A calculation in the medium term brings added value

The Gesec, a group of economic interest of the sector health and climate, just escape the puzzle of sustainable development: how to enlarge its premises and better heat while spending less, all without investing in new This set of 300 companies in the heating, cooling or plumbing, which weigh more than 1 billion euros of turnover, is to build a new headquarters in a building built in 1987 and left free by the former Regional Directorate Centre-West of Peugeot, in Saint-Avertin, near Tours (Indre-et-Loire). The price of the 1,000 square metre renovated returned to 700,000 euros.

In addition to his Finnish FIR siding, which acts as insulation from outside, this parallelepiped has the merit to meet the ambitious specifications of the Grenelle of the environment. Class D, the most energy-intensive, ongoing at the time of cheap oil, moved to class A, the more efficient. In this case, the regulations will require 50 energy savings to the public as soon as 2010 buildings and private in 2012, in order to achieve the standard BBC (building low consumption). The Gesec goes further by dividing the energy consumption of the building by four: 47.7 kilowatt-hours per square metre, against 211 kilowatt-hours per square metre previously.

If the most spectacular aspect is housed on the South façade, with 36 square metres of photovoltaic panels to sell electricity to EDF, the technical interest lies elsewhere. "We visited the almost airtight building," describes Pauline Mispoulet, Director of the Gesec. Glazing has been overweight, insulated ceilings are lower. The air is renewed by a ventilation double flow which regulates interior temperature with the inertia of the building. "Stop to ventilate the offices with the cold air the winter for example, says Pauline Mispoulet.". Exhaust air heat warms the air from outside, and therefore we spend less heating. "Everything has a price: climate engineering amounts to 250,000 euros, it is the most important expenses. In addition, the computer server of this structure of 22 employees supplies calories a heat pump.

700 euros per square metre

"Nothing is revolutionary, all techniques are known," analysis Richard Coignard, LBE fluid pattern, a consulting company in control of work in the energy field. "The primary demonstration of this eco-renovation, it is an investment limited to 700 euros per square metre." For the nine known to do. "For the former, which represents 98 of the buildings, it is a huge challenge," continues this interested engineer for future rehabilitation of hospitals, schools and all other buildings of post-war termed "energy wreck", because they let escape calories and consume a lot of energy.

The trick lies in the financial package, precisely where the shoe pinches for most of the buildings which are the high environmental quality. The 700,000 euros were borrowed from Credit Agricole over seven years. The lease was negotiated with the owner, the Nantes land west Pierre investment. It agreed to reduce by 20 rent, and lease of nine priority of renewal to the Gesec, so that it gets a return on investment. "Our owner is less but longer and has a building ahead of the future 2010 thermal regulation standards: it is the best calculation for everyone", summarizes Pauline Mispoulet, which concludes: "A company which leases its premises must not deprive hiring standards release work." A calculation in the medium term brings added value.

This example shows that the environmental constraints are not out of reach. Which opens up prospects for any tertiary housing built since the second world war.