# US 11,306,949 B2 · Systems and methods for radiative cooling and heating

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- Number: US 11,306,949 B2
- Document ID: US11306949B2
- Status: Granted
- Kind: B2
- Application number: 16/451,807
- Filed: 2019-06-25
- Published: 2020-01-23
- Granted: 2022-04-19
- Earliest claimed: 2015-06-18
- Assignees: The Trustees of Columbia University in the City of New York
- Applicants: The Trustees of Columbia University In the City of New York
- Inventors: Nanfang Yu; Jyotirmoy Mandal; Adam Overvig; Norman Nan Shi; Meng Tian
- Web page: https://patentgrep.com/patent/US11306949B2

## CPC

- F25B 23/003: {using selective radiation effect}
- B32B 27/18: characterised by the use of special additives
- B32B 27/283: {comprising polysiloxanes}
- B32B 33/00: Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
- F24S 70/225: for spectrally selective absorption
- F24S 70/30: Auxiliary coatings, e.g. anti-reflective coatings
- F24S 70/60: characterised by the structure or construction (absorbing coatings or surface treatment for increasing absorption F24S70/20; auxiliary coatings F24S70/30)
- F28F 13/18: by applying coatings, e.g. radiation-absorbing, radiation-reflecting; by surface treatment, e.g. polishing
- B32B 2305/18: Fabrics, textiles
- B32B 2305/30: Fillers, e.g. particles, powders, beads, flakes, spheres, chips
- B32B 2307/30: having particular thermal properties
- B32B 2307/416: Reflective
- B32B 2311/24: Aluminium
- B32B 2333/12: Polymers of methacrylic acid esters, e.g. PMMA, i.e. polymethylmethacrylate
- B32B 2383/00: Polysiloxanes
- B32B 2386/00: Specific polymers obtained by polycondensation or polyaddition not provided for in a single one of index codes B32B2363/00 - B32B2383/00
- F24S 10/40: in absorbing elements surrounded by transparent enclosures, e.g. evacuated solar collectors
- F28F 2245/06: having particular radiating, reflecting or absorbing features, e.g. for improving heat transfer by radiation
- Y02E 10/44: Heat exchange systems
- F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- F24S: SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS (for producing mechanical power from solar energy F03G6/00)
- F28F: DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION (water and air traps, air venting F16)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Systems and methods for radiative cooling and heating are provided. For example, systems for radiative cooling can include a top layer including one or more polymers, where the top layer has high emissivity in at least a portion of the thermal spectrum and an electromagnetic extinction coefficient of approximately zero, absorptivity of approximately zero, and high transmittance in at least a portion of the solar spectrum, and further include a reflective layer including one or more metals, where the reflective layer has high reflectivity in at least a portion of the solar spectrum.

## Claims

### Claim 1

A system for radiative heating, comprising:
a top layer comprising one or more structured materials and having high absorptivity in at least a portion of the solar spectrum; and
an underlying layer having a lower refractive index than a refractive index of the top layer in at least a portion of the thermal spectrum, wherein the underlying layer comprises at least one air void and is configured to create at least one Mie resonance throughout the solar and/or thermal spectrum.

### Claim 2 (depends on 1)

The system of claim 1, wherein the top layer comprises silicon, gallium arsenide, and/or germanium.

### Claim 3 (depends on 1)

The system of claim 1, wherein the underlying layer comprises one or more of silicon dioxide, calcium fluoride, magnesium fluoride, and/or poly(dimethyl siloxane.

### Claim 4 (depends on 1)

The system of claim 1, wherein the top layer comprises one or more regions comprising one or more arrays including one or more ridges and/or protrusions.

### Claim 5

A method for radiative heating, comprising:
providing a top layer comprising one or more structured materials and having high absorptivity in at least a portion of the solar spectrum and emissivity of less than about 0.1 in at least a portion of the thermal spectrum; and
providing an underlying layer having a lower refractive index than a refractive index of the top layer in at least a portion of the thermal spectrum, wherein the underlying layer comprises at least one air void and is configured to create at least one Mie resonance throughout the solar and/or thermal spectrum.