782 Royale Belge credit Severin Malaud 4071
Commissioned by the builder Souverain 25 SA and with a view to a possible rezoning, our experts kept a close eye on the iconic Royale Belge building.
  • Client: Souverain 25 NV

  • Surface: 39.174 m²

  • Timing: 2020-2023

  • Status: Executed

The former, imposing headquarters of Royale Belge dominates the estate on Boulevard du Souverain in Brussels.

This emblematic cruciform monument measures 54,000 m2 and owes its iconic status to its external skeleton in Corten steel and façade in bronze-tinted mirror glass. In 2019, this 1960s modern castle, designed by René Stapels and Pierre Dufau, conquered a place on the heritage list.


In 2020, we were engaged by the building owner Souverain 25 to study the feasibility of the redevelopment plans that led to the building's infill today.

The feasibility study examines the possibility of passive construction and the use of renewable energy sources when renovating the building.

Very specifically, our experts gave advice on:

  • destructive testing and roof advice
  • daylight advice and glass advice, taking into account the heritage value and special properties of the original glazing
  • EPB and building code analysis
  • fire advice
  • destructive research (in collaboration with Grove+) and façade detail advice
  • study to maximise reuse in the reconversion.

Our experts kept a strong common goal in mind: to redevelop the building in the most sustainable way possible.

Jan Moens sums it up as follows: "While the building was already powerful as an office building, a visionary builder, good architects and executor as well as a specialised study team let the building outdo itself with maximum conservation as the backbone." Together, they strived to make every square meter of the building contribute meaningfully to the comfort and well-being of its users. Mission accomplished! 💪🏽

Glass consulting

Standard solar control glazing would be highly inadequate. Not only because of the required golden sheen, the quality of daylight that would bathe the interior spaces in a golden glow was also an important precondition.

Our building physics expert Robbe Verelst and daylight specialist Martijn Vyncke investigated what specifications the glass had to meet. They did this based on a thermal bridge analysis, an overheating study and a daylight study.

A market survey of existing gold-coloured glass showed that none of the existing gold glass could pass the test in terms of daylight and mental well-being. On the basis of our experts' study, glass supplier AGC developed a new glass coating using its Coating-On-Demand technique with the requested pronounced gold reflection that matches the original glass, but with much better energy performance: solar control, thermal insulation and good daylight values.

Martijn and Robbe can sleep on both their ears, this glass will have a significant beneficial impact on the mental well-being of everyone working or staying in the building. #architectsandengineerswithapurpose

Did you know
12,000 m² of high-efficiency glazing with solar control was installed.

Read more about how healthy buildings impact our well-being.
Souverain 25 2
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EPB consulting and reporting

Our energy specialists provided EPB advice during the design phase and the integrated feasibility study. They also followed up the site and handover.

The feasibility study examines the possibility of pursuing passive construction for the renovation of the building, alongside the use of renewable energy sources.

A dynamic simulation is carried out for the offices in the tower, examining various building envelope measures (insulation façade, choice of glazing). Before we can start on this, we did a thermal analysis of the opaque facade.

Read more about how we do EPB at BB.
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Construction node analysis

A thermal analysis is performed for the facade of the tower, the concrete structure under the tower and the roof structure of the former restaurant. This examines the energy performance for different insulation scenarios, along with the risk of surface condensation and/or mould formation.

Read more about what we mean by thermal analysis at BB.
A total renovation of an iconic and listed building such as the Royale Belge is no easy task and can only be brought to a successful conclusion if all team members perform their duties correctly and on time, we are therefore particularly pleased that we called on Bureau Bouwtechniek for the fire safety. ❤️ Merci Frank, we wouldn't have missed it for the world. ☺
At the request of Frank De Snoeck, we worked out the fire safety concept for the monumental building and followed up the fire safety further during the construction site.
Royale Belge Royale Belge2 Royale Belge3

Did you know that

we conducted a study on the feasibility of an energetic façade renovation on behalf of Cofinimmo back in 2013?
Besides investigating potential thermal optimisations, we also kept a close eye on solar heating loads and daylighting.

Feasibility energetic renovation

Meet the BBs who together realised this project.

From Team Façade engineering (1)

Raf 569 A3809 Gemiddeld

arch. Raf De Preter

Expert construction details
Façade advisor
E-mail |

From Team Fire (1)

CHOICE 569 A2001

ir. arch. Nadja Van Houten

E-mail |

From Team Knowledge Innovation & Technology (3)

Jan Moens kennispartner 3379

prof. arch. Jan Moens

General Director
Head of Research & Development Department
Managing Director
E-mail |
CHOICE 569 A2001

ir. arch. Nadja Van Houten

E-mail |
Raf 569 A3809 Gemiddeld

arch. Raf De Preter

Expert construction details
Façade advisor
E-mail |

From Team Renovation, Restoration & Maintenance (1)


arch. ass. Tuur Van Dijck

Advisor flat roofs
Safety coordinator
E-mail |

From Team Sustainability, Energy & Comfort (2)

B B Martijn Vyncke 8087 Large

ing. Martijn Vyncke

Energy advisor
Daylight expert
Consultant technical installations
E-mail |
BB Robbe oct2014

ir. arch. Robbe Verelst

Energy and sustainability advisor
Building physics engineer
E-mail |
TAGS: Durability| Daylight| Façade| audit| Building physics, Comfort & Well-being| Reconversion| Energy renovation