Periodic Reporting for period 1 - COOLCRETE (Radiative COOLing conCRETE)
Período documentado: 2024-09-01 hasta 2025-08-31
Radiative cooling technology harnesses a unique natural phenomenon: the Earth’s ability to dissipate heat through the atmospheric transparency window (8–13 μm), also known as the Atmospheric Window (AW). This passive cooling mechanism enables terrestrial bodies to emit infrared radiation directly into outer space, thereby maintaining thermal balance without external energy input. The concept underpins a new generation of sustainable materials capable of counteracting the rising energy demand associated with air conditioning and refrigeration in modern cities.
Radiative cooling materials have gained widespread attention due to their versatility across multiple applications, including building envelopes, renewable energy systems, and dew water harvesting. Among these, their role in reducing building energy consumption is particularly critical, as the built environment currently accounts for over 40% of global energy demand, with cooling systems representing the largest share. In rapidly urbanizing regions such as East Asia, more than half of electricity consumption is devoted to maintaining indoor comfort. Therefore, the development of advanced, scalable, and cost-effective cooling materials could play a transformative role in global energy transition efforts.
Historically, “cool-roof” coatings based on polymer films with TiO2 pigments have offered moderate improvements, achieving solar reflectance values around 0.85 and high emissivity (≈0.95) within the AW. While these solutions can reduce surface temperatures by 20–30 °C, they remain limited in durability, scalability, and spectral control. More sophisticated photonic metamaterials and porous polymeric structures have emerged, yet these often rely on costly raw materials or energy-intensive fabrication processes.
Amid this technological landscape, the MIRACLE project introduced a breakthrough by integrating radiative cooling principles directly into cementitious materials. Through extensive multidisciplinary research, the project established the chemical and microstructural foundations for Daytime Radiative Cooling Cementitious Composites (DRCCCs)—a new class of concretes capable of operating below ambient temperature under direct sunlight. The COOLCRETE initiative now builds on this foundation, aiming to accelerate the path from laboratory discovery to commercial application.
The proposal pursues three key objectives:
- O1: Assess the integration of DRCCC technology with existing cooling systems, such as heat pumps and thermal energy storage devices.
- O2: Evaluate geoclimatic relevance, quantify energy performance, and assess environmental and economic impacts across regions and building types.
- O3: Identify target markets, potential clients, and commercialization routes, paving the way for the creation of a dedicated spin-off company by early 2025.
Radiative cooling materials have gained widespread attention due to their versatility across multiple applications, including building envelopes, renewable energy systems, and dew water harvesting. Among these, their role in reducing building energy consumption is particularly critical, as the built environment currently accounts for over 40% of global energy demand, with cooling systems representing the largest share. In rapidly urbanizing regions such as East Asia, more than half of electricity consumption is devoted to maintaining indoor comfort. Therefore, the development of advanced, scalable, and cost-effective cooling materials could play a transformative role in global energy transition efforts.
Historically, “cool-roof” coatings based on polymer films with TiO2 pigments have offered moderate improvements, achieving solar reflectance values around 0.85 and high emissivity (≈0.95) within the AW. While these solutions can reduce surface temperatures by 20–30 °C, they remain limited in durability, scalability, and spectral control. More sophisticated photonic metamaterials and porous polymeric structures have emerged, yet these often rely on costly raw materials or energy-intensive fabrication processes.
Amid this technological landscape, the MIRACLE project introduced a breakthrough by integrating radiative cooling principles directly into cementitious materials. Through extensive multidisciplinary research, the project established the chemical and microstructural foundations for Daytime Radiative Cooling Cementitious Composites (DRCCCs)—a new class of concretes capable of operating below ambient temperature under direct sunlight. The COOLCRETE initiative now builds on this foundation, aiming to accelerate the path from laboratory discovery to commercial application.
The proposal pursues three key objectives:
- O1: Assess the integration of DRCCC technology with existing cooling systems, such as heat pumps and thermal energy storage devices.
- O2: Evaluate geoclimatic relevance, quantify energy performance, and assess environmental and economic impacts across regions and building types.
- O3: Identify target markets, potential clients, and commercialization routes, paving the way for the creation of a dedicated spin-off company by early 2025.
WP1: Technological Readiness Level (TRL) Upgrade
The first work package explored the technical feasibility of coupling DRCCC surfaces with Hybrid Ground-Coupled Heat Pump (HGCHP) systems. A reference model using a Nocturnal Cooling Radiator (NCR) was redesigned into a Continuous Cooling Radiator (CCR) composed of DRCCC materials, enabling effective heat rejection both day and night. Simulations across Singapore, Brussels, and Phoenix revealed energy savings of up to 9.3% compared to traditional systems, alongside reductions in CO2 emissions ranging from 1.5 t to 12.2 t over ten years of operation.
To assess climatic performance, meteorological data and MODTRAN-based radiative transfer models were used to represent three representative climate types: humid tropical (Singapore), hot arid (Phoenix), and temperate oceanic (Brussels). Results demonstrated that COOLCRETE consistently maintains sub-ambient surface temperatures, even under intense solar exposure, while standard concretes exhibit overheating of up to 40 °C. Energy simulations for a three-floor office prototype confirmed substantial cooling energy reductions—up to 55 kWh/m² year—particularly in hot, dry climates. Though some heating penalties were observed in temperate regions during winter, these were offset by net annual energy savings and emissions reductions.
