ALTA Architectes – Urbanistes has completed an ambitious office project on Chemin du Bois Harel, a road that marks the boundary between Rennes, an industrial city in north-western France, and the neighbouring municipality of Saint-Jacques-de-la-Lande.
The Harel Wooden Office Complex (Bois Harel Tertiary Complex) takes a measured approach to office architecture, shaped by the dynamics of the site and its relationship to the surrounding landscape. The project responds to contemporary expectations of comfort, sustainability, and usability, offering a restrained yet forward-looking vision of urban development that prioritises well-being and respects the natural environment.
Bridging countryside and city
The project’s site was once given over to market gardening, most visibly through the Crublé greenhouses — operated by a local horticultural family until their closure in 2004. Today, this transitional territory is being redefined as a threshold between the countryside and the city.
To the west lies a rural landscape of open fields and scattered housing; to the east, the Rennes ring road with a constant flow of traffic. Positioned between these two contrasting realities, the site offers fertile ground for rethinking urbanity. Here, ALTA has designed a connecting architecture, both simple and contemporary, bridging the scale of everyday life with that of the wider landscape, while safeguarding quality of life.
Building layout
The Harel Wooden Office Complex is organised around two rectangular three-storey buildings (A and B), each with a shared underground basement that houses parking. Designed in accordance with France’s 5th category ERP regulations, the project incorporates 170 parking spaces — several equipped with electric vehicle charging points — alongside secure bicycle storage facilities that encourage active mobility. (ERP stands for Établissement Recevant du Public — literally “establishments open to the public.” A 5th category ERP refers to modest-capacity public buildings that are subject to adapted fire safety and accessibility standards.)
Building A East Facade
Building B West Facade
Sustainable construction
The construction adopts an environmentally responsible approach, underpinned by carefully considered technical choices. The largely timber complex is built with wood sourced from sustainably managed forests, certified PEFC and FSC, while concrete is used only where necessary — for example, in foundations, vertical circulation, and structural stability. Reinforced concrete foundations and ground floor slabs provide a durable base for the cross-laminated timber (CLT) superstructure.
Timber-framed facades are finished with spruce cladding in a false open-joint rhythm — milled to resemble evenly spaced slats while remaining fully closed — articulated by projecting fins and paired with aluminium-framed glazing. Technical floors and demountable ceilings allow services to be discreetly integrated and easily maintained, supporting the building’s flexible office layouts. Bright and spacious, the offices achieve a 2.7-metre floor-to-ceiling height. Building services equipment is integrated into the roof and discreetly concealed, preserving the purity of the silhouette. At roof level, natural zinc standing-seam coverings, aluminium copings, and glazed railings define the terraces, while adjustable slab decking creates usable outdoor space.
Together, these elements present a balance of robustness and warmth, marrying concrete’s solidity with the lightness and sustainability of engineered timber. This construction approach fosters a healthy, comfortable, and efficient working environment: timber, with its natural insulating and moisture-regulating properties, helps maintain excellent indoor air quality while ensuring strong energy performance and effective acoustic control.
Material palette
The design is grounded in durable materials, carefully selected for their appropriateness and their ability to engage with the surrounding landscape. Spruce, used for facades, cladding, and vertical elements, adds warmth and texture. Natural anodised aluminium brings an understated elegance to windows, railings, and technical components, while natural zinc — employed for roofing and rainwater downpipes — completes the composition with quiet refinement. At ground level, porcelain stoneware and permeable concrete encourage water infiltration while ensuring continuity with the building fabric.
The architecture is expressed with sensitivity, integrating seamlessly into its context through this subtle, expressive, and sustainable material palette.
