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- Leefmilieu Brussel HQ — Tour & Taxis
Europe’s largest passive office building — 700 m² of black BIPV sculpted into its curved skin
A flagship passive building at Tour & Taxis — where ISSOL® Noctis turned a curved skin into a 700 m² solar surface
An environmental agency that had to lead by example — building performance, visual identity and solar generation in a single envelope
When Leefmilieu Brussel set out to build its new headquarters at Tour & Taxis, the ambition left no room for compromise: this building had to embody sustainability, not merely comply with it. Cepezed (NL) and Philippe Samyn & Partners (BE) responded with a 16,000 m², seven-storey curved structure — one of Europe’s largest passive office buildings — designed to bring over 600 employees under one roof while achieving heating needs below 15 kWh/m²/year.
ISSOL® was selected to design and manufacture the BIPV components — an essential element of both the energy strategy and the building’s visual identity. The dark, refined surface of the ISSOL® Noctis modules flows with the building’s curved geometry, echoing the industrial tones of the surrounding Tour & Taxis site. From the street, the building reads as a sculpted solar form — earning it the affectionate nickname “The Toaster” from Brussels locals.
700 m² of black BIPV across a highly complex geometry — blending with aluminium and triple glazing throughout
- ±700 m² of custom ISSOL® Noctis BIPV glass modules, fully integrated into the curved façade and roof structure — matched to the building’s aluminium and triple-glazing composition in both colour and module geometry
- Monocrystalline black solar cells delivering a sleek, uniform black finish that flows with the building’s curved form — electricity generation and solar shading combined in a single product layer
- ±100 kWp installed power generating an expected 88,000 kWh annually — directly reducing the building’s operating costs by over €200,000 per year alongside the passive house strategy
- Passive House performance confirmed via PHPP: heating needs below 15 kWh/m²/year; the BIPV shading function contributes to limiting summer solar gain without a separate brise-soleil
- Holistic energy concept: geothermal heating and cooling via heat pumps and ground loops; concrete core activation; dual-flow mechanical ventilation with heat recovery; extensive daylighting via a central atrium
- BREEAM Excellent certification achieved alongside Passive House (PHPP) — both demanding independent certification frameworks met in a single building
Why it fits: The Leefmilieu Brussel HQ brief was unambiguous: the building envelope had to read as a single, coherent dark surface — no contrast between active and non-active panels, no visual disruption to the curve. ISSOL® Noctis, with its fully opaque monocrystalline black cell matrix, delivered exactly that. Across 700 m² of curved façade and roof, the modules blend with the aluminium and triple glazing in colour, surface and module rhythm, so that the solar skin and the building architecture are indistinguishable — precisely the condition Cepezed and Philippe Samyn & Partners set from the outset. The integrated shading function eliminated the need for a separate shading layer, and the ±100 kWp of generation contributes directly to the passive house energy balance.
Parameters for rapid evaluation
| Parameter | Value | Notes |
|---|---|---|
| Application | BIPV curved façade + roof | New-build passive office; 16,000 m²; 7 storeys; highly complex curved geometry |
| ISSOL® solution | ISSOL® Noctis | Fully opaque black BIPV glass modules; monocrystalline cells; uniform black finish; custom dimensions per panel |
| BIPV surface | ±700 m² | Integrated across curved façade and roof structure |
| Installed power | ±100 kWp | Clean energy generation; contributes to passive house energy balance |
| Annual yield | 88,000 kWh/yr | Expected annual solar production |
| Dual function | Generation + solar shading | BIPV skin replaces separate shading layer; integral to passive house summer performance |
| Energy savings | >€200,000/yr | Combined passive house + BIPV + geothermal + heat recovery strategy |
| Heating need | <15 kWh/m²/yr | Passive House (PHPP) verified |
| Heating + cooling | Geothermal heat pumps | Ground loops; concrete core activation for stable indoor temperatures |
| Ventilation | Dual-flow with heat recovery | Mechanical + natural ventilation; central atrium for daylighting |
| Completed | 2014–2015 | Tour & Taxis, Brussels, Belgium |
“A solar façade that looks and performs like part of the original design, not an afterthought — the BIPV skin flows with the building’s curved geometry, echoing the industrial tones of the Tour & Taxis site.”
Leefmilieu Brussel HQ — Tour & Taxis, Brussels, 2015
700 m² of black BIPV — from raw steel frame to sculpted solar skin
