To be modern a tower must be sustainable or appear as such

May 4, a new façade will be mounted on structures reinforced Tower CB 31, ex-tour AXA, future turn First defence. At the top of the building works are underway to transform the tripod designed by architect Pierre Dufau in 1970 in a high tower ten storeys, from 40 to 50, more modern and more slender. Should demolish the obsolete building, rebuild the same, replace it with a completely new tour The two owners AXA Real Estate Investment Management and Beacon Capital have tested several scenarios. "The objective has always been clear to change the perception architectural building, to improve its effectiveness and its urban integration, explains Jean-Frédéric Heinry, General Manager of Cogedim company, master of work delegated to this operation." The increase in surface came only later when studies showed that it was possible. "The renovation brings only 9,000 m2 for a site which the invoice reached 290 million euros of work in addition to 30 million sunk in a longer and more costly than expected asbestos operation. "It is more expensive that the nine, says Jean-Frédéric Heinry." But if it had intended to demolish and rebuild, the site would have lasted twenty-four months. "Two years additional without rent, not to mention the difficulties that would have involved the demolition of a tower from 79,000 m2, built on a slab, impossible to implode as dense as the defence area.

Metamorphosis

The building is changed fundamentally, inner and outer metamorphosis. The original tower consisted of a concrete core which is deployed, as the blades of a propeller, 3 wings of even size. The project designed by Americans Kohn Pedersen Fox (KPF) architects clips one, leaves intact the second and enhances the third. Antenna end this illusion of twisted, 230 metres, or 20 more than the Montparnasse tower. In 1970, the blind Gables were used to shelter the now extremely reduced volume computer cables kilometres. They are now open on their height and naturally shed the plateaus of offices. 18 Metres thickness obtained by the lateral movement of the facades is more standards and patterns of development sought by large companies. This "stretching" to win 200 m2 per floor and offers especially the possibility to move from one wing to another without passing through the core, which was until this impossible. "These new volumes changed the balance of the building by moving its centre of gravity and led us to recalculate the strength of the tower and thicken certain parts of the kernel," explains Pierre Foqué, technical director Iosis Structures, complex studies Office responsible for this renovation. For the rest, Pierre Dufau saw just imagined heights of floors of 3.60 meters that allow today, despite the false floors and suspended ceilings for the "tripaille" of the building, to maintain comfortable volumes.

To be modern, a tower must be sustainable or appear as such. First should be the first high-rise building (IGH) renovated certified HQE defence. While the Tower consumed in its previous version more than 400 kWh / m2 per year, the new should be four times less greedy insulating glazing (double or triple the orientation), the use of various energy sources and the use of solar inputs... The real numbers to verify use and will depend on the behaviour of the tenants.

Scheduled for completion in 2011, First to benefit from the crisis which has slowed, or even frozen, several projects to make the shadow. This tower, the property named, will be the first response to the renewal of defence plan launched in July 2006 which proposed additional rights to build the owners willing to invest in the modernization of their buildings. If AXA and the Group Beacon are sentence now predict the value of the tertiary rents in 2011, they can build on the dynamics of the business district and the advantage of having fired the first.