Case Study: nZEC - New construction of 34 dwellings in the residence Jean Jaurès in Décines-Charpieu, France

Short Description

The energy management strategy was an important aspect of the project with:

- The setup of an environmental supervising committee
- The use of bill of specifications including environmental prescriptions
- The participation of architects experienced in environmental design
- The use of dynamic thermal simulation software
- The involvement of the architects in the execution works and the scheduling, leading and coordinating phases to avoid a division of the project management.

At the beginning of the project, the label THPE (Very high energy performance) was aimed at. This label considers a level of consumption lower than 20% of the baseline consumption defined by the 2005 thermal regulation (this baseline consumption corresponds to the consumption of the building including imposed performances of the equipment and the structure).

Finally the objectives evolved and it was finally the BBC label (Low Energy Buildings) which was aimed at. This label considers a level of consumption lower than 50 kWh/m²/year (for heating, cooling, DHW, ventilation and lighting).

The Qualitel label (Habitat&Environnement by Cerqual and the QEB label for the management of the project respecting the environmental quality of buildings were also obtained.

Key Elements

Water Saving

Water savings equipment are used as well as low-energy bulbs, low-delaying sensors and the priority given to natural lighting in the common parts.

Thermal Insulation

One of the important aspects of this project is the external insulation fixed on a reinforced concrete structure. Above this external insulation, on the west and south façades, double skin façades were set to act as sun breakers. Self-supporting balconies were installed to avoid thermal bridges. Lastly, to ensure a high performance of the building, highly performing windows were selected.

Certification

The following certificates were obtained for this project:

BBC effinergie: Certificate obtained for consumptions of primary energy lower than 50kWh/m² year for heating, adjusted according to the climatic conditions and altitude.

Qualitel Habitat&Environnement by Cerqual: This certificate is related to the compliance with some commitments:

• Energy performances
• Water and Electricity savings
• Environmental management of the project
• Cleaned building site
• Choice of materials

QEB: Management of the project respecting the environmental quality of buildings.

Funding

Ventilation

In terms of ventilation, it was chosen to install a mechanical ventilation with heat recovery.

Solar Thermal

A solar domestic hot water system was installed on the roof. The remaining needs in terms of domestic hot water as well as the heating needs are ensured by a condensing boiler.

Environmental Design

The summer comfort was addressed through:

• Double skin façades on the west and south façades acting as sun breakers;
• The use of a mechanical ventilation with heat recovery;
• The high inertia of the building (reinforced concrete structure).
  
  
  

Main Results

• The energy management of the project was a key point and enabled to consider the energy-related aspects very early and all through the project.
• In terms of structure and systems, the choices were directed towards a better performance of the building: condensing boiler, solar panels, external insulation, ventilation with heat recovery and use of water and energy savings equipment.
• In terms of consumptions, the comparison between the calculated and the real consumptions is the following one.
• Calculated consumptions 49.8 kWh primary energy/m²/year (composed of Heating: 10.2 / DHW: 17 / Lighting: 7.34 / Ventilation and other usages: 15.2)
• Real consumptions (estimated from the 136 first days of  operating of the residence): Heating: 10 / DHW: 16
  
  
  

Lessons learned

• Among the strong points of the project, it has to be underlined that the calculated consumptions correspond to the real consumptions. Concerning technical features, the summer comfort was carefully addressed and the use of water and energy savings equipment among other solutions selected enabled to reach the expected performance level. The energy management strategy was one of the key factors for the achievement of these performances.
• Concerning the weak points, it appeared that the behaviour of the tenants was not modified, they did not adapt to the requirements of the BBC level of the building. The support of the tenants was insufficient and should have been addressed more carefully.
• The process (energy management strategy, involvement of the architects in the execution works…) also requires a high number of actors and can be time consuming. Another weak point is the maintenance of the ventilation system which can be problematic (inexperience for the evaluation of the maintenance company, time-consuming because requires to enter in the dwellings). The solar installation can also be difficult to manage due to the inexperience and the high number of actors involved.
  
  
  

Additional Information

Ms Carine Puyol
USH - The French Federation of Social Housing Providers
E-mail: carine.puyol@union-habitat.org
Web: www.union-habitat.org