London-based architectural practice Knox Bhavan designed Threefold House, a new residential property in Teddington, south-west London. The low-carbon house is constructed on a brownfield site in a built-up area that was previously occupied by a disused warehouse. The contemporary home includes three courtyards and sits on a challenging 450-square-meter (4,844-square-feet) triangular plot, surrounded by other properties and a small car park.
The name Threefold House is a reference to the building’s “origami-inspired assemblage of geometrical planes,” explains Knox Bhavan. The site is bounded by a new 2.5-meter-high (8-feet-high) perimeter wall that recalls the former warehouse wall. Behind this, the property consists of three courtyards with single-story accommodation, a garage, and an upper volume that borders the street (the total gross internal area is 344 square meters — 3,703 square feet). “The single-story brick construction is tucked below and behind the top of the parapet wall, hiding the living spaces from the street,” says the studio. Located in a cul-de-sac, the home’s eaves and roof are in harmony with the height of the adjacent terraced houses.
Commissioned by the client as a home to retire in, principal rooms, including an open-plan living–dining–kitchen area, main bedroom, and a study, are placed at ground-level and “interspersed with gardens to enable aging-in-place,” says Knox Bhavan. The first floor is designed as an area for family and guests with three bedrooms, bathrooms, and a double-height space. As part of the home’s environmentally-driven spatial strategy, this level can be closed off, conserving energy when not in use.
Living areas are built around the three differently sized and strategically positioned verdant courtyards — the courtyards provide the home with natural light and ventilation and windows ensure extended views throughout the property. A courtyard at the apex of the triangular site serves as a private space for the main bedroom; a small rhombus-shaped courtyard in the center of the property offers an outlook for both the living area and study; at the site’s wide end, a large trapezoidal courtyard is accessed via the open-plan living–dining–kitchen area. A perforated wall in the main bedroom courtyard dapples the garden with light and provides glimpses to passers-by. The planted courtyards are also ideal habitats for biodiversity, creating a microclimate for wildlife and beneficial insects; moreover, they provide urban cooling.
Threefold House is built using a lightweight steel frame and engineered concrete slab with a timber-framed volume on the upper level. Delineated by a narrow clerestory, this volume is clad in dark zinc with clear and carefully positioned standing seams: “Each seam runs in the same plane continuously — from the external street-facing wall, up and over the pitched roof, and down onto the adjoining roof of the living room,” says Knox Bhavan. “The effect is that of a chamfered, zinc-clad box floating above the wall.” The home’s energy efficient strategies include: high levels of continuous insulation and airtight membranes; photovoltaic panels on the zinc roof (powering an air source heat pump and electric car charger); timber brise-soleil to prevent overheating; and a green roof to reduce internal temperatures in summer and provide insulation in winter.
Knox Bhavan designed Threefold House before the introduction of a 2030 Climate Challenge developed by RIBA (the Royal Institute of British Architects). The challenge sets targets in relation to reducing operational energy, embodied carbon, and potable water. The studio does however show figures that are commensurate with 2025 targets: operational energy use (total energy and heating consumption) is estimated at 49.6 kWh/m2/yr; the whole building embodied carbon is 481 kgCO2eq/m2 (a 10 percent increase on cradle-to-practical completion is factored in to account for MEP) — this exceeds the 2030 RIBA benchmark; the potable water use is estimated at 106.5 l/p/day. For Knox Bhavan, the studio considers Threefold House to be “an exemplar project of low-carbon design, reimagining a challenging brownfield site, and outlining a path to realizing the ambitions of the 2030 Climate Challenge.”
Threefold House is a winner of a 2023 RIBA London Award.
