Architecture of the Luxembourg Pavilion in Osaka: Circular and responsible

Circularity at the heart of design

The Luxembourg Pavilion at the Osaka 2025 Expo was designed by the Luxembourg architectural firm STDM according to the principles of circularity.

It is a temporary structure intended for 12 months' use. The first six months after the construction were used to put together the scenography and to commission the pavilion for opening. The following six months cover the operation period throughout the Expo from 13 April to 13 October 2025.

In this context, to ensure maximum adherence to the philosophy of circularity, two questions were addressed. Firstly, how can a short-term use structure justify the consumption of the resources and energy required for its construction? Which led to the second question: How do you substantially reduce the consumption of materials?

These considerations prompted the team of architects from STDM to think about the future of the pavilion and what would happen to the materials after the end of the exhibition from the very start of the planning phase. As a result, three strategies linked to circularity took on greater significance:

• Refuse: Select only the materials required to achieve the objective.
• Re-use: Use standard materials, in accordance with Japanese norms. This opens the path for re-use in a Japanese context after the exhibition.
• Regenerate: Recycle materials locally following high-quality sorting at the end of the exhibition.

This is how the concept "design for disassembly" came to the fore. This approach puts the focus on designing buildings and products in a way that facilitates their disassembly at the end of their first cycle of use.

From positive frugality to the re-use of the "Major Four"

The "rethink" strategy resulted in the design of an above-ground construction that was as lightweight as possible. In processed products, there is in fact a direct link between their weight and the energy consumed during their production and installation; it was therefore important to make the construction lightweight, by using only the components that were strictly necessary. This positive frugality maximises the resources used.

From their side, within the strategy for "re-use", the architects considered the "Major Four", namely:

• The use of concrete megablocks, as the main elements for the floating foundations. These blocks are easier to disassemble in comparison to conventional poured concrete foundations. Once they have been cleaned and since the blocks are not damaged, their potential for re-use is considered as very high.
• The creation of an extremely lightweight and high-performance membrane roof. This limits direct solar impact and therefore also reduces the pavilion's energy needs for cooling. This membrane can be re-used either entirely to reconstruct the pavilion, or in smaller sections for design objects or accessories.
• The use of thin, lightweight, high-performance steel sections to create the load-bearing structure for the exhibition zones. These were assembled mechanically to facilitate disassembly, which means they can be re-used as they are or recycled.
• The cladding on the external walls and facades of the exhibition zones was made from formwork panels in accordance with local standards. These were arranged in an overlapping design so that they can be removed easily without being cut, thus preserving their quality for future use.