Cadogan Terrace Retrofit

Cadogan Terrace is a mid-19th century, three-storey terraced house (plus basement) located in East London, originally constructed circa 1850. The building presents a layered architectural typology, combining original Victorian fabric with incremental 20th-century interventions, reflecting its long-term adaptive use.

The primary structure comprises solid load-bearing brickwork in Flemish bond, with retained timber-framed floor assemblies and a distinctive butterfly roof form, currently finished in fibre-cement slates. Internally, the building exhibits a hybrid structural condition, with a combination of timber stud partitions, solid masonry walls, and brick-infill construction. The basement retains a central spine wall in solid brick masonry.

Later additions extend to the rear, incorporating a ground floor kitchen and bathroom extension constructed with concrete floor slabs and lightweight roof build-ups. The original upper floors remain predominantly timber-framed, while all existing fenestration consists of single-glazed timber sash windows, likely original to their respective construction periods.

The site occupies a narrow, east–west oriented urban plot. A complex historical boundary condition has resulted in an irregular land division at the rear, with portions of garden space exchanged between neighbouring properties over time. The house benefits from strong daylighting conditions, with west-facing frontage overlooking Victoria Park and mature tree-lined views to the rear, supplemented by a small rear yard and first-floor terrace.

Design Approach

As a building with a complex historic layering and previous non-residential use (former post office), the project adopts a conservation-led retrofit strategy that balances heritage retention with contemporary spatial performance.

The existing cellular plan typology, characteristic of Victorian domestic architecture, is selectively reconfigured to improve spatial permeability, daylight distribution, and functional connectivity between front and rear of the building. Rather than wholesale reorganisation, the strategy focuses on targeted interventions that unlock spatial quality while maintaining the legibility of the original fabric.

The design methodology is grounded in a material honesty approach, where new insertions are intentionally differentiated from existing structure. This creates a readable architectural palimpsest, allowing old and new elements to coexist without imitation or pastiche.

Material reuse from the existing building is prioritised wherever viable, forming part of a circular retrofit strategy that reduces embodied carbon while maintaining continuity of material narrative.

Daylight optimisation is a central driver of the proposal, with particular focus on enhancing solar penetration to the ground floor through reconfiguration of rear roof geometry and strategic spatial opening within the plan.

Sustainable Design Strategy

Embodied Carbon Reduction

The project adopts a carbon-first design methodology, addressing both operational and embodied emissions in response to the climate impact of the built environment, which accounts for approximately 40% of global CO₂e emissions.

The strategy prioritises:

• Retention of existing structural fabric where feasible

• Specification of low-carbon and biogenic materials

• High levels of reclaimed and reused material content

• Local sourcing to reduce transport-related emissions

• Selection of manufacturers operating on renewable energy supply chains

Bio-based materials such as timber, wood fibre insulation, cork, and hemp are prioritised for their carbon sequestration potential, enabling the building fabric to function as a temporary carbon store.

The embodied carbon target is aligned with the RIBA 2030 Climate Challenge threshold of <300 kgCO₂e/m², with an aspirational objective of achieving net-negative embodied carbon performance through material sequestration.

Operational Energy Strategy

The retrofit prioritises fabric-first performance upgrades to minimise operational energy demand. Key interventions include enhanced thermal insulation, improved airtightness, and reduction of thermal bridging.

The design targets operational energy use of <35 kWh/m²/year, in line with RIBA 2030 performance benchmarks.

The building will be fully electrified, operating on a low-carbon grid with progressively reducing carbon intensity. Space heating demand - typically the dominant energy load in UK housing - is significantly reduced through envelope optimisation.

On-Site Renewable Energy

A photovoltaic array is integrated within the south-facing butterfly roof geometry, optimising solar exposure and roof form efficiency. The system provides on-site renewable electricity generation, offsetting grid demand and enabling seasonal energy balancing between export and import cycles.

Additional Sustainability Measures

Indoor Environmental Quality
All internal finishes are specified to minimise VOC emissions, prioritising non-toxic, low-emission materials to improve indoor air quality and occupant health.

Water Efficiency
Water consumption is reduced through low-flow fixtures targeting <75 litres per person per day. Rainwater harvesting from the butterfly roof is proposed for irrigation reuse, with potential for decentralised storage integrated within the rear terrace zone.

Urban Biodiversity
The landscape strategy introduces native and pollinator-supporting planting within a constrained urban footprint. Biodiversity enhancement is further supported through integrated habitat features, including bird nesting provisions, insect habitats, and bat roost integration within the building fabric where feasible.

Location: East London, London Borough of Tower Hamlets

Property type: Victorian end-of-terrace

Scope: Deep retrofit and partial extension of a mid-19th century Victorian end-of-terrace house in East London, focusing on fabric performance upgrades, spatial reconfiguration, and low-carbon systems integration to transform the building into a high-efficiency, climate-responsive home.

Key Features

• Deep retrofit

• Significant energy reduction

• Retention and reuse of existing building fabric

• Selective spatial reconfiguration

• Butterfly roof with PV integration

• Low-carbon material strategy

• Improved daylighting strategy

• High-performance building envelope targeting RIBA 2030 energy standards

• Heritage-sensitive design approach

Project Results

• Up to ~75% reduction in space heating demand

• Significantly improved building envelope performance

• Lower operational carbon emissions

• On-site renewable energy generation

• Reduced embodied carbon

• Improved daylight quality and spatial comfort

• Enhanced functional layout

• Future-ready low-carbon home