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College "Notre-Dame de Bon secours"

Il Caso Evidenziato 2018 Highlighted Case
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Since the start of All Saints' Day 2017, students in Secondary 5 and 6 of the  College "Notre-Dame de bon secours" in Binche are the first in Belgium to take classes in a building isolated with straw and wooden frame.


A spacious, bright, and healthy pavilion has replaced a prefabricated sheet metal energy wastage. This pavilion is the first prefabricated school building made of wood, compressed straw and clay plaster in French-speaking Belgium. 

Also after much research the management of the college made the choice of a passive construction with materials mainly of plant origin. 


Thus, the construction system of the college which was built by De Graeve in Benelux (specialist in passive constructions); it combines three renewable materials: wood for structural work, straw for walls, earth. In addition, the roof is cork insulated, as the clay coating for the interior lining.


This college uses each subject in a reasoned way to make the most of it and avoids wasting all the grey energies. Building with natural materials made it possible to build buildings with a negative carbon footprint. Being of vegetable origin, the wood and the straw are fixers of CO2. The choice of materials has been designed to promote a supply via sectors as short as possible.


This construction (completed in 2018) is designed to last, the care taken in its implementation offers a long life to the building; in addition, if one decides to dismantle them one day, the materials will be almost completely compostable. 


The interior comfort is also optimized thanks to the absence of volatile substances (VOC) and thanks to the hygrometric regulation properties of the earth coatings. The straw bale walls offer sound insulation qualities.


A special feature is the constructive system that uses straw as insulation and clay plaster for interior lining. Straw construction is still too much considered today as an alternative or even marginal vision of the possibilities of building, but the contracting authority managed to convince.


Energy consumption

  • Primary energy need: 74,00 kWhpe/m2.year
  • Primary energy need for standard building: 125,00 kWhpe/m2.year
  • Final Energy: 125,00 kWhfe/m2.year

Breakdown for energy consumption:  Heating are 37 kWh / m².an


More information: Net energy requirements heating are 37 kWh / m².year instead of 70 to 80 kWh / m².year as standard. (compared to the low energy which is 30 kWh / m².an or the passive which is 15 kWh / m².an). 51 403 kWhep / year are saved between the building situation and the reference value, ie 81.28 kWhep / m².year of savings compared to the reference value.


Envelope performance

  • Envelope U-Value: 0,12 W.m-2.K-1
  • More information:  High performance insulation U = 0.12 W / m2 ° K (passive)
  • Air Tightness Value: 0,51



Heating system: Condensing gas boiler


Hot water system: Gas boiler


Cooling system: No cooling system


Ventilation system: Double flow heat exchanger


Renewable systems: No renewable energy systems


GHG emissions

  • GHG in use: 22,75 KgCO2/m2/year

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