Our CEO, María Saiz, recently joined La mecánica del caracol, the science programme on Radio Euskadi, to discuss one of the greatest challenges facing today’s cities: the Urban Heat Island effect. During the interview, she explained how PhotoKrete’s technology can significantly reduce the surface temperature of buildings and pavements, improving thermal comfort, lowering energy demand and helping cities adapt to climate change.

Heatwaves are becoming increasingly frequent and intense. As cities face this growing challenge, they need innovative solutions that complement conventional urban planning and energy-efficiency strategies.

At PhotoKrete, we have developed a photonic mortar capable of significantly reducing the surface temperature of buildings and pavements through passive radiative cooling—a technology that dissipates heat without consuming energy.

The interview, conducted by Eva Caballero on La mecánica del caracol (Radio Euskadi), coincided with our participation in BIND Demo Day. During the conversation, María Saiz discussed the origins of our technology, how it works, the results achieved so far and PhotoKrete’s next steps.

Key topics discussed with María Saiz

✔ What makes photonic mortar different from conventional concrete.

✔ How passive radiative cooling technology works.

✔ The results obtained through laboratory testing and real-world applications.

✔ The solutions currently being developed by PhotoKrete.

✔ How years of scientific research have evolved into a technology company.

✔ The next steps towards bringing this innovation to market.

How does PhotoKrete’s photonic mortar differ from conventional materials such as concrete?

The main difference lies in its thermal performance. As María Saiz explains, while conventional cement can reach surface temperatures of around 65°C on a hot summer day, PhotoKrete’s photonic mortar can lower those temperatures by more than 30°C.

“When applied to rooftops, this technology can significantly reduce the demand for air conditioning. When used on urban pavements, it helps lower ambient temperatures during heatwaves.”

This performance is based on a physical principle that sets our technology apart from conventional construction materials.

“It’s not simply that the material doesn’t get as hot—the material itself actively dissipates heat into outer space.”

From the laboratory to the city

Our technology harnesses a natural phenomenon known as passive radiative cooling.

By combining carefully engineered radiative and emissive properties, the material minimises solar heat absorption while efficiently releasing heat through the atmospheric window, a specific portion of the electromagnetic spectrum through which thermal energy naturally escapes from Earth into space.

By taking advantage of this natural process, the material cools itself passively without electricity, mechanical equipment or additional energy consumption.

This cooling process operates continuously and requires no auxiliary systems.

Proven performance under real-world conditions

During the interview, we shared some of the results achieved throughout the development of the technology.

One of the most demanding testing campaigns took place in the Tabernas Desert (Almería, Spain), one of Europe’s regions with the highest levels of solar radiation.

In addition, a rooftop installation at Tecnalia’s Kubik building in Bizkaia, which has been in operation for more than two years, continues to demonstrate the material’s performance under real operating conditions.

As María Saiz explained, the system maintains its properties over time, shows no signs of degradation and continues delivering the same cooling performance.

Applications for construction and building renovation

PhotoKrete is developing a range of solutions for the construction industry.

These include mortars for energy-efficient building renovation, walkable roofs, facing bricks, urban pavements and paving slabs for public spaces.

One of the technology’s main advantages is its ability to be applied to existing buildings as a surface layer. This makes it possible to upgrade buildings through renovation projects without altering their structural design.

From research to market

The interview also addressed one of the greatest challenges faced by scientific innovation: transforming years of research into an industrial product.

At PhotoKrete, we are scaling up production while developing new products together with industrial partners.

Our goal is to facilitate the integration of this technology into both new-build and renovation projects, helping create cities that are better prepared for the impacts of climate change.

“This is no longer just about temperature; it’s about urban health”

This statement captures the purpose that drives our work: developing solutions that enable cities to become more comfortable, more energy efficient and better equipped to face the challenges of climate change—ultimately improving quality of life in urban environments.

Listen to the full interview on Radio Euskadi

If you would like to learn more about how our technology works, the results achieved so far and PhotoKrete’s vision for the future, we invite you to listen to the full interview conducted by Eva Caballero on La mecánica del caracol.

▶ Listen to the full interview on Radio Euskadi: https://guau.eus/m/radio-euskadi-ciencia-tecnologia-e-historia-20260702-2105