Building coatings can achieve 7°C subambient cooling without electricity.

Why It Matters

This research offers a pathway to drastically reduce the energy consumption of buildings by leveraging passive cooling strategies. Designers can explore integrating such advanced coatings into building envelopes to enhance thermal comfort and lower operational costs, contributing to more sustainable built environments.

Key Finding

A new type of building coating can cool surfaces significantly below the ambient air temperature during the day, using only natural radiative cooling principles, without needing electricity or complex manufacturing.

Key Findings

• The upgraded coating achieved a temperature 6 °C below ambient on an aluminum plate and 7 °C below ambient on a scale-model building under direct sunlight.
• The cooling power achieved was 84.2 W m⁻².
• The method eliminates the need for resonant microstructures and noble metal mirrors typically found in subambient radiative cooling systems.

Research Evidence

Aim: How can conventional building coatings be modified to achieve subambient radiative cooling effects without requiring complex microstructures or active energy input?

Method: Experimental investigation and theoretical proof

Procedure: The researchers developed a generic method to upgrade conventional building coatings by incorporating particle scattering, sunlight-excited fluorescence, and mid-infrared broadband radiation. They theoretically proved that heat exchange with the sky can eliminate the need for resonant microstructures and noble metal mirrors, leading to enhanced daytime cooling. The performance of the upgraded coating was then tested on an aluminum plate and a scale-model building under direct sunlight.

Context: Building materials and passive cooling technologies

Design Principle

Leverage radiative cooling to achieve passive thermal regulation in built environments.

How to Apply

Consider using coatings with enhanced radiative properties on building exteriors, roofs, and facades to reduce heat gain and cooling loads.

Limitations

Performance may vary with atmospheric conditions (e.g., humidity, cloud cover) and specific coating formulations. Long-term durability and cost-effectiveness for large-scale deployment require further investigation.

Student Guide (IB Design Technology)

Simple Explanation: Scientists have created a special paint for buildings that can make them cooler than the outside air, even when the sun is shining, without using any electricity.

Why This Matters: This research shows how to make buildings more energy-efficient and comfortable by using smart materials that cool themselves down naturally, which is important for designing sustainable structures.

Critical Thinking: To what extent can this passive cooling technology be scaled up for widespread adoption in diverse climatic conditions, and what are the primary economic and logistical challenges?

IA-Ready Paragraph: This research demonstrates a significant advancement in passive cooling technology for buildings, where a novel coating achieved a temperature reduction of up to 7°C below ambient through integrated radiative cooling mechanisms. This approach offers a sustainable and energy-efficient alternative to conventional cooling systems, highlighting the potential for material innovation in reducing the environmental impact of the built environment.

Project Tips

• Investigate materials that naturally reflect sunlight and emit heat effectively.
• Explore how different surface textures or embedded particles can enhance radiative cooling properties.

How to Use in IA

• Reference this study when exploring passive cooling strategies for building design projects.
• Use the findings to justify the selection of materials that minimize heat absorption and maximize heat dissipation.

Examiner Tips

• Demonstrate an understanding of how passive cooling mechanisms can be integrated into design solutions.
• Discuss the potential impact of such technologies on energy consumption and environmental sustainability.

Independent Variable: Coating composition and properties (particle scattering, fluorescence, IR radiation)

Dependent Variable: Temperature difference below ambient, cooling power

Controlled Variables: Solar intensity, ambient temperature, wind speed, material substrate

Strengths

• Demonstrates a novel, practical method for enhancing radiative cooling in building materials.
• Provides both experimental results and theoretical validation.

Critical Questions

• How does the long-term durability of this coating compare to traditional building materials?
• What are the potential environmental impacts of the materials used in the coating itself?

Extended Essay Application

• Investigate the potential for integrating advanced radiative cooling materials into architectural designs to reduce a building's carbon footprint.
• Analyze the economic feasibility and market adoption challenges of such innovative building materials.

Source

Creating an Eco‐Friendly Building Coating with Smart Subambient Radiative Cooling · Advanced Materials · 2020 · 10.1002/adma.201906751