Markku Vuorisalo, Engineering Director at Marioff, speaks to International Fire Buyer about the landmark Notre Dame project.
After the Notre Dame fire, water mist technology played a pivotal role in protecting the cathedral during restoration. Markku Vuorisalo explains how this innovative system safeguarded the heritage site and its wider implications for fire protection worldwide.
Markku, can you start by introducing yourself and your background?
I’ve been in the fire protection industry for 25 years, serving in a variety of roles across project management, business development, sales, and marketing. For the past nine years, I’ve been leading the engineering team at Marioff.
My background is in engineering, and I’ve also been involved with the International Water Mist Association (IWMA) for around nine years now. Additionally, I sit on the European Fire Sprinkler Network Council, where I’ve been a member for the past six years. I’m happy to contribute to the water mist industry in many different ways.
One particularly fascinating example of your work is the Notre Dame Cathedral project. Could you walk us through how that project came about and how water mist protection was integrated?
The planning for the Notre Dame fire protection project began in late 2019, after the devastating fire in April of that year. It took several months to assess the damage, determine the necessary scope of refurbishment, and decide what measures would be required to prevent another such incident in the future.
One conclusion was clear: the rebuilt cathedral would need an effective fire protection system, incorporating both passive and active measures. Given that water mist is among the most effective modern fire protection technologies — particularly in terms of cooling and limiting water damage — it was included in the project through a public tender process. That’s how we at Marioff became involved.
Once you were engaged, what were the critical steps in moving from concept to actual installation?
There were several key steps before the final design and installation. The French National Institute for Industrial Environment and Risks (INERIS) was selected to assess which passive and active solutions should be considered. Their evaluation highlighted water mist technology because of its superior cooling capability and low water consumption compared to low-pressure mist and traditional sprinkler systems.
We participated in the public tender process starting in August 2022, and the contract was finally awarded to Marioff in March 2023. One important requirement of the tender was to perform a specific fire test programme, which INERIS planned and organised.
In that test, we built a simulated attic structure to replicate the cathedral’s wooden roof space — the area that needed protection. The attic was ignited and allowed to burn until temperatures reached about 1,000°C. At that point, the water mist system was activated. Almost immediately, the temperatures in various measured locations dropped to around 50°C, and the mist effectively pushed the flames down.
