House for Two Photographers

As the grid decarbonised and u-values improve, energy in use is increasingly less significant than embodied carbon, which happens before a building is occupied and is responsible for 11% of global emissions. Victorian houses rely on masonry for foundations and load-bearing walls, and timber for floors and roofs, yet today it is commonplace to use steel and concrete when building an extension or a loft conversion even when timber could be used. This project re-invents the terrace house extension to maximise the use of timber, reduce embodied carbon and allow for end-of-life reuse. For the foundations, screw piles are connected by steel beams bolted to be easily dismantled. A rainwater harvesting pond doubles as a retaining structure made of brickwork rather than concrete. The superstructure is entirely timber, designed to char to comply with fire regulations. A 7m long oak glulam beam on solid oak posts is the primary element, supporting the old brick outrigger above. This system generates the architecture, with a circulation/seating area enclosed by a secondary portal frame supporting the new party wall, and centred on the existing access doorway to the old house. The roof structure radiates from this central spine, creating a clerestory window along its length. Inspired by Japanese carpentry, connections are simple and demountable, with elements resting on top of or next to one another. The beams are exposed and the plywood deck of the roof forms the ceiling, eliminating the need for plasterboard. All the glazed elements are timber framed. The floor insulation is sheep wool and the wall insulation is wood fibre. Embodied carbon emissions (A1-A3) are 352 kgCO2e/m2 which is about half the emission of a standard extension. If sequestration from the extensive use of timber is taken into account emissions are further reduced to 158 kgCO2e/m2.