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Rehabilitation
of the First Tower in Paris-La Défense

(France)

It was a determination to give Paris a modern and spacious business district that led to the
creation of La Défense in the 1960s. The First Tower, known at the time as the UAP or Assur
tower, was part of the second wave of construction that took place in the district. Naturally, by
We have been working in the the early 2000s these early generations of towers were becoming obsolete. Refurbishment
La Défense business district programmes were therefore launched, including one for the First Tower.
for many years and today we
are still carrying out different The aims were multiple. The building had to be completely reconfigured to gain more usable
assignments for most of the space, but it also had to be adapted to new safety and energy consumption standards. Modern
major property development catering and reception facilities had to be provided and greater user comfort was needed in
projects being implemented general. The tower also had to be connected more effectively with its urban environment and
there. In 1974, we supervised local transport, shops and housing. The original building, constructed on a foundation slab, had
the construction of one of the not really taken such considerations into account. Several firms bid for the project, but it was
very first high-rise buildings in finally KPF and SRA architects that were successful. Their proposal was particularly unusual
the district. 35 years later we and ambitious.
took charge of its refurbishment The original 3-branch radiating structure was redesigned to make the tower’s geometry
– a phenomenal task. more striking. Each wing was to have a different height. One was slightly lowered, the second
raised by a few storeys and the third by 12 extra floors! At the same time the structure of
the central connecting core was optimised and the façades pushed out as far as the external
columns, resulting in a huge increase of 10% in usable floor area. The outer envelope was also
redesigned to provide as much natural light as possible while taking thermal requirements into
account. In this way, the tower obtained French HQE green building certification.
Very few towers in France or Europe have undergone such a thorough overhaul modifying their
structure to this extent. 7000 extra tonnes were added, the equivalent of the Eiffel Tower, and
the building’s centre of gravity was modified.

Olivier Deloof
Deputy Director, Regions | Buildings, French Regions & Equipment

96 I ARTELIA, 10 YEARS OF EXISTENCE, 100 YEARS OF EXPERIENCE ARTELIA, 10 YEARS OF EXISTENCE, 100 YEARS OF EXPERIENCE I 97