The act2 demonstration activities in Nantes are focused on the Île de Nantes district, an area of 340 ha. A total floor area of 80,000 m² of new buildings with advanced energy standards (housing + offices) has been constructed. A large number of these buildings is connected to district heating from waste incineration. Specific decentralized renewable energy systems complete the performed measures, like an energy efficient air-to-water heat pump at the “L’Ile Rouge”, a tertiary building of 3,069 m² and a wood-chip boiler of 72 kW.
Among the building projects there are two large sites: “Tripode” (Picture 1) with 20,000 m² tertiary and 10,860 m² housing projects, connected to the waste-to-energy district heating system, and “Terrain des Gendarmes” - a 16,393 m² housing project, composed of 4 plots connected to the waste-to-energy district heating system and a 77 m² solar installation (covering part of the DHW demand). At the “Tripode” building also an absorption chiller of 258 kW has been installed.
Social housing projects like a social residence for young workers (1,810 m²) and “Corto” (2,800 m²) are included in the demonstration activities as well as the “Prairie au Duc” School (3,700 m²). A Wood Center (tertiary building of 1,500 m², Picture 2) has been built and is dedicated to the promotion of wood as construction material and source of energy.
The “Fonderies” Headquarters Building (4,248 m²) and the large-scale PV installation (182 kWpeak) at “Beaulieu” Shopping Center are explained in the “More Detailed” section.
Beaulieu PV Power Plant
The Beaulieu PV power plant (Picture 3) is implemented downtown, on the top of the car park, which was erected within the renovation-extension of the Beaulieu shopping center. This 1,450 m² installation made of polycrystalline panels is to be realized within an innovative legal arrangement, which specifies the conditions for installing the PV power plant under Nantes Métropole's ownership on a private domain (the shopping center).
It is also aimed at raising public awareness thanks to this highlight project. Actually 2 totems display the electric output and the CO2 emissions saved to the 120,000 people who visit the shopping centre every week.

Table 1 - Facts and Figures about the PV plant „Beaulieu”
The 'Fonderies' Building
This building reaches the highest energy standard in France: ‘Bâtiment Basse Consommation' (Low Consumption Building). Being a tertiary building its energy consumption accounts for less than 50% of the regulatory energy consumption.
To reach this energy standard the building envelope (Picture 4) has been constructed with high insulation level: 20 cm external insulation (rockwool) on façades, 15 cm (rockwool) for roof, 12 cm PSE (expanded polystyrene) for the basement and Low-E double glazing filled with Argon for the windows.
Different natural (passive) measures have been applied to keep the indoor climate on a comfortable level. External sun baffles with horizontal (east) and vertical (west) moveable louvers reduce the solar irradiation, a forced nocturnal ventilation cools down the building naturally and finally an internal garden (Picture 5) serves as a thermal regulator.
The heating energy for this building is provided by a waste-to-energy district heating system, a double-flow mechanical ventilation with heat recovery extract heating energy from the exhaust air.
Developer
La Nantaise d'Habitations and CIL Atlantique
Architect
Alter Smith Agency
Energy Engineering
AREA
Commissioned
July 2008
Gross Floor Area
4,248 m²
Concerto grant
57,985.20 €
Total primary energy consumption
57 kWh/m².a
- heat: 6.5
- ventilation: 18
- lighting: 32
- auxiliaries: 0.5
Table 2 – Facts and Figures about the “Fonderies” building