Periodic Reporting for period 3 - MIRACLE (Photonic Metaconcrete with Infrared RAdiative Cooling capacity for Large Energy savings)
Periodo di rendicontazione: 2024-02-01 al 2025-01-31
The MIRACLE project aimed to construct and test a revolutionary Photonic Meta-Concrete (PMC) whose response to light is engineered for exhibiting radiative cooling ability; i.e. the PMC will be able to expel heat from buildings to the outer space without any extra energy consumption.
For this to happen, the photonic properties must be engineered for efficiently scattering sun-light while focusing the emissivity in the Atmospheric Window (a narrow spectral region centred at light wavelengths of 10 microns where the atmosphere is transparent). To this end, MIRACLE project is revisiting the concept of concrete at a threefold level.
• The most appropriated chemical ingredients must be chosen in view of their photonic response.
• The hierarchical porous cementitious structure must be carefully tuned to enhance the light scattering.
• The inclusion of microstructures in a regular or random fashion so as to truly form a PMC with radiative cooling performance.
In the context of an increasing global warming this scientific and technologic breakthrough can have a huge impact in the Nearly-Zero-Energy-Buildings (NZEB) uptake and in the global strategy for reducing the CO2 footprint.
Overall, the MIRACLE project endeavours to
(1) prove the feasibility of this breakthrough idea by developing for the first time in the state of the art a radiative cooling device based on a PMC,
(2) fabricate a prototype whose radiative cooling performance will be validated on the roof of a real building and
(3) start the roadmap of this emerging S&T avenue (PMC) by evaluating its potential environmental impact and exploring how the PMCs could be used in other applications.
For this to happen, the photonic properties must be engineered for efficiently scattering sun-light while focusing the emissivity in the Atmospheric Window (a narrow spectral region centred at light wavelengths of 10 microns where the atmosphere is transparent). To this end, MIRACLE project is revisiting the concept of concrete at a threefold level.
• The most appropriated chemical ingredients must be chosen in view of their photonic response.
• The hierarchical porous cementitious structure must be carefully tuned to enhance the light scattering.
• The inclusion of microstructures in a regular or random fashion so as to truly form a PMC with radiative cooling performance.
In the context of an increasing global warming this scientific and technologic breakthrough can have a huge impact in the Nearly-Zero-Energy-Buildings (NZEB) uptake and in the global strategy for reducing the CO2 footprint.
Overall, the MIRACLE project endeavours to
(1) prove the feasibility of this breakthrough idea by developing for the first time in the state of the art a radiative cooling device based on a PMC,
(2) fabricate a prototype whose radiative cooling performance will be validated on the roof of a real building and
(3) start the roadmap of this emerging S&T avenue (PMC) by evaluating its potential environmental impact and exploring how the PMCs could be used in other applications.
The results of the MIRACLE project have been highly encouraging. We conducted a comprehensive study combining simulations and experiments, enabling an in-depth analysis of the photonic response of various phases found in cementitious composites. Unlike the limited existing work on 3D concrete materials—mostly focused on conventional formulations—our research has shown that typical concrete compositions can be drastically optimized for radiative cooling.
We have developed several concrete designs capable of daytime radiative cooling; these prototypes consistently maintained temperatures significantly below ambient levels, even under direct sunlight on hot summer days. Photonic performance was on par with the best state-of-the-art cooling materials. These results were validated through extended outdoor experiments on the roof of the KUBIK building, where our materials outperformed both standard concretes and those coated with commercial cool paints. Moreover, MIRACLE concretes exhibit these remarkable radiative cooling properties while maintaining a very low environmental impact, as demonstrated in a benchmarking study comparing their life-cycle assessment (LCA) with other leading radiative cooling solutions.
In addition, we evaluated the environmental impact of our PMCs. Notably:
We demonstrated that our PCMs can lead to substantial energy savings in buildings—up to 70% in cooling energy for a typical mid-rise building, depending on the climate.
Our models predict that using our PCMs could significantly mitigate the Urban Heat Island Effect, with potential city-wide temperature reductions of up to 10°C during heatwaves.
Furthermore, our studies revealed that integrating our PCMs can lower the operating temperature of solar cells by as much as 20 K, resulting in enhanced efficiency and lifespan.
The intense research effort has yielded numerous scientific publications—35 accepted to date, with more forthcoming. MIRACLE’s impact has also been recognized internationally with a couple of conference awards.
We have also organized two international workshops, which served as valuable platforms to present our progress and engage with key stakeholders including scientists, industry professionals, and policymakers.
Finally, we’ve placed a strong emphasis on translating our research into practical, market-ready solutions. In addition to participating in numerous industrial fairs, we have secured two patents for our most promising technologies. To support commercialization, we launched a spin-off company, PhotoKrete S.L. which aims to accelerate the deployment of our patented PCMs.
