The Commission is in the process of updating some of the content on this website in light of the withdrawal of the United Kingdom from the European Union. If the site contains content that does not yet reflect the withdrawal of the United Kingdom, it is unintentional and will be addressed.

Building a new organic supermarket: Luxembourg

Wyróżniony Przypadek October 2015
Share this Post:

Main entrance of the supermarket

A new type of shop has been developed on an organic farm which aims to increase customer satisfaction by offering a comprehensive range of sustainable products in a healthy and sustainable building. The new building is a timber-frame construction. The building has a flat roof which has incorporated a green roof on top. This green roof is intensively farmed as it is the garden for the passive house. The passive house also forms part of the total surface area and is on the 1st and 2nd floors. Both buildings are connected to the existing building which is comprised of a restaurant and several residential units.

The supermarket was built using a waterproof concrete floor slab which is insulated with foam glass gravel on the lower side and into which the underfloor heating system has been integrated. The walkable upper area has a polished surface which has been attained by using silica. No membranes or sealants or other such materials have been used. The materials are purely mineral and recyclable.
The walls are made of 100% renewable raw materials with solid wood on the inside, cellulose insulation between the timber frame and then wood fibre. The panelling on the outside was made from a silver-fir timber formwork using a ventilation level. The inside has been oiled and the timber cladding sealed. Otherwise no other treatment has taken place.

The roof is comprised of an oiled, multi-layered panel which is visible from below, with cellulose insulation in the spaces between the solid timber beams, and a cement-bonded particleboard on top. The solid wood beams then provide a level of ventilation as well as a level of formwork made from untreated boards which are covered in PVC-free roof sealant. On top of this is the 30-cm-thick roof greening pack.


Design concept: Eco-friendly construction

The whole complex has been planned and constructed to be consistent in the overall mission of being eco-friendly. The choice of materials, construction method and building management system all aim to achieve this objective. With an environmentally aware client and an architectural practice devoted to eco-friendly construction this all becomes possible due to:


Organic materials

Most materials used are environmentally friendly and locally sourced except for the mineral floor slab and the roof sealing membrane. The wood has been sourced from a distance of 450 km. No adhesives nor synthetic insulation materials or raw materials have been used. Only organic oils and potassium silicate has been applied. The insulation for the doors and windows have been installed using screws without the use of spray foam.


Innovative hot water and heating system

The supermarket is heated using concrete core activation, which is heated solely by the supermarket‘s refrigeration units and so requires a 0 heating energy. Only the air curtain is run as a high-temperature system from the central heating system.  The central system is a pellet system and is boosted by the 30-m² thermal solar installation on the rooftop. This high output from all systems is required in order to provide the restaurant with hot water as well as necessary for drying the farm’s grain, but the residential units and supermarket are also supplied.


Air renovation feature

The restaurant, just like the passive house, is supplied with fresh air through a ventilation system that has a special feature – it draws air from the flat roof’s ventilation level. This means that all the air that comes in through the 12 cm high level is preheated in the winter and precooled in the summer while on the other hand, it also ensures that moisture is removed from the membrane-free roof construction.


Rainwater use

A rainwater bypass system is also available during the summer. All surface water is diverted into a 20,000-m³ rainwater system tank, which is primarily used for the restaurant‘s toilets. Other units in the complex make use of it as well. Any surplus water is channelled into a small pond, making the outside area considerably more attractive as well as providing a habitat for fauna.



This building is located at a business village called Ecoparc Windhof that is 15km west of Luxemburg City (30, rue d`Arlon, L-8399 Windhof).


Project management




Energy concept and design: Hainarchitektur Architekten

Wood materials: Holzbau Henz GmbH

Owner and investor: OIKOPOLIS Gruppe


Time schedule

Design and construction: n.d.

Delivery and inauguration: February 2014


Surface areas / building use

New building complex (846 m2):

  • Supermarket: a single-storey building with a total of 557 m2 and 377 m2 of usable floor area
  • Passivhouse: A two-storey building over the supermarket with 289 m2 of usable floor area

Restaurant and residential units: Existing three-storey building annexed to the left side of the supermarket with 497 m2 of usable floor area.

Green areas:

  • Supermarket flat roof has a garden with a private area for the passivhouse and the remaining of 270 m2 includes 30 m2 of solar thermal panels.
  • Parking area and green area for growing vegetables over 1000 m2. This is also used as rainwater retention which feeds into the pond area.


Construction costs

Total building complex: approximately 1 M €


Envelope performance

U-Value total average is 0.22 W/m2.K

Airtightness for the supermarket is 1,18 1/h. The passivhouse has not yet been tested.


Supermarket element details

Wall façade construction (from inside to outside):

  • timber cladding oiled and sealed.
  • solid wood panel, 100% wood without any adhesives, airtight.
  • cellulose insulation.
  • wood soft fibreboard.
  • silver-fir timber formwork.


Roof construction (inside to outside):

  • veneer lumber multi-layered and oiled
  • solid timber beams with cellulose insulation
  • cement-bonded chipboard
  • 12 cm ventilation level with simultaneous preheating of the ventilation system
  • permanent formwork of untreated boards
  • PVC-free roof sealant.
  • 30 cm thick roof greening pack.


Ground floor construction (from lower to upper):

  • foam glass gravel
  • low temperature underfloor heating system
  • concrete floor slab with concrete core activation
  • polished finished floor surface (by using silica)


Passivhouse wall façade details

  • timber cladding oiled and sealed.
  • double solid timber beams with cellulose insulation
  • wood soft fibreboard
  • silver-fir timber formwork.


Energy consumption*

Estimated values are accounted according to the RGD 30 novembre 2007 - bâtiment d'habitation.


  • primary energy demand: 28 kWh PE/m2.year (class A)
  • heating demand; 64 kWh PE/m2.year (class C)



  • primary energy demand 40 kWh PE/m2.year (class A)
  • heating demand 21 kWh PE/m2.year (class A)


 GHG emissions: 6,60 Kg CO2/m2.year

(*) No information about consumption is available yet because the building has only just been recently occupied. When the requirements were calculated, heating from the cooling system was not included.


Energy systems

Heating system: underfloor heating, biomass boiler and solar thermal

Hot water system: solar thermal and biomass boiler

Cooling system: no cooling system

Ventilation system: double flow heat exchanger

Renewable systems: solar photovoltaic, solar thermal and biomass boiler

Awards and recognitions

Candidate for the Green Building Solutions Awards 2015 celebrated by Construction21


Original source Construction21 (C21)



Lessons learnt

This project has become a reference for timber frame construction as the original business model has broadened therefore creating another type of clientele. It should be noted that the original model was based on biodynamic farming since 1988 and now has expanded the concept of an even more healthy end product.

Award labels

Additional documents

Available link languages