Graduation Year

2022

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Civil and Environmental Engineering

Major Professor

Austin Gray Mullins, Ph.D.

Committee Member

Elias Stefanakos, Ph.D.

Committee Member

Abla Zayed, Ph.D.

Committee Member

Michael J. Stokes, Ph.D.

Committee Member

Joseph Smoak, Ph.D.

Keywords

Cool Roof Coating, Doped Zinc Oxide Semiconductor Nanocrystals, Geoengineering, Global Warming, Nanocrystals, Passive Daytime Cooling

Abstract

Passive cooling of buildings is a benefit to society since no energy input is required for space cooling which reduces electricity consumption, fossil fuel burning, and greenhouse gas emissions. When a passive cooling technology radiates heat from the earth through the atmospheric windows to space higher levels of cooling power are possible -- this phenomenon is classified as passive “radiative” cooling. Spectrally selective surface coatings provide radiative cooling to lower surface temperatures by reflecting most solar radiation, while emitting infrared radiation at wavelengths between 8-13 μm through the primary atmospheric window to the cold of space. Multiple applications of radiative cooling can be of benefit to the modern world like radiating surfaces to reduce the “heat island” effect from heat absorbing materials amassed in large cities. Additionally, it is estimated that covering over 10 million square kilometers with a cooling power of 100 W/m2 it may be theoretically possible to balance the heat flux between the earth and space to counter global warming by emitting more infrared radiation from the earth. The goal of this research is to develop a practical, cost effective, scalable, and robust passive radiative cooling coating for ease of application to a multitude of surfaces like cool roof coating yet provide greater cooling power and energy savings, as well as alter cooling power for buildings in colder climates to avoid costly heating load increases in colder climatic conditions. Presented is a novel approach to synthesizing nanoparticles with close to ideal spectrally selective for passive radiative cooling to be integrated into thick film nanocomposite coating which can cost effectively cover large surface areas.

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