Adrian James Architects has completed Copper Bottom, an imaginative and sustainable zero-carbon copper-clad home in Oxford, England. Designed and built as a family residence by and for architect Adrian James, this dynamic sculptural home is perched on an elevated site, offering views of Oxford’s historic spires. A truly curious abode, it features a copper carapace that gives the exterior an origami-like appearance. This carapace serves as a brise-soleil on three facades and a porch on the fourth.
Copper Bottom’s design is an ode to this exceptional metal, one that is aesthetically appealing, durable, lightweight, and recyclable (the copper used on the home is also recycled). Moreover, copper requires very little maintenance and its excellent thermal conductivity contributes to a building’s energy efficiency. Adrian James describes the finish on Copper Bottom as “a slight variation on the standard pre-patination — a less turquoise and more lime version of verdigris.” The architect adds: “Copper Bottom is situated on a lush site, surrounded by mature trees and wildflower meadows. We have chosen a finish that harmonizes with its verdant setting.” This verdant setting played a crucial role in selecting an ideal location: for James, the plot had to be elevated enough to provide panoramic views, situated at the end of a road, and within cycling distance of Oxford’s city center, thereby minimizing car usage.
Beneath its origami-esque copper carapace, Copper Bottom is in essence a two-story cuboid box with a sloping lid. Adrian James offers two reasons for this: “Firstly, the form factor. It’s best to keep houses as compact as possible to minimize the ratio of skin to volume. Secondly, airtightness. It’s better to avoid complex envelopes at the airtightness line to ensure the structure’s integrity.” The home’s two-story, cuboid shape is especially suited to the site. Living spaces and bedrooms are oriented towards the south-east, enjoying the warmth of the sun and views. The service areas are positioned in the opposite direction.
Copper Bottom’s superstructure is constructed from prefabricated Structural Insulated Panels. These wide softwood studs consist of a layer of insulation sandwiched between two structural oriented strand board (OSB) facings. “This creates an envelope with the requisite U-value and airtightness to conform to Passivhaus standards,” says James.
The key role of the structure’s copper carapace is to provide solar protection. To prevent excessive solar gain in the home’s south-facing aspect, with its generously proportioned windows and doors, the angled roof extends outwards. Adrian James describes the home’s east- and west-facing sides as having a “creased bulge” — this creates deep reveals for the windows on either side, protecting them from the low morning and evening sun. The bulge runs along the building’s north face, where it provides a porch over the home’s entrance and plant room doors. The bulge also ensures the upper part of the building is at a canted angle, reducing its visibility to neighbors. To finish the home’s outward appearance, augmenting its curious comportment, James added two “ears” that have a certain “hint of zoomorphism about them,” says the architect. The quirky zoomorphic additions are ventilation stacks, expelling hot air on warm summer nights and drawing cooler air in.
Copper Bottom’s angled roof has a slope of seven degrees, ensuring its 37 photovoltaic panels are positioned in the most efficient manner to maximize energy production (the panels are also not visible to neighboring properties). This PV array generates up to 16 kilowatts of power, providing renewable energy in excess of the home’s modest demands.
For Adrian James, sustainability was the key driver in the design of the family home. The architect’s aspiration is that Copper Bottom becomes one of the most holistically sustainable dwellings in the region, if not the entire country. A zero-carbon home, Copper Bottom excels at a number of sustainability parameters, including: minimal embodied energy, energy efficiency (via an air source heat pump and Mechanical Ventilation with Heat Recovery), and a low-carbon construction footprint (the site allowed for shallow foundations with a minimal use of concrete). Additional sustainable measures include a large rainwater harvesting tank and a focus on biodiversity.
The home’s interior is spacious and light. A lofty, open-plan ground floor flows around a luminous double-height gallery at the heart of the house. A substantial, exposed purple brick pier serves as a hearth, stair wall, and thermal heat sink, contributing to a consistent temperature throughout the year.
Copper Bottom is designed with longevity and adaptability in mind. For instance, the ground floor, with its wide corridors and doorways, can be easily reconfigured to accommodate wheelchair use.
