Following the devastating fire that damaged the Notre-Dame de Paris cathedral last month, local firm Vincent Callebaut Architectures has unveiled its vision for the iconic building to be restored. The firm imagines it being topped by a new glass roof and a spire, and for it to receive a significant sustainable upgrade.

The concept – and to be clear it is only a concept, not a definite plan – is named Palingenesis and brings to mind NYC's St. Patrick's Cathedral, which recently received an AIA award for its sustainable makeover.

While the undamaged parts of the building look essentially the same, Callebaut radically reimagines the upper areas destroyed in the fire. His proposal would create a new spire and wooden frame made from CLT (cross-laminated timber) beams, with carbon fiber slats. Covering the building would be a complex glazed roof that allows for lots of natural light inside, incorporates ventilation, and features advanced solar panel-like tech that turns sunlight into electricity.

"From the four gables, the original geometry of the 10 m (32 ft)-high attic has been respected," says Callebaut. "As we move towards the transept cross, its triangular section and steep, 55-degrees pitched roofs gradually stretch to shape a vertical spire.

"The new wooden frame is covered with a three-dimensional crystal glass dress subdivided into faceted diamond-shaped elements. These crystals consist of an organic active layer, made of carbon, hydrogen, nitrogen and oxygen, which absorbs light and transforms it into power. This energy, stored in hydrogen fuel cells, will be directly redistributed throughout the cathedral."

Elsewhere in the cathedral would be a large garden devoted to contemplation and meditation. A farm would also be installed in planters, with an integrated system of aquaponics and permaculture.

According to the firm, the farm could produce up to 25 kg (55 lb) of fruit and vegetables per sq m (3.2 sq ft) per year, allowing up to 21 tons of food to be harvested each year. This could then be given away to Parisians who need it most.

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