What if the solution to the overheating of our buildings could be found in our Christmas plates? French company Cool Roof is innovating by transforming oyster shells into roofing material. It's a technology that could revolutionise our approach to thermal insulation, while at the same time putting our waste to good use.
The black roof problem: a thermal bomb over our heads
Have you ever thought about the temperature of roofs in midsummer?
"When the outside temperature is 35°C, if you have a black bituminous membrane, it will rise to 70°C, or even a little more," explains Margaux Grand, Regional Sales Manager at Cool Roof.
The findings are alarming: 80% of roofs in most European countries are covered with these black membranes, which act like giant radiators. (this is particularly the case for sheds, warehouses, factory roofs, department stores, etc.).
This overheating has disastrous consequences:
- Air conditioners, often installed on roofs, suffocate in this extreme environment and consume much more electricity, for less output
- Materials deteriorate prematurely: "The membrane will expand and contract... and little by little it will have a crocodile skin effect".
- The heat penetrates the buildings, turning the top floors into furnaces.
The solution? A high-tech white coating... made from oyster shells!
Cool Roof's innovation is as simple as it is ingenious: transforming recycled oyster shells into a white coating heat-reflective.
"We recover the oyster shells once they have been eaten, in a recycling process to prevent them from being thrown away", explains the representative.
The shells are then mixed with other products to producea reflective paint that is then sprayed onto the roofs. The roofs, which were black (because they were tarred), are now all white.
And the results are spectacular:
- Roof temperature drops from 70°C to 35°C in summer (no more heat build-up on the roof)
- The indoor temperature drops by 4 to 8 degrees depending on the temperature.building insulation (because the roof transmits much less heat, and there is no longer any greenhouse effect)
- The life of the roof's bituminous membrane is extended by an average of 10 years
Precise application for lasting results
To ensure that the coating is as effective as possible, Cool Roof uses a 3-coat application:
- A first coat of base coat
- A second cross-coat to "fill in all the rough spots".
- A final "top coat" that guarantees a 10-year lifespan
"After ten years, we reapply a coat of top coat and then we last for twenty years," explains Margaux Grand.
An unexpected impact on solar panels
Innovation goes even further. This white coating significantly improves the performance of solar panels.
Why?" Because solar panels function fully at 25 degrees. Each additional degree reduces their efficiency by 0.85 points", explains Cool Roof.
In a traditional environment, panels can lose up to 15% of output due to heat.
With Cool Roof, this loss is only 5 to 7%.
To prove this, the Cool Roof teams have set up a miniature demonstrator measuring the efficiency of solar panels with and without thermo-reflective paint.
Versatile technology
The coating is not just for shed roofs, it can be adapted to a wide range of surfaces:
- Conventional bituminous membranes
- Steel tank cladding (with a special primer)
- Tiles (under certain conditions)
- Terrace slabs (with a minimum slope)
Innovation can therefore also involve roofs of apartment blocks and detached houses (You should, however, take into account the need to clean the roof every year to ensure the longevity of the coating).
A solution for the future
This technology meets three major challenges:
- Reducing the energy consumption of buildings
- Waste recovery (oyster shells)
- Improving the thermal comfort
At a time when heat is becoming a major issue in our cities, Cool Roof proves that it is possible to transform our waste into innovative solutions for a more sustainable future.
In a nutshell, Cool Roof reflective paint is...
- A reduction in the building's interior temperature of 4 to 8°C
- A lifespan of 20 years with 10 years' maintenance
- Improved photovoltaic efficiency: up to 10%
- Compatible with 80% roofs