First energy-positive archives building in France
The Nord Departmental Archives'Cube' will be home to some real treasures - 80 kilometres of historical documents for starters. However there is also a level of inventiveness in the design, making this the first energy-positive archives building in France. This giant structure will in fact consume less energy than it produces.
Draconian temperature and humidity requirements
When the work is finished, a metal mesh will enclose the seven-storey monolith built over 14,000 m2. It will be a purely aesthetic covering because the building is designed to provide optimum conditions for conservation. The interior temperature of the store rooms may only fluctuate by 0.5°C per day(2°C per week) and relative humidity by 1% per day (5% per week).
François-YvesLelong, Deputy Director of Norpac's Fluids Division, says that these constraints led the team to find new solutions: "To make a structure as dry as possible and reduce water ingress, we pre-fabricated units on another site. To condition air inside the building, instead of conventional air handling and cooling units, which consume large amounts of electricity, we opted for a desiccation technique using an absorbent material: silica gel."
The annual energy balance is positive
What's more, this highly efficient building will not work out more expensive for the Nord Department since it will produce more energy than it consumes. This characteristic, currently unique in France for public buildings, results fromusing three parallel approaches.
The first relates to work on the performance of the building envelope.
Energy requirements are limited and summer and winter building comfort are provided by enhanced airtight sealing, through the installation of 21 cm thick exterior insulation and triple glazing. The other two approaches relate to installing energy-efficient equipment and independent electricity production. François-Yves Lelong explains these technical choices. "Heat and part of the electricity supply are produced using avegetable oil co-generator. 350 m2 of photovoltaic panels on the roof cover the remaining electricity requirement, which we have been careful to limit by using lighting which is controlled according to building occupation".
Delivery : end of 2012
Delivery of the new Departmental Archives for the Nord is planned for the end of 2012. After this will follow a period of six months to relocate the archives, dismantle the old depository and finish the surroundings. Land registry deeds, census reportsand historical documents will then be able to peacefully continue their growth at a rate of one kilometre per year in their new home.
3 questions to Eric Conratte, Site Director of the Nord Departmental Archives Project
What are the special features of this operation?
Eric Conratte: We have encountered relatively unusual constraints during the execution phase. For example, we have had to seal off the entire surrounding infrastructure, as far as the solid pile heads, including the lift shaft pit. Creating a completely airtight building demands extreme vigilance regarding the quality of execution, in order to minimise thermal bridges and heat loss.
What new solutions have you implemented?
E.C: We have commissioned the services of a thermal engineering consultancy that is helping us make the right choices when we see a difference between our calculations, which aim for perfection, and the reality of the execution.
Once this building is operational, what willyou be particularly proud of?
E.C: Aboveall I will be satisfied to have found the means of hanging 4,200 m2 of facade surface coverings, which we currently expect to be perforated by 120,000 to 160,000 fastening holes, whilst also maintaining airtightness of the building!
Architect's view
"This achievement has brought about new approaches both in architecture and construction.It is impossible to act on reflex here. This project is bringing together more brainpower than most"
Pierre Gilbert,
Architect at ZigZag.
Publication : December 2011.
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