Manehome: a unique 22.400 m² site to bring together 180 Enedis agents in Blois

The location, at Chaussée Saint-Victor near Cap Ciné, was chosen for its potential in terms of space (22 m²) and proximity to the A400 motorway. It is clearly the choice of efficiency and optimization that was made, a choice that covers all the key points of this project.

Bringing together industrial and tertiary activities

The site was designed in an arc, to hide the interior, the courtyard and the equipment.
The mix of activities is reflected in the very concept of the building: a concrete structure for offices and public reception, associated with a metal framework for the technical rooms. A concept created by Apside Architecture, which combines aesthetic and functional dimensions, and which put the site's project management firm, Manehome, in the face of major technical challenges.

3 major technical challenges to overcome

If the project manager has an important role of coordinating the teams and organizing the site, he has a delicate upstream mission: to provide technical solutions that will allow the architectural concept to materialize.

The “signature” of this building: a 13 m high facade in exposed concrete

The main entrance opens onto a huge gray concrete wall, raw and refined. This type of finish requires an innovative technical solution, the betomur for a perfect result. Those are
prefabricated concrete walls with integrated insulation which makes them ultra-efficient
meeting the requirements of RT 2012 and anticipating future regulations of the
RT 2020. Anticorrosion and airtight, the wall is also suitable for any zone of seismicity 1 to 5.

The various elements, manufactured off-site, are assembled on-site. The pouring of concrete consolidates the whole. An assembly that requires careful handling of the different modules, but allows a significant saving of time on the site and to be less
weather-dependent. These elements, prefabricated in the Paris region by SORIBA,
are in fact produced indoors, in optimal working conditions.

Each element is composed of two prefabricated concrete walls serving as formwork, an insulating wall providing thermal insulation from the outside and a central void allowing the pouring of a concrete core while greatly limiting thermal losses.

Bring together the concrete structure and the metal frame structure

Different solutions for joining concrete and metal structures have been studied in
upstream to ensure the junction between its two materials. It is a real
dilemma: the evolution over time of the two types of materials is very different, which does not allow them to be linked. However, the seal must be perfect.

Ensuring the junction between the clad metal framework and the betomurs must therefore be carried out with the greatest rigor in order to ensure the caulking between the various zones.

To optimize this junction, design offices and intervening companies worked together and chose to put the two structures on hold to coordinate and complete them simultaneously, and not one before the other. Finishing one before the other could have created thermal bridges and leaks.

To make this type of decision and coordinate the stakeholders, you need a real collective spirit on the site, a common quality requirement and a good conductor. This is the mission of the project manager, Manehome, a firm created by Anthony Conte in 2014 which takes up this type of challenge on a daily basis: optimizing technical solutions, coordinating workers on the sites and ensuring real monitoring in the field.

Modular arrangement of partitions with a high level of acoustic treatment

The building is made with a high level of sound insulation, rarely put
implemented in tertiary premises. This required a complex preliminary study.
The challenge this time is to combine a high level of sound insulation, with movable glass partitions that allow the office and meeting spaces to be completely redistributed if necessary, and the electrical and IT networks that pass through false ceilings and false floor.

There is no pre-existing case to refer to. The solution was therefore first calculated theoretically, then implemented and tested in a control room. The acoustic tests validated the technical solution which was then deployed over the 3 m² of the tertiary part.

Promote local employment, French materials and equipment

Enedis does not intend to own its premises. It is therefore a private investor who owns it and has delegated the construction to the developer Essor. Essor entrusted part of the project management to Manehome, who oversaw the site and coordinated the workers. Particular vigilance has been brought to the choice of service providers, both for the work and for the equipment and materials. On the quality / price ratio of their service, but also on their proximity. In a responsible logic, the speakers were local companies, from Blois or the surrounding area, except for two very specific services (false floor and roofing frame). The materials and equipment made in France have been favored. More than a hundred people worked on this site for a year and a half, bringing great momentum to local employment and related jobs.

Project management in an uncertain universe

The contrast is always striking between the rigor that a team must show
project management on a project of this size and the diversity of the risks that will
come and disrupt the site. Despite a methodical and precise organization, the project manager has to constantly adapt to external circumstances.
unexpected. A profession which requires steel nerves, especially in 2020. Thus this site has, in turn: interrupted by a shell discovered on site and which had to be defused; upset by an accident that
injured four people with immediate stoppage of work for safety reasons and then reorganization;
slows down by inclement weather; and finally blocked by the containment of March-April 2020.

The health crisis required a total reinvention of the organization of work on site

Manehome was able to resume work at the end of April, by completely reorganizing the
interventions and planning.

Compliance with barrier gestures limited the number of simultaneous workers on the site. To optimize a new organization in a completely new context, it was necessary:

- know the specificities of each person's business in order to offer an agile organization
and efficient,
- know how to combine the requirements of the client and the multiple constraints of
construction,
- know how to speak the language of the customer and that of the building, to be the bridge between these two
universe and maintain the site within a reasonable time without compromising on the quality of
production.

“Faced with the Covid crisis, it has been helpful to have local workers. Planning is at the heart of their business and everything had to be rethought. This led them to take more responsibilities and initiatives, in relay with us who had limited mobility due to travel restrictions. Trust was paramount. ” Benoit Leroux, Works Director of Project Management, Essor group