roof insulation
The roof was upgraded to 300mm of mineral wool insulation (between and above joists). This reduced heat loss through the roof by 50%.
Underfloor insulation -installed by a robot
Floor insulation was installed to the main suspended floor via the Q-bot insulation system. Q bot uses robots to spray insulation under the floor with minimal disruption, making the room warmer. This reduced heat loss through the floor by up to 74%.
Windows – new glazing
Around 10% of heat is lost through windows and doors, so new high-performance double glazing was installed into the existing window frames. The new glass has a low-e coating to increase its insultation qualities. It allows light and heat in doesn’t allow it to leave, trapping heat within the home.

Service upgrades
Ventilation
To further reduce heat loss and improve internal indoor air quality, a mechanical ventilation system with heat recovery (MVHR) was installed to provide fresh air throughout the house. Installed in so-called ‘wet areas’, such as kitchens and bathrooms, an MVHR recovers heat from water vapour and uses it to keep the house warm. The heat from the extracted stale air is drawn through an air-to-air heat exchanger located within the heat recovery ventilation unit and is used to warm incoming fresh, filtered air for living rooms and bedrooms. In some cases, around 96% of the heat generated can be retained.
New heating system
The old gas boiler has been replaced with an air-source heat pump, and hot water cylinder. While it is a complex system, in simple terms, it’s the opposite of a domestic freezer. The unit sits outside and harnesses heat from the outside air and pumps that into the central heating system to keep the property warm. It even works at temperatures as low as -15˚. The unit uses a small amount of electricity to power the system, which at 47 Greenleaf Road, is supplied by solar photovoltaic (PV) panels with battery storage so the system is entirely sustainable.
There’s little maintenance involved, and no annual gas safety inspections required. The system has an expected life span between 20-25 years
Solar photovoltaic system
A 3.9 kWp solar photovoltaic system has been installed, with associated battery storage. This is capable of producing approximately 2,850 kWh of electricity per year and reduces carbon emissions by 853 kg per year. The battery allows power to be stored for overnight use.
Wastewater heat recovery
A heat recovery system has been fitted beneath the bath. This works by taking warm water and uses it to heat incoming cold water.

Results
Comparisons and analysis have been undertaken to compare the thermal performances between the original building and the design performance (calculated using the government approved SAP methodology). A regime of testing was also undertaken to validate the improvements.
The original building reported an EPC E, after works the building has now achieved an EPC A.