Architects propose a Gothic and biomimetic roof for Notre Dame

Belgian ecological architecture firm Vincent Callebaut Architectures (VCA) pays tribute to the Notre Dame with their Gothic and biomimetic forest proposal.
Images © Vincent Callebaut Architectures

On April 15, the world watched as the Notre-Dame in Paris, constructed eight centuries ago, nearly saw its end in the historic fire that devoured its roofs. Now, Belgian ecological architecture firm Vincent Callebaut Architectures (VCA) proposes a design for the cathedral that brings history, science, art, and spirituality together.

The firm presents a transcendent project, a symbol of a resilient and ecological future that offers a set of solutions inspired by biomimicry that VCA defines as a fairer symbiotic relationship between humans and nature.

A biosourced contemporary spire

The Palingenesis project, in Greek meaning ‘rebirth’ or ‘regeneration’, aims to assimilate the venerable stone nave to blend in naturally as a vegetal graft.

From the four gables, the original geometry of the 10-m (33-ft) high attic has been respected. As it moves toward the transept cross, its triangular section and steep, 55-degrees pitched roofs gradually stretch to shape a vertical spire.

Respecting the inherent principles of descent of the structural loads of the building toward the flying buttresses and the inner fasciculated pillars, the four roofing lines and the four lines of the roof’s ribs bend and join together producing a parametric and light geometry.

Constructed with cross-laminated timber (CLT) beams pre-stressed with carbon fiber slats, the new oak frame seeks to use the minimum amount of material needed to ensure a low-carbon footprint, while offering the greatest transparency to the cathedral.

The four hip rafters are oriented toward the cardinal points. Between the four ridges, which give the roof its sophisticated character, their curves reincorporate one above the other the monumental, wrought-copper statues of the twelve apostles.

The rooster found in the rubble the day after the disaster will crown the spire again.

Solar and ventilated roof
A new architectural ‘graft’ will turn Notre-Dame into a positive energy building, designed to produce more energy than it consumes. Through energetic solidarity with the body of the historic monument, the contemporary, three-dimensional Gothic stained glass graft produces all the electricity, heat, and passive ventilation the cathedral might require.

To avoid any greenhouse effect, 3D crystalline scales open at the bottom of the frame along the acroterion of the nave and transept, creating a natural airflow toward the top of the spire, which mimics a wind-powered chimney.

Further, this roof-spire in the cathedral attic provides a thermal buffer space, which accumulates hot air in winter, and vents with fresh air in the summer through the evapo-transpiration of plants.

Urban farm

At its heart, the Palingenesis project features a garden serving aesthetic and nourishing purposes.

This urban farm is arranged atop the Latin-cross plan of the roof and set in planters, which essentially redraw the layout of six-part vaults on the ground. This geometric garden ‘à la française’ relies on a double-deck structure with light soil to grow its fruits and vegetables along the nave, from East to West, from the two towers to the apse. In the North-South axis, the roofs of the transept hosts aquaponic basins feeding plants with natural, fish fertilizers. Moreover, these water mirrors expand the place by reflecting the rose windows on the North and South side gables.

A choir bathed in natural light
The large arched vault of the intertransept would be rebuilt in structural glass around its four stone ribs, pushing the thrust toward the corners. Natural light would highlight the emblematic identity of this place at the intersection of the main branch of the nave and the transept. The history of the place and its terrible fire would be retranscribed architecturally, offering a new divine atmosphere from the narthex of two spans located between the towers.

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7 comments on “Architects propose a Gothic and biomimetic roof for Notre Dame”

  1. I have been watching the news on this. I’m thinking that the only comment we could make as specifiers and facilitators is that we stand ready to do our work, no matter which way the reconstruction is settled. We’ll specify anything and everything, so in many ways it doesn’t matter to us.

    Overall the reconstruction is being used by various factions to forward their agendas. Secular groups are trying to make it into a national museum of sorts, or monument. The Church still wants control of course, other groups want it to be modernized to repudiate the past. Unless the government just strong-arms a path forward, I think it will be embroiled in controversy for some time.

  2. It’s difficult to understand why not just restore it according to its historical nature – a medieval majestic Gothic CATHEDRAL intended to honor God.

  3. Notre Dame is a one-off; no need to do gymnastics to make it energy efficient or engage in reputation building “biomimetic” politics and spirituality. To begin with, it does not consume much energy, so lets just restore it as close to the original as possible – as soon as possible – but with a new steel truss roof (AKA, non-flammable).

  4. According the the United States guidelines for restoration of historic structures this design would not work. In my opinion this “hat” totally destroys a masterpiece of architecture and seems to poke fun at Christianity’s centuries of holy faith and devotion. Perhaps the designers did not consider this. Otherwise their design is quite interesting in spite of being inappropriate. The impact on me is not spiritual, as the original creators intended, but rather scientific, mechanical and foreign. If it were a new structure built somewhere else I think it would be fantastic!

  5. I seldom criticize design inasmuch as beauty is in the eye of the beholder. I make exception to my normal stance and offer that it is totally out of character to the purpose for the cathedral’s purpose. It is to honor and worship our creator. It is not intended to aggrandize an architect. It is not the time or place to be cute for display of current whims.

  6. Historic structures no matter how cast in stone they maybe had been always reflection of the times when they were built. So many of the Cathedrals we know have been through the process of renovation so much as some of them have elements of different styles on them, others have complete substituted older ones,
    The roof of Notre Dame was destroyed, God giving us the opportunity to rebuilt it with techniques and uses that reflect our times, wouldn’t it be beautiful to have a same proportioned glass roof on a stainless steel frame where masses can be performed in the attic? Was not the dream of Gothic architects to let the sky enter the nave so they built (and rebuilt) taller and taller stainless glass windows? Wouldn’t it be the quintessential to have the nave right in the sky?
    No, it was decided by the same minds that dream in having the masses be said again in Latin as in the XII century, that the attic be again room for rats and quasimodos.

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