Published on 13 February 2026
Pascal Chereau, constructor director / design build division, and Nahel Zine-Eddine, assistant site manager (apprentice)
BEG Ingénierie is delivering a 14,000 sqm, five-storey office building for a defense industry client. This complex project, executed on an occupied site, combines high technical requirements, architectural rigor and environmental performance.
A joint interview with Pascal, who is retiring after 35 years with BEG, and Nahel, an apprentice site manager…
What are the main challenges of working on an occupied site?
PC: The primary challenge is safety. We are operating on a sensitive site where part of the client’s activities continues throughout the works. This requires millimetric coordination, controlled access points and strictly segregated construction zones. Every stage of the project must be anticipated, validated and secured. We must also mitigate noise impact and carefully manage flows and day-to-day coexistence.
NZE: As an apprentice, this project has been extremely instructive. I quickly understood that when a construction site is not operating in isolation, nothing can be left to chance. The immediate environment influences everything: organization, scheduling and construction methods.
Does constructing a multi-storey building create additional constraints?
NZE: The project is executed level by level, block by block. Technical trades are layered and cannot all operate simultaneously. We must coordinate highly technical interventions in sometimes confined areas. Managing priorities, trade interfaces and circulation flows is essential.
PC: The building’s geometry adds another layer of complexity. But it is precisely in this type of context that BEG’s added value becomes evident. We anticipated a long and highly structured preparation phase, with six months of upstream technical coordination to design and integrate all networks within a constrained space. Every detail had to be considered. This allows us today to move forward confidently while integrating necessary adjustments. Our objective is to deliver a technically flawless building where every piece of equipment fits seamlessly.
The building demonstrates strong architectural ambition. How does this translate into your daily work?
PC: The architect designed an elegant building, with high standards in terms of materials, natural light and finishes. This demands rigor at every level, right down to site management practices. Our client is highly attentive to architectural quality, not just functionality. They also value the discipline and organization maintained on site.
NZE: The building is designed to be in harmony with its surroundings. Particular care has been given to the external areas: landscaped zones, terraces and the building’s immediate environment. It is not simply a workplace; it is an environment conceived for its users. Each floor is connected by footbridges, and circulation has been designed to serve shared spaces efficiently.
What energy and environmental choices have been made?
NZE: The building will be fully energy self-sufficient. Two heat pumps will produce both heating and cooling. Heat recovery is planned to supply a future neighboring building. In addition, 585 sqm of photovoltaic panels complete the system. The building is surrounded by woodland, and greenery has also been incorporated within the building perimeter through a landscaped patio.
PC: We adopted a comprehensive sustainability approach. The building envelope has been carefully designed, with particular attention to external thermal insulation materials and acoustic performance. The building’s orientation and geometry maximize natural daylight. This is a demanding project, both in design and execution. With a view to obtaining environmental certification, we closely monitor every detail, even during the construction phase, from waste management to water consumption.
Is it challenging to work for a defense industry client?
PC: Expectations are high, but the team is strong and the building will meet the client’s standards. I did not perceive greater difficulty as such. There are naturally enhanced security procedures for site access, and we must anticipate all identity checks. We developed a comprehensive induction handbook; contractors are informed of all constraints from the outset. It is a practice I have adopted for other types of clients as well.
