LT2A and OPEN Architectes Thread a Brick and Glass High School Through a Wooded Belgian Campus

Adding to a school campus that already has a strong identity is harder than starting from scratch. At Collège Cardinal Mercier in Braine-l'Alleud, LT2A and OPEN Architectes faced that problem directly. The campus is a set of separate pavilions scattered through a dense wood, and they share an identity through a deliberately limited palette of materials. The new 3,000 m² secondary school building, completed in 2023 under lead architects Paul Emmanuel Lambert and Foucault Tiberghien, had to join that family without simply imitating it.

What interests us is how quietly the architects handled this. The building doesn't announce itself. It splits into two characters: a solid brick volume with deep concrete window surrounds, and a long glazed pavilion carried on slender columns. Between them sits a small slate-spired chapel that the new building clearly organizes itself around. The result reads less like a new school block and more like a careful rearrangement of what was already there.

A Building That Sits Behind the Trees

From the air, the flat-roofed building almost disappears into the canopy, with the chapel roof and neighboring houses holding equal visual weight. At ground level you rarely see the school whole. You catch it in fragments between linden trunks, moss-covered bark and drifts of fallen leaves.

That fragmentation looks intentional. The building is kept low and horizontal, so the vertical trunks become the dominant rhythm and the architecture plays the background. On a wooded site where the trees are the real heritage, that is the correct hierarchy.

The Chapel as Anchor

The small brick chapel is the emotional center of the composition. Seen from outside, the glazed two-storey facade works as a neutral backdrop, a clear screen that lets the spire and its slate roof stand out against it. The designers made no attempt to compete with it in mass or ornament.

The upper-floor corridor makes the relationship reciprocal. Timber columns frame floor-to-ceiling glass that looks straight onto the round chapel among bare winter trees. Circulation becomes a viewing gallery. Students moving between lessons see one of the campus's oldest markers from a new height, which is a good argument for letting a corridor do more than move people.

Brick, Concrete and the Shared Palette

The solid half of the building is where the campus's material language carries over most directly. Pale brick walls are punctured by windows set in deep, pale concrete surrounds, stacked in two disciplined rows. The surrounds give the openings depth and catch tree shadows across the facade, so the wall changes through the day without any added decoration.

At the corner, tall concrete-framed windows reflect the ivy-covered wood, so the glass shows the forest back. This is continuity without pastiche: the brick ties the volume to its neighbors, and the proportions and crisp framing date it clearly to now.

The Glazed Pavilion and Its Columns

The second character is lighter in every sense. A long glazed pavilion runs behind slim grey columns, and at one point a triangular support breaks the regular grid. Where it meets the brick wall, tall concrete fins under a curved canopy set up a deeper rhythm, almost a cloister edge.

Then there is the round white disc, which appears as a panel and, at dusk, as a freestanding sculptural element. It is the one playful gesture in an otherwise sober vocabulary. We'd argue it earns its place: in a building this restrained, a single circle becomes a landmark and a meeting point without shouting.

Evening Light in the Wood

After dark the balance flips. The glazed facade becomes a lantern among bare trunks, and the receding line of columns along the paved path pulls you toward the chapel. For a school that also hosts evening activities, this matters. The building gives the dark wood a lit, legible edge without floodlighting it.

Classrooms Built From Honest Surfaces

Inside, the material restraint continues. Classrooms pair exposed concrete walls with wood-wool ceilings and light timber furniture. The wood-wool almost certainly helps acoustics in rooms full of teenagers, and it brings texture without needing applied finishes.

The multipurpose room is the most pragmatic space here: folding partitions, exposed spiral ducts and mobile whiteboards make it an adaptable shell. The science classroom, by contrast, frames a tall window onto autumn trees. Whatever the subject, the wood stays in view, which is perhaps the building's most consistent pedagogical idea.

Plans and Drawings

The site plan confirms the pavilion logic of the campus: dark footprints scattered among sports pitches and paths, none dominating. The closer site drawing shows the new building as a long cross-shaped form with angled wings that bend around a courtyard and existing tree canopies, rather than cutting through them.

The floor plans show the organizing move clearly. A long spine, hatched in red as circulation, runs the length of the building, and classrooms hang off it in angled wings. The angles let the building follow the trees and the chapel, and the spine keeps navigation simple.

Why This Project Matters

Much school architecture tries to brand an institution through a single bold gesture. Collège Cardinal Mercier takes the opposite approach. LT2A and OPEN Architectes treated the existing campus, its limited material palette, its scattered pavilions and its chapel as rules to work within. The new building gains its identity by extending that logic rather than breaking it.

The lesson for you as a designer is about calibration. Brick ties the building to what came before, glass and slender columns keep it light among the trees, and one round disc gives it a memorable focal point. Restraint here isn't timidity. It is a precise reading of a place whose real value lies in its landscape.

Collège Cardinal Mercier by LT2A and OPEN Architectes (lead architects Paul Emmanuel Lambert and Foucault Tiberghien), Braine-l'Alleud, Belgium. Area: 3,000 m². Completed: 2023. Structural engineering: ADEM Bureau d'étude. Photography: Utku Pekli.

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