French architecture firm ALTA has completed an ambitious office development project on Chemin du Bois Harel, a transforming site located between Rennes and Saint-Jacques-de-la-Lande. The Bois Harel Tertiary Complex, covering 6,920 square meters and completed in 2025, represents a new vision of sustainable office architecture designed to bridge daily life with the broader landscape while maintaining quality of life standards.
The site itself tells a story of transformation, having once been a market gardening area marked by the Crublé greenhouses, which closed in 2004. This reconfigured territory now sits at the intersection of contrasting realities – rural landscape dotted with scattered housing to the west, and the busy Rennes ring road with constant traffic flow to the east. ALTA envisioned a connecting architecture that is both simple and contemporary, designed to harmonize these different scales.
The project is organized around two three-story buildings positioned atop a shared underground base that houses parking facilities. Designed to meet French 5th category ERP (Establishment Receiving Public) standards, the complex includes 170 parking spaces, several of which are equipped with electric vehicle charging stations. The development also features secure bicycle storage facilities to promote sustainable mobility options for occupants.
Environmental responsibility drives the construction approach through committed technical choices throughout the development. The structure comprises 80% timber sourced from sustainably managed forests, certified by both PEFC (Programme for the Endorsement of Forest Certification) and FSC (Forest Stewardship Council). Concrete is used selectively and only where strictly necessary – specifically for foundations, vertical circulation systems, and overall structural stability.
The building's construction methodology showcases innovative sustainable techniques. The façades feature timber frame walls, while floors utilize cross-laminated timber (CLT) technology. Steel beams optimize ceiling heights, creating spacious, light-filled interiors with 2.70-meter ceilings. This construction approach ensures a healthy, comfortable, and efficient working environment for occupants.
Timber's natural properties play a crucial role in the building's performance. As a naturally insulating and moisture-regulating material, timber supports excellent indoor air quality while delivering high levels of both energy and acoustic performance. This creates an optimal working environment that prioritizes occupant well-being and environmental sustainability.
The design philosophy emphasizes a material palette that is subtle, expressive, and sustainable. Spruce wood, used extensively for façades, cladding, and vertical elements, adds warmth and lively texture to the overall aesthetic. Natural anodized aluminum provides an elegant, understated finish for windows, railings, and technical components, while natural zinc completes the palette with subtlety, used for roofing and rainwater downpipes.
At ground level, the architects selected porcelain stoneware and permeable concrete to encourage water infiltration while ensuring material continuity throughout the development. Technical equipment is thoughtfully integrated into the roof design and discreetly concealed, preserving the purity of the overall architectural silhouette. The architecture expresses itself with sensitivity, integrating seamlessly and thoughtfully into its surrounding context.
The project team included several specialized consultants to ensure comprehensive design excellence. Tannacher served as structural engineers, while Fluelec provided both MEP (Mechanical, Electrical, and Plumbing) consulting and energy consulting services. Acoustique Yves Hernot handled acoustic engineering, and Ecr Environnement served as civil engineers. Executive project management was handled by Lamotte and Batitech, with Cabinet Lemonnier providing cost consulting services.
ALTA's Bois Harel Tertiary Complex represents a new way of thinking about office architecture that moves far beyond traditional stereotypes. The architecture steps back to support the site's natural dynamics, reconnect with the surrounding landscape, and meet contemporary demands for comfort, sustainability, and usability. This development embodies a committed, restrained, and human vision of urban development that is resolutely forward-looking, setting new standards for sustainable commercial architecture in France.