We have developed several concrete designs capable of daytime radiative cooling; these prototypes consistently maintained temperatures significantly below ambient levels, even under direct sunlight on hot summer days. Photonic performance was on par with the best state-of-the-art cooling materials. These results were validated through extended outdoor experiments on the roof of the KUBIK building, where our materials outperformed both standard concretes and those coated with commercial cool paints. Moreover, MIRACLE concretes exhibit these remarkable radiative cooling properties while maintaining a very low environmental impact, as demonstrated in a benchmarking study comparing their life-cycle assessment (LCA) with other leading radiative cooling solutions.
In addition, we evaluated the environmental impact of our PMCs. Notably:
We demonstrated that our PCMs can lead to substantial energy savings in buildings—up to 70% in cooling energy for a typical mid-rise building, depending on the climate.
Our models predict that using our PCMs could significantly mitigate the Urban Heat Island Effect, with potential city-wide temperature reductions of up to 10°C during heatwaves.
Furthermore, our studies revealed that integrating our PCMs can lower the operating temperature of solar cells by as much as 20 K, resulting in enhanced efficiency and lifespan.
The intense research effort has yielded numerous scientific publications—35 accepted to date, with more forthcoming. MIRACLE’s impact has also been recognized internationally with a couple of conference awards.
We have also organized two international workshops, which served as valuable platforms to present our progress and engage with key stakeholders including scientists, industry professionals, and policymakers.
Finally, we’ve placed a strong emphasis on translating our research into practical, market-ready solutions. In addition to participating in numerous industrial fairs, we have secured two patents for our most promising technologies. To support commercialization, we launched a spin-off company, PhotoKrete S.L. which aims to accelerate the deployment of our patented PCMs.
So far, radiative cooling technology has attracted wide interest from both fundamental and applied sciences, due to its potential in applications like building cooling, renewable energy harvesting, or dew water production. However, its development currently faces a bottleneck: scientific progress has largely relied on either (i) intricate 1D and 2D photonic metamaterials made with scarce and expensive materials, offering little real-world potential; or (ii) hierarchically porous polymer coatings, which are scalable but costly to produce, lack spectral selectivity, and suffer from durability issues such as UV degradation.
In this context, the MIRACLE project explored the idea of transforming cement-based materials into “ultimate composites” for radiative cooling. We hypothesized that properly tuned concrete could merge the advantages of photonic metamaterials and porous systems.
The project confirmed this vision: for the first time, we successfully fabricated a low-cost, scalable radiative cooling device based on concrete that operates at subambient temperatures under direct sunlight.
The PCMs developed in MIRACLE have the potential to revolutionize both buildings and urban environments.
a) Exceptional Potential for Building Energy Savings
Our patented PCMs offer a strong alternative for reducing cooling energy demand. They dissipate heat via infrared radiation with high efficiency, staying below ambient temperature—even in full sun.
b) Scalability and Cost-Competitiveness
Built on standard concrete technologies, our solution integrates easily into the construction industry. Using common materials, it remains cost-competitive—unlike many radiative cooling materials that require rare or expensive components and complex manufacturing.
c) Sustainability and Global Environmental Impact
Our environmental analysis revealed that existing solutions often rely on metals and energy-intensive deposition methods. MIRACLE concretes avoid these, using sustainable materials and processes with low environmental impact.
d) Combatting the Urban Heat Island (UHI) Effect
Given the prevalence of cement in cities, MIRACLE PCMs are ideally suited to mitigate UHI. In heatwave conditions (day ~40 °C, night ~30 °C), they can reduce surface temps by up to 10 °C by day and 5 °C by night—greatly enhancing urban resilience.
In this context, the MIRACLE project explored the idea of transforming cement-based materials into “ultimate composites” for radiative cooling. We hypothesized that properly tuned concrete could merge the advantages of photonic metamaterials and porous systems.
The project confirmed this vision: for the first time, we successfully fabricated a low-cost, scalable radiative cooling device based on concrete that operates at subambient temperatures under direct sunlight.
The PCMs developed in MIRACLE have the potential to revolutionize both buildings and urban environments.
a) Exceptional Potential for Building Energy Savings
Our patented PCMs offer a strong alternative for reducing cooling energy demand. They dissipate heat via infrared radiation with high efficiency, staying below ambient temperature—even in full sun.
b) Scalability and Cost-Competitiveness
Built on standard concrete technologies, our solution integrates easily into the construction industry. Using common materials, it remains cost-competitive—unlike many radiative cooling materials that require rare or expensive components and complex manufacturing.
c) Sustainability and Global Environmental Impact
Our environmental analysis revealed that existing solutions often rely on metals and energy-intensive deposition methods. MIRACLE concretes avoid these, using sustainable materials and processes with low environmental impact.
d) Combatting the Urban Heat Island (UHI) Effect
Given the prevalence of cement in cities, MIRACLE PCMs are ideally suited to mitigate UHI. In heatwave conditions (day ~40 °C, night ~30 °C), they can reduce surface temps by up to 10 °C by day and 5 °C by night—greatly enhancing urban resilience.