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Meet the company using discarded oyster shells to cut energy costs and keep France's buildings cool

A Paris rooftop is painted white
A Paris rooftop is painted white Copyright Cool Roof France
Copyright Cool Roof France
By Hannah Brown
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Cool Roof France has found an innovative way to use the 130,000 tonnes of waste oysters produced every year in France.


As heat waves continue to scorch Europe, many of us are looking for cheap and innovative ways to keep our homes or workplaces cool.

While air conditioning often proves effective, its environmental cost contributes further to the climate crisis.

So what if we look into the past and to other parts of the world for inspiration and start painting our roofs white?

“This technology is just pretty old actually, but this is quite innovative to make it so technical,” says Julien Martin Cocher, deputy CEO of Cool Roof France.

But does having a white roof really make a building cooler?

What is oyster shell roof paint?

Cool Roof France (CRF) is on a mission to reduce the ambient temperature inside buildings in a sustainable and cost effective way.

Traditional paint is made up of calcium, solvent and water.

In France, more than 130,000 tonnes of oyster shells are thrown away every year. CRF takes a few tonnes of this waste and uses the outer part of the shell - which is made from calcium - to replace the traditional calcium in its paint.

Cool Roof France
The outside of an oyster shell is made of calcium.Cool Roof France

“The oyster was at the beginning just to use a waste that we are finding quite easily in the west part of France and to replace this calcium that we are usually finding [in paint],” Julien explains.

Its innovative team of scientists soon discovered that the oyster shell maximises the paint’s performance and makes it more durable.

Can white paint make my home cooler?

CRF’s oyster-enriched, thermo-reflective roof paint is applied in three layers. The first two layers make it a durable product which will last for around 20 years.

By adding the third layer, the paint is able to reflect 90 per cent of the sun’s rays away from a building.

This results in an average temperature reduction of six to seven degrees Celsius.

“Usually companies are using AC and when they are using AC, that means that if we are lowering the temperature, we manage to reduce the AC use.

“By reducing the use, we are also dropping down the energy consumption for the AC,” Julien adds.

“So that means, when we are getting minus six, minus seven degrees Celsius we manage to demonstrate that we are getting between 30 to 50 per cent less energy consumption, which is huge.”

Cool Roof France
Cool Roof France are able to paint a 10,000m² roof in one week.Cool Roof France

Cool Roof France has already painted many shop, hospital and office roofs and the results are astounding.

In France, the company has worked closely with the police and government to paint the roof of a sniffer dog handling unit. The ambient temperature of the building was reduced by 10 degrees Celsius.


Last year, schools across Europe were forced to close because it was too hot for the children to be inside.

“We shouldn't fall into this kind of situation,” Julien says.

“We have 1 billion AC (air conditioning units) today. We estimate that we may get 5 billion in 2050. AC is a solution that is making some cold inside the building by making some hot outside. So we are all impacted by this kind of crazy solution.

“Today with a white paint, this is super smart and so easy to implement.”

Can I paint my own roof white with Cool Roof France?

Currently, Cool Roof France mainly works with businesses, schools and hospitals to reduce the temperature inside buildings filled with hundreds of people.


Its staff are able to paint the roof of an office building much quicker than the same area across multiple homes.

By painting many large roof areas white in an urban environment it helps to fight against the urban heat island effect. This is when cities suffer from much higher temperatures as the heat is contained by tall buildings and large amounts of asphalt. Cooling down bigger buildings can help reduce the overall temperature of a city or town.

But fear not, if you do like the idea of a white roof for your home (and have a love of DIY), CRF also sells its thermo-reflective roof paint via its site.

Using white paint for good around the world

With every building they paint, Cool Roof France monitors and evaluates its product’s performance. It is constantly innovating when it comes to paint.

The company also uses 10 per cent of its profits to help fund projects to support people living in heat vulnerable areas.


“Last year we went to Senegal, painting 30,000 square metres of buildings, schools, hospitals, individual houses and just to help people because this is part of our DNA,” says Julien.

“We just want to make sure that we are going beyond because today we are all suffering from these daily heatwaves.”

Watch the video above to learn more about this innovative roof paint.

Video editor • Hannah Brown

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