A white 1960s bungalow with a hipped roof sits nestled within a generous, idyllic garden landscape of mature trees. This was the landscape facing ZHAC Zweering Helmus Architektur + Consulting, the Aachen-based firm tasked with modernizing the structure and expanding it for additional living space. Demolition and rebuilding were never an option—the owner, who had spent his childhood in this neighborhood, was committed to preserving the harmonious relationship between the house and garden that had evolved over decades.

The homeowners wanted a separate master bedroom, ensuite bathroom, and an additional double garage. These additions were unified in a single extension on the southwest slope, seamlessly attached to the original bungalow without disrupting its essential character. The single-story, polygonal addition aligns perfectly with the main structure – the distinctive roof line of the bungalow continues unbroken at the same height into the cantilevered roof of the new wing. Anchored into the slope, it actively supports the terrain. Toward the garden, floor-to-ceiling glass walls open the new bedroom, bathroom, and dressing room directly to the existing pool, dissolving the boundary between inside and out. Imagine waking and stepping straight into the water – what better beginning could there be? To keep the addition visually recessive behind the main building, it's finished in raw black concrete. Portions of the largely transparent façade feature vertical wooden louvers with dark window frames – their delicate rhythm plays against the strong horizontal roofline and echoes in the flush-mounted garage door and new entry portal of the bungalow. The existing structure received the same thoughtful attention as the garden, refined both inside and out. Key design details were carefully extracted and, where appropriate, reinterpreted to honor the home's original spirit.

The energy retrofit centers on a geothermal water-source heat pump that sustainably heats both house and pool. A rooftop-integrated photovoltaic system generates the electricity needed to operate the pump – largely self-sufficient. Summer cooling for the bedroom comes via air conditioning. Building automation orchestrates nearly every controllable system through a unified smart home platform.

www.zhac.de

Living space: 238 m² (excluding terraces)
Plot size: 2,938 m²
Construction period: 2.5 years (extended due to COVID-19)
Construction method: Solid masonry
Energy concept: Geothermal heat pump

Photography:
Annika Feuss
www.annikafeuss.com

(Featured in CUBE Cologne Bonn 3|24)