Finsbury Park - Deep Retrofit
Kitchen and dining view looking towards the garden with the greenhouse visible beyond
Vickers Architects were appointed to provide consultancy services during the construction stage of this deep retrofit and rear extension project to a Victorian terrace property. Our role involved reviewing the detailing and installation of the internal wood fibre insulation and airtightness membranes, ensuring the building fabric was breathable and the construction robust, a critical first step in creating a healthy home. A clear coating of 'masonry protection cream' was applied to the exterior of the brick. This helps prevent sources of external moisture from entering the masonry whilst still allowing the construction to 'breathe', thereby allowing any moisture within the wall to escape. In doing so, the dryer masonry construction has an improved thermal conductivity and it provides protection to the internal wood fibre insulation.
Rear view of the kitchen extension with a stained glass inspired facade
We assisted with the installation design and commissioning of the Mechanical Ventilation and Heat Recovery (MVHR) system, ensuring the set up was optimised for efficiency and comfort with near silent operation. Similarly, an Air Source Heat Pump (ASHP) located on the rear extension roof operates well below ambient noise levels and is barely audible. Ten solar photovoltaic panels are located on the front and rear roof pitches and a 5kW battery is located within the rear garden. The property has been disconnected from the gas network and now operates fully on electric.
Analysis of the property before retrofit estimated the heating demand to be 201 kWh/m²/year. We also considered the total energy use for the property which is referred to as the Energy Use Intensity (EUI). The pre-retrofit analysis indicated an existing EUI of 273 kWh/m²/year. The EUI estimate for the proposed retrofit works were calculated to be 24 kWh/m²/year. This is below the LETI and RIBA target of 35 kWh/m²/year. This is an industry recognised performance target intended to align with anticipated future legislation and sets out a trajectory to realise the significant reductions necessary by 2030 in order to have a realistic prospect of achieving net zero carbon for the whole UK building stock by 2050.
For context, the current 'business as usual' EUI for a standard new build dwelling meeting the minimal requirements of Building Regulations compliance would be 120 kWh/m2/year. The current 2021 regulatory guidance for 'Good Practice' on a new build is 60kWh/m2/year which is for a dwelling which does not use gas.
Within the first 6 months of occupation from January 2025 to June 2025, the total operating electrical costs averaged at £60 per month, which includes heating, lighting and all other electrical uses. Our early estimates indicate this is equivalent an EUI of 18 kWh/m²/year, although at this stage this does not include the energy used from renewables. We will be keen to revisit this once our client has occupied the property for a full year and collated a full set of data on their energy consumption.
For context, the current 'business as usual' EUI for a standard new build dwelling meeting the minimal requirements of Building Regulations compliance would be 120 kWh/m2/year. The current 2021 regulatory guidance for 'Good Practice' on a new build is 60kWh/m2/year which is for a dwelling which does not use gas.
Within the first 6 months of occupation from January 2025 to June 2025, the total operating electrical costs averaged at £60 per month, which includes heating, lighting and all other electrical uses. Our early estimates indicate this is equivalent an EUI of 18 kWh/m²/year, although at this stage this does not include the energy used from renewables. We will be keen to revisit this once our client has occupied the property for a full year and collated a full set of data on their energy consumption.
View from the extension towards the front of the house
Reception room and entrance hall
Access to a downstairs shower room and WC within the side return infill
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Front reception room
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Photographs by Anna Stathaki.
Project Team
Design Architect: Office S&M
Construction Stage Consultant: Vickers Architects
Structural Engineer: Tisserin Engineers
Services Engineer: DVJ Design
CDM: CDRM Services
Airtightness Testing: Heat Space and Light
Main Contractor: Dream 4 House
Services Subcontractor: Elite Renewables
Design Architect: Office S&M
Construction Stage Consultant: Vickers Architects
Structural Engineer: Tisserin Engineers
Services Engineer: DVJ Design
CDM: CDRM Services
Airtightness Testing: Heat Space and Light
Main Contractor: Dream 4 House
Services Subcontractor: Elite Renewables
