A positive energy R+3 commercial building in Saint-Herblain (44)

"Delta Green", a mixed wood/concrete tertiary building of 4 m600 on R+2, is being built in Saint-Herbain (3), near Nantes, for delivery scheduled for early 44. The design of this program, led by the developer GALEO, focuses on energy performance and energy autonomy to obtain Passivhaus certification.

A COMMERCIAL BUILDING AIMED AT PASSIVHAUS
Delta Green was born from the observation that today's buildings, theoretically efficient and in accordance with current regulations, are energy-intensive, without any real control over consumption. The goal was to create an office building designed to be innovative and energy-autonomous, capable of producing and storing its own energy while taking into account its uses.
Delta Green, a private building located in Ar-Mor Park in Saint-Herblain and intended for sale or rental, is seeking Passivhaus certification. This German label is awarded to buildings with very low energy consumption.

Optimizing natural resources from the design stage
The architecture of this building was designed to make the most of natural resources: natural light, solar gain, solar protection in summer... Equipped with quality envelope insulation, the building benefits from optimal facade equipment and orientation. The glazed facades, facing south and north, are equipped with fixed and adjustable vertical sunshades providing the necessary solar protection according to needs. The east and west gables, integrating the staircases, are glazed to provide natural light and sufficient for their uses. The concrete gables that provide the bracing are clad with wood cladding.

A building adapted to changing uses
Delta Green benefits from layouts and construction systems adapted to accommodate users and their needs. The flexibility of the building's spaces and uses is reflected in the implementation of open floors, via a "no walls, no posts" system, to facilitate accessibility and interior layout. Secondary spaces—restrooms, archives, technical rooms, elevators—that do not require natural light, are arranged in the center of the open floors to facilitate user access.

LCA'S EXPERTISE APPLIED TO DELTA GREEN
LCA - Les Charpentiers de l'Atlantique -, with its expertise in timber construction with workshop prefabrication, was selected to contribute to the realization of this project. This collaborative project brings together a dozen regional partners, including the EMC2 competitiveness cluster, Polytech Nantes, Icam, the IUT of Nantes-Saint-Nazaire, the School of Design, and the Ecole supérieure du bois.

LCA works on prefabrication in the workshop
LCA - Les Charpentiers de l'Atlantique - worked on the project for a period of six months, supervised and managed by around ten people. Specializing in workshop prefabrication, the company applied its prefabrication skills to the creation of closed and curved walls. For this project, LCA carried out:
• exterior insulation,
• the installation of closed and curved walls, manufactured in advance, added to the facade,
• wooden decking,
• openwork wood cladding, metal and compact underside,
• airtightness of the sills*,
• the installation of wooden consoles covered in zinc.

The complexity of the project lies in the construction of suspended walls with low thicknesses of concrete and metal while respecting the technical constraints and airtightness of the project. 

*part of the wall, interior or exterior, located between the floor and the window sill

Wood, a key element of construction for LCA
The construction of this three-story building combines concrete and wood. Selected for the insulation and façade walls, wood—a natural, sustainable resource with excellent physical properties and quick to install—contributes to the quality of life for users within the spaces.
The architects dimensioned the wooden elements allowing for prefabrication of walls and other structures, in order to facilitate transport and handling.
Two types of wood highlight this project. The project architects and LCA - Les Charpentiers de l'Atlantique - opted for Class 2 pine/spruce for indoor use, a species particularly suited to "damp" and unheated rooms. Natural Douglas fir was used for outdoor use.

Site information
Geographic location: Saint-Herblain (44)
Type of site: construction of a mixed wood/concrete R+3 commercial building
Surface area: 4m²
Project owner: GALEO
Project manager: Delta Engineering
Architect: CR&ON
Structural design office: SERBA
Timber construction company: LCA - The Atlantic Carpenters
Total cost of the project: €8
Amount of the LCA project: €547
Overall construction time: 13 months
LCA construction timeframe: 6 months
Construction site delivery: early 2017

More info - Biom Work approach
In a rapidly changing context, the company LCA - Les Charpentiers de l'Atlantique - works daily with its partners to support employment and quality of life in its area of operation.
LCA commissioned Biom Work, an independent rating agency.

LCA's social performance was rated "Excellent" with 51% of its activity being redistributed to employment, public services and the environment.