Transparent energy-saving windows based on broadband directional thermal emission
Minyeol Bae1, Do Hyeon Kim1, Sun-Kyung Kim2
1School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology (GIST), Cheomdangwagi-ro 123, Buk-gu, Gwangju 61005, Republic of Korea.
Nanophotonics (Berlin, Germany)
|December 5, 2024
Summary
This study introduces directional radiative cooling glass (DRCG) for sustainable building cooling. The new glass enhances energy efficiency by enabling passive radiative cooling even on vertical surfaces, reducing temperatures by over 1.5°C.
Area of Science:
- Materials Science
- Sustainable Energy
- Optics
Background:
- Passive radiative cooling offers energy-free, emission-free sustainable solutions.
- Conventional radiative coolers require skyward orientation, limiting vertical surface application.
- Urban heat island effect necessitates innovative cooling technologies.
Purpose of the Study:
- To develop a directional radiative cooling glass (DRCG) for efficient heat dissipation from vertical surfaces.
- To overcome the limitations of conventional radiative coolers in obstructed environments.
- To enhance building energy efficiency and mitigate urban heat island effects.
Main Methods:
- Fabrication of DRCG using a multilayer structure with epsilon-near-zero materials (Si3N4 and Al2O3) on an indium-tin-oxide thermal reflector.
- Utilizing angular selective emission (Berreman mode) for directional heat dissipation.
- Conducting theoretical simulations and outdoor experiments to evaluate cooling performance and visible transmittance.
Main Results:
- DRCG exhibits angular selective emission, restricting thermal emission to specific angles.
- Visible transmittance of the DRCG exceeds 84%.
- Simulations and experiments show over 1.5°C temperature reduction compared to conventional glass in simulated urban environments.
- DRCG windows enhanced space-cooling performance by approximately 1.5°C in outdoor tests.
Conclusions:
- DRCG offers an effective solution for passive radiative cooling on vertical surfaces.
- The technology demonstrates significant potential for energy-saving windows.
- DRCG can contribute to mitigating the urban heat island effect through enhanced building cooling.
More Related Videos
Related Concept Videos
01:20Conduction, Convection and Radiation: Problem Solving
1.2K
There are three methods by which heat transfer can take place: conduction, convection, and radiation. Each method has unique and interesting characteristics, but all three have two things in common: they transfer heat solely because of a temperature difference; and the greater the temperature difference, the faster the heat transfer.
In order to solve a problem related to heat transfer, first of all, the situation needs to be examined to determine the type of heat transfer involved. This could...
In order to solve a problem related to heat transfer, first of all, the situation needs to be examined to determine the type of heat transfer involved. This could...
1.2K
01:17Radiation: Applications
1.1K
The average temperature of Earth is the subject of much current discussion. Earth is in radiative contact with both the Sun and dark space; it receives almost all its energy from the radiation of the Sun and reflects some of it into outer space. Dark space is very cold, about 3 K, so Earth radiates energy into it. For instance, heat transfer occurs from soil and grasses, the rate of which can be so rapid that frost can occur on clear summer evenings, even in warm latitudes.
The average...
The average...
1.1K
01:05Absorption of Radiation
706
The rate of heat transfer by emitted radiation is described by the Stefan-Boltzmann law of radiation:
706