This two-storey home in one of Cologne's most coveted neighbourhoods had fallen into disrepair and lacked any insulation whatsoever. Rather than demolish the 1960s structure—a fate that befalls too many buildings—the owners chose sustainable renovation instead. Cologne-based sopha architekten replaced the original gabled roof with a set-back penthouse level, reshaping the entire façade with expansive window walls and crisp white plaster to create a timeless elegance.

Building codes and required setbacks dictated a terraced, harmoniously proportioned form with two connected dwelling units. The greatest hurdle came during transformation: the existing top floor couldn't support the additional weight, so it was removed entirely. A new floor plate was then suspended from beams in the penthouse zone. The timber-framed addition was prefabricated off-site in modules and hoisted into place by crane in minimal time. To achieve KfW Energy Efficiency House 55 standards, every component required extensive insulation. Critically, the owners rejected conventional thermal wrapping systems in favour of sustainable alternatives: excepting only the foundation perimeter insulation and roof waterproofing, every material throughout the building meets ecological standards. The façade and roof insulation comprises wood fibre boards and blown cellulose. A custom-tinted, light-coloured lime plaster provides the exterior finish. The interior layout was equally transformed to create flowing, open transitions to the outdoors—flooded with natural light and framing views. Both ground and top floor living spaces extend generously via floor-to-ceiling sliding glass walls featuring fully glazed corners, with solar control glass providing selective shading. Energy sustainability proved equally essential: a pellet stove and water-fed open fireplace supply both heating and domestic hot water, virtually eliminating dependence on fossil fuels.

www.sopha.de

Photography Credits:

Kurt Steinhausen
www.kurtsteinhausen.de

(Published in CUBE Cologne 02|23)