WP2: Business Readiness Level (BRL) Upgrade
The second work package analyzed the market integration potential of COOLCRETE through parametric building simulations and stakeholder feedback. The material’s performance was evaluated in relation to building typology, insulation level, and surface orientation. Results revealed that buildings with large roof-to-volume ratios, such as low-rise dwellings, experience the highest cooling benefits, while compact or highly insulated buildings exhibit lower sensitivity.
Orientation studies further highlighted that East–West pitched roofs offer optimal trade-offs between cooling efficiency and winter solar gains, while North–South roofs maximize cooling in hot climates. Extending COOLCRETE coatings to façades can amplify benefits but may increase heating demand in colder regions.
Stakeholder consultations, conducted with EU and U.S. experts, confirmed growing demand for sustainable concrete solutions amid tightening regulations and increasing concern over the urban heat island (UHI) effect. Experts also identified regulatory fragmentation as a key barrier, underscoring the need for European-level standardization to accelerate market adoption.
The first work package explored the technical feasibility of coupling DRCCC surfaces with Hybrid Ground-Coupled Heat Pump (HGCHP) systems. A reference model using a Nocturnal Cooling Radiator (NCR) was redesigned into a Continuous Cooling Radiator (CCR) composed of DRCCC materials, enabling effective heat rejection both day and night. Simulations across Singapore, Brussels, and Phoenix revealed energy savings of up to 9.3% compared to traditional systems, alongside reductions in CO2 emissions ranging from 1.5 t to 12.2 t over ten years of operation.
To assess climatic performance, meteorological data and MODTRAN-based radiative transfer models were used to represent three representative climate types: humid tropical (Singapore), hot arid (Phoenix), and temperate oceanic (Brussels). Results demonstrated that COOLCRETE consistently maintains sub-ambient surface temperatures, even under intense solar exposure, while standard concretes exhibit overheating of up to 40 °C. Energy simulations for a three-floor office prototype confirmed substantial cooling energy reductions—up to 55 kWh/m² year—particularly in hot, dry climates. Though some heating penalties were observed in temperate regions during winter, these were offset by net annual energy savings and emissions reductions.
WP2: Business Readiness Level (BRL) Upgrade
The second work package analyzed the market integration potential of COOLCRETE through parametric building simulations and stakeholder feedback. The material’s performance was evaluated in relation to building typology, insulation level, and surface orientation. Results revealed that buildings with large roof-to-volume ratios, such as low-rise dwellings, experience the highest cooling benefits, while compact or highly insulated buildings exhibit lower sensitivity.
Orientation studies further highlighted that East–West pitched roofs offer optimal trade-offs between cooling efficiency and winter solar gains, while North–South roofs maximize cooling in hot climates. Extending COOLCRETE coatings to façades can amplify benefits but may increase heating demand in colder regions.
Stakeholder consultations, conducted with EU and U.S. experts, confirmed growing demand for sustainable concrete solutions amid tightening regulations and increasing concern over the urban heat island (UHI) effect. Experts also identified regulatory fragmentation as a key barrier, underscoring the need for European-level standardization to accelerate market adoption.
The outcomes of MIRACLE and COOLCRETE demonstrate that radiative cooling concretes could redefine sustainable construction by merging thermal functionality, durability, and scalability. In warm climates, conventional concrete surfaces can exceed 60 °C under sunlight, whereas DRCCCs maintain temperatures below 30 °C, enabling passive energy savings of up to 50 kWh/m² annually. This translates into tangible economic and environmental benefits, particularly when scaled to urban infrastructure.
Beyond individual buildings, the adoption of DRCCC materials could significantly mitigate the UHI effect, which currently increases urban temperatures by up to 12 °C compared to rural surroundings. Increasing surface albedo from 0.2 to 0.9 could generate a localized cool-island effect, lowering ambient air temperature by approximately 1.5–1.6 °C. Given that cement-based materials dominate urban surfaces, their transformation into radiative coolers presents a scalable and cost-effective climate adaptation strategy.
Moreover, the technology exhibits strong synergy with heat pumps and thermal storage systems, enabling continuous operation throughout the day and improving system-level efficiency. Economic analyses predict up to 5.3% cost savings compared with conventional heat pumps, demonstrating clear commercial viability.
Finally, life-cycle assessments confirm that DRCCCs outperform existing radiative materials in sustainability metrics.
Beyond individual buildings, the adoption of DRCCC materials could significantly mitigate the UHI effect, which currently increases urban temperatures by up to 12 °C compared to rural surroundings. Increasing surface albedo from 0.2 to 0.9 could generate a localized cool-island effect, lowering ambient air temperature by approximately 1.5–1.6 °C. Given that cement-based materials dominate urban surfaces, their transformation into radiative coolers presents a scalable and cost-effective climate adaptation strategy.
Moreover, the technology exhibits strong synergy with heat pumps and thermal storage systems, enabling continuous operation throughout the day and improving system-level efficiency. Economic analyses predict up to 5.3% cost savings compared with conventional heat pumps, demonstrating clear commercial viability.
Finally, life-cycle assessments confirm that DRCCCs outperform existing radiative materials in sustainability metrics.