Monument preservation and energy-efficient renovation are often seen as opposing goals. Yet several projects prove otherwise. One compelling example: the Cologne architecture firm HPA+ successfully transformed a listed residential building in Cologne-Ehrenfeld, creating modern, open-plan living spaces within its historic walls while integrating renewable energy sources that significantly improve the building's environmental footprint.

This two-axis, two-storey residence with gabled upper floor was designed by architect Rudolf Brovot in 1909. The owners envisioned converting it into a family home for five while upgrading its energy performance—and crucially, they wanted a contemporary open-plan layout that would honor and highlight the building's historic character. The ground floor houses the kitchen and living areas, the first floor serves the three children, the second accommodates the parents, and the newly renovated attic functions as a home office. Working closely with the heritage authority, the architects made strategic interventions rather than sweeping demolitions: selective wall openings and interior glass panels now frame visual connections between spaces, while preserved and carefully restored flooring throughout the open living, cooking, and dining area subtly echoes the home's original spatial divisions. The original attic staircase gave way to a sculptural curved spiral staircase that references the restored historic wooden staircase with its turned banister. The necessary ceiling opening and expansive roof windows not only allow emergency egress but flood the stairwell with natural light down to the ground floor. As part of the larger historic ensemble reflecting the original streetscape of the "Neu-Ehrenfeld" district developed during its construction era, the home's façade and front garden required careful coordination with neighboring buildings. A once-removed balcony was reinstated on the garden elevation. To improve the building envelope's energy performance, the monument authority approved window replacement—provided they authentically replicate the originals. An air-source heat pump now delivers sustainable heating, powered entirely by rooftop solar panels that integrate seamlessly into the roof tiles, earning approval from the heritage authority. It marks the first time in Cologne that a protected historic building has been powered by integrated photovoltaic systems.

www.hpa.de

Photography:
Detlef Podehl
www.podehl.com

(Published in CUBE Cologne Bonn 02|24)