This large renovation project at Rue Myrha, in Paris’s 18th arrondissement, gave birth to an innovative building – the first social housing project of its kind – which combines a metal framework with hempcrete.

The weight factor

Tradical^® Hempcrete is an ultralight concrete weighing in at 330 kg/m³ compared with 2.23 t/m³ for reinforced concrete.

This was a huge advantage for the Paris site as it enabled the NORTH BY NORTHWEST architects and the LM INGENIEUR design engineers to reduce the foundation footprint to a depth of 3 m, with injections to a depth of 40 m.

A low impact on the environment

The project’s carbon footprint was also very good, as the impact of the construction stage was reduced by 60% with regard to Paris’s climate plan expectations, and it only represents a quarter of the overall carbon footprint (use and construction) over 40 years compared with a standard construction method.

• Performance of the envelope: French H&E profil A certified
• GHG emission: 5kg CO₂e/m²/year
• Energy performance: 49kWhPe/m²/year

Façade insulation

Thickness = 27 cm, R = 3.17 m².K/W, lambda = 0.085 W/m.k

Roof insulation

Thickness = 27 cm, R = 4.5 m².K/W, lambda = 0.06 W/m.k

• Floor area of the building: 570 m² of net floor area (SHON)
• Total floor area of apartments: 345.78 m²
• Height of the building: Ground floor + 5 floors (with setback)
• Depth of foundations: 3 m
• Injection to a depth of 40 m
• Solar hot water
• Rainwater harvesting
• Natural self-insulating system
  • 150 m³ hempcrete
  • Tradical^® PF70 lime and Chanvribat^®

BCB Tradical^®: contact@weber-tradical.com

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A thermal performance of 45 kWhPE/m²/year comfortably met the requirements of Paris’s climate plan. The building consists of a main load-bearing structure made of reinforced concrete and a secondary timber frame structure. Both structures are covered in Tradical^® Hempcrete, which makes up the infill and the in-built thermal insulation.
This homogeneous envelope benefits from everything the lime-hemp composite has to offer – moisture transfer, summer and winter thermal comfort and thermal inertia – with a very light carbon footprint to boot.
A series of thermal performance measurements for the building under real-life conditions will be taken to confirm the initial studies conducted for the project.
The behaviour of users will also be monitored to understand how facilities are actually used.
In the long term, the results will enable the efficiency of the building to be optimised and they will also be useful on future projects.

Technical choices made
Mixed load-bearing structure
– main structure built with reinforced concrete
– secondary structure built out of timber

Type of work undertaken
Construction of an apartment building with four floors, housing four studio apartments, two four-room apartments and two five-room duplex apartments.

Performance objectives
Bâtiment Basse Consommation (French energy-efficient building certification)

Apartment building on Rue Bourgon in Paris – Summary of the characteristics

Contracting authority
• Paris Habitat

Design
• Atelier D “Sustainable Architecture and Development” 66, avenue des Champs-Elysées
75008 Paris – www.atelier-d.fr

Technical follow-up
• Structural engineering consultants: SERF – 95600 Eaubonne
• Technical and thermal engineering consultants: INGELEC and TBS – 94100 St Maur des Fossés

BCB Tradical^®: contact@weber-tradical.com

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Preserving the identity of the location

This project included ten residences of varying sizes, each with a private garden. The challenge of the project was to ‘adapt an old rural building to contemporary uses.’

The long house, a traditional building in the Ile-de-France region, was reincarnated for the modern-day world. The apartments are traversing and have floor-to-ceiling windows for extra light. The irregularly positioned openings in the façades allude to the modifications made over time to the initial design of the buildings – and keep a farm-like spirit too!

A reproducible system

The building system was rationalised and led to the design of a template for creating modules of 5 to 7 m in length and 2.7 m in height. This semi-prefabricated system had several advantages: the lightweight structures were easy to lift and transport, easy to store on site and quick to assemble.

• Performance of the envelope: equivalent to a new BBC (low-energy house)
• GHG emission: 5 kg CO₂e/m²/year
• Energy performance: 50 kWhPe/m²/year
• Design highlights
  • Solar hot water
  • Masonry stove
  • Natural ventilation

Natural self-insulating system

552 m³ of hempcrete made with Tradical^® PF 70 and Chanvribat^®

Tradical^® Hempcrete insulating wall: surface area of 900 m²

Thickness = 28 cm, R = 3.3 m².K/W, lambda = 0.085 W/m.k

Tradical^® Hempcrete insulating roof: surface area of 1,000 m²

Thickness = 30 cm, R = 5 m².K/W, lambda = 0.06 W/m.k

BCB Tradical^®: contact@weber-tradical.com

More examples about hempcrete homes and buildings