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Green box on the roof: an example of office extension in Lyon

Wyróżniony Przypadek Highlighted Case
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Photo credit : state-of-places-studioericksaillet. Other Marc campesi photos

The scope of the project was to increase the office surface through a roof extension, having a surface of around 900 m2, following sustainability and energy efficiency criteria.


One key aspect of the project was the reduced life-cycle impact of the materials that were chosen from local producers and with a reduced carbon print. In particular, the main structures are made of wood coming from Rhône Alpes region and insulated with a bio fiber matial produced in France and composed by hemp, linen and cotton. The insulation thickness is around 15 cm leading to a thermal transmittance of 0.22 W/(m2 K). Moreover, the acoustic insulation and the flooring outdoor deck are made of recyclable materials that are also made in France. The ceiling, also supported by a wooden structure, presents a steam brake and it is insulated with 20 cm of bio fiber materials and reinforced with 10 cm of rigid polyurethane.


The structure is a prefabricated and pre-assembled within an off-site manufacturing process of six months that allowing to reduce the construction and installation time, minimizing inconveniences for the occupants of the existing building.


The heating is supplied by a heat pump with a COP of 4 that does not need the use of an electric back-up down to -20 °C., while the cooling is made by a variant refrigerant volume system. Both heating and cooling are coupled with dual flow ventilation with heat recovery, that allows for a great flexibility and efficiency of the system. Moreover, the system is designed to reduce the impact of the distribution and emission systems, that are included in the ceilings, and allows for a significant flexibility of the office spaces.


The final energy need of the building is 48 kWh/m2 year, with a breakdown of 12 kWh/(m2 year) for heating, 18 kWh/(m2 year) cooling, 17 kWh/(m2 year) lighting, and the rest for auxiliary systems.


If you want to read more information about the building and to access to the videos of the structure installation, visit the project page!

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