At Notre-Dame, a new system to fight fires "directly"

Unprecedented in a cathedral in France, this misting mechanism is the trump card that Notre-Dame adopted during its reconstruction to strengthen its fire protection system.

"The idea was to allow us to react more quickly but above all to ensure that the monument could fight a fire itself," Rémi Fromont, one of the three architects in charge of the Notre-Dame construction site, which reopens its doors on December 7, explained to AFP.

On the evening of April 15, 2019, when flames ravaged the wooden frame of Notre-Dame, the monument's fire-fighting system showed its limits.

At 18:18 p.m., a fire alert message did indeed appear on the security PC control screen, triggering a general alarm and the evacuation of the premises. But it took two "reveals of doubt" by security agents to confirm the presence of flames and alert the firefighters.

Around thirty precious minutes were lost, during which the fire, the origin of which remains undetermined to this day, began to pierce the lead roof.

During the reconstruction, it quickly became apparent that this fire-fighting system needed to be completely redesigned without disfiguring the building, a 12th century Gothic masterpiece that is one of the most visited monuments in Europe.

"After the disaster, we couldn't just have a heritage response and we couldn't have a response that only took into account the issue of fire safety. We had to work on both," emphasizes Rémi Fromont.

Minimize the damage

"The first challenge was that it had to not look ugly," Eric Lazzari of Détection électronique française (DEF), one of the companies that installed the new fire-fighting mechanism, recently explained to AFP.

The choice therefore fell on a misting system which snakes along the medieval framework up to the spire and is activated automatically in the event of an alert, creating a water mist capable of reducing the ambient temperature by 500°C in one minute and smothering the flames by driving out the oxygen.

This system also has the great advantage of preserving the premises more. "The main problem with traditional water extinguishing systems is that the water runs, trickles and causes damage, particularly to wood, whereas misting has the same ability to extinguish the fire but with a reduced impact," according to Eric Lazzari.

This mechanism, used in data centers or highway tunnels, has gradually made its appearance in heritage sites. It is used in St. Patrick's Cathedral in New York, the Bristol Old Vic theater in the United Kingdom and the Duchess Anna Amalia Library in Germany.

At Notre-Dame, to complete the arsenal, around fifty thermal cameras have appeared to detect abnormal sources of heat in high-risk areas, particularly on the electrical panels scattered throughout the building.

By also integrating smoke detectors, Notre-Dame now has more than 300 detection points, according to DEF.

"If you have a circuit breaker that burns in an electrical cabinet, the thermal camera will detect that there is a fire in the cabinet and automatically activate the water mist. So nothing can happen without us knowing," says Mr. Lazzari.

According to him, in terms of extinguishing capacities, Notre-Dame has gone, since the 2019 fire, "from 0 to 100".

Rémi Fromont is also convinced of the benefits of the new system but assures us with a smile: "I don't want to test it."

From the origins to the reopening: ten important dates of Notre-Dame de Paris

From its construction in the 8th century to its reopening on December XNUMX, five years and eight months after a devastating fire, here are the ten important dates of Notre-Dame Cathedral, the Gothic emblem of Paris.

1160: first stones

Construction of the cathedral began around 1160 under the leadership of the ambitious Bishop of Paris, Maurice de Sully. The bulk of the construction was completed in just one century.

The Gothic building was then the "first church to have vaults more than 30 metres above the ground", underlines the medieval historian Maxime L'Heritier.

1239: The Crown of Thorns

Taken away in a hurry on the evening of April 15, 2019 by the cathedral manager while the framework was burning, the legendary Crown of Thorns of Christ was placed for the first time in the cathedral on August 19, 1239, by Saint Louis.

Another precious relic, the tunic that, according to tradition, the monarch wore that day, was also saved from the disaster.

1455: rehabilitation of Joan of Arc

The first session of the rehabilitation trial of Joan of Arc was held on November 7, 1455 at Notre-Dame, 24 years after her condemnation to the stake in Rouen.

The trial which was then held in Rouen declared, in July 1456, "null, void, without value or effect" the judgments of the court which had condemned her.

1594: Te Deum for Henry IV

At the end of the 22th century, the Wars of Religion divided France between Catholic and Protestant Leaguers. After having abjured Protestantism, King Henry IV established his power by entering Paris on horseback on 1594 March XNUMX, which was still in the hands of the Leaguers.

His journey through Paris takes him to Notre-Dame, where he enters to pray. A Te Deum is then given as a sign of national reconciliation.

1793: Temple of Reason

Statues of kings destroyed, treasure scattered, bells melted: the French Revolution did not spare Notre-Dame. In 1793, it lost its status as a cathedral, became the "metropolitan church of Paris" and then transformed into the "Temple of Reason".

Closed for two years to Catholic worship and transformed into a wine depot, Notre-Dame nevertheless escaped the fate of Cambrai Cathedral, which became a "stone quarry" and disappeared forever, underlines the historian specializing in the French Revolution, Hervé Leuwer.

1804: Coronation of Napoleon

On December 2, 1804, Notre-Dame was the scene of the lavish coronation of Napoleon I as "Emperor of the French." The ceremony, which took place in the presence of Pope Pius VII, lasted nearly five hours and was immortalized by the grandiose composition of the painter Jacques-Louis David.

1831: Esmeralda enters the scene

Published in 1831, the novel Notre-Dame de Paris features the gypsy Esmeralda and the hunchback Quasimodo but has the cathedral as its main character: Victor Hugo's book is a plea for the preservation of medieval heritage after centuries of contempt.

1859: the arrow of Viollet-le-Duc

In a pitiful state, the cathedral was the subject of an ambitious restoration program from 1844 under the leadership of the architect Eugène Viollet-le-Duc. The project, which spanned nearly twenty years, was marked in 1859 by the construction of a new spire, a medieval element that had been dismantled during the Revolution.

1944: de Gaulle under machine gun fire

On the evening of August 24, 1944, the cathedral's "Emmanuel" drone sounds its bass vibration: General Leclerc's 2nd DB has just entered Paris. On the 26th, General de Gaulle travels through the capital as a liberating hero. He ends his journey at Notre-Dame where he attends a Magnificat. The aisles are packed to the rafters despite the bullets from snipers hidden in the galleries, which cause stone chips to fall on the crowd.

2019: a fire that stuns

On the evening of April 15, 2019, the cathedral's framework caught fire. The fire brought down the spire. The images of the medieval jewel on fire stunned millions of people.

The towers were narrowly saved. The next day, President Emmanuel Macron promised to rebuild in five years and launched a national subscription that raised 846 million euros.

On December 8, 2024, Notre-Dame reopens its doors.