Horizon House by ONUS: Net-Zero in Syros

ONUS Architecture Studio has completed Horizon House, a net-zero energy residence nestled into the sloped terrain of Syros, Greece. This award-winning project blends minimalist architecture with regenerative principles, creating a living environment that restores rather than depletes. Horizon House recently won the 2025 Architizer A+ Award for Best Sustainable Residential Project, a testament to its holistic integration of design, ecology, and technology.

Architecture Embedded in the Cycladic Terrain

Built along a steep site overlooking the Aegean Sea, the residence is partially subterranean, responding both to the topography and the local climate. This strategy minimizes the visual impact while enhancing thermal performance. Excavated stone was reused for structural walls and cladding, rooting the house materially into its landscape. Alongside raw concrete and reclaimed wood, the architecture presents a low-carbon aesthetic anchored in place.

Spatial Design and Environmental Performance

Horizon House stretches along a linear axis parallel to the sea, with all interior spaces facing south for optimal views and passive solar gain. The northern façade remains sheltered, supporting thermal comfort during strong island winds. The L-shaped pool reflects the geometry of the house and serves both as a cooling feature and a visual bridge to the landscape. Skylights, operable windows, and deep-set openings ensure natural ventilation and daylight, reducing dependency on mechanical systems.

Off-Grid Systems and Circular Resource Use

Energy autonomy lies at the heart of the design. Micro wind turbines and a geothermal system manage the energy needs, while a green roof integrates a blue roof water-harvesting system. Rainwater is collected, filtered, and reused; greywater is treated on-site for irrigation. These strategies enable the residence to function completely off-grid, showcasing how modern homes can support circular living models without compromising comfort or elegance.

Landscape as an Ecological Infrastructure

The landscape design reinforces the regenerative mission of the project. Native species were selected for their resilience and ecological benefits—attracting pollinators, stabilizing soil, and enhancing biodiversity. Trees and shrubs are strategically placed to offer shade and wind protection, creating a favorable microclimate around the house. This living layer blurs the line between built form and nature, contributing to long-term environmental restoration.

Inside, Horizon House favors clarity and continuity. Spatial planning is guided by sunlight and views, while materials express their own textures without ornamentation. With its fluid transitions between indoor and outdoor zones, the house becomes a seamless extension of the island terrain.

Horizon House by ONUS Architecture Studio is more than a residence—it is a model of how architecture can work in harmony with nature. By embracing passive systems, local materials, and ecosystem-based strategies, it offers a vision for regenerative living in vulnerable landscapes.