Analysis of Sustainable Materials for Radiative Cooling Potential of Building Surfaces

Abstract

The main goal of this paper is to explore the radiative cooling and solar heating potential of several materials for the built environment, based on their spectrally-selective properties. A material for solar heating, should have high spectral emissivity/absorptivity in the solar radiation band (within the wavelength range of 0.2–2 μm), and low emissivity/absorptivity at longer wavelengths. Radiative cooling applications require high spectral emissivity/absorptivity, within the atmospheric window band (8–13 μm), and a low emissivity/absorptivity in other bands. UV-Vis spectrophotometer and FTIR spectroscopy, are used to measure, the spectral absorption/emission spectra of six different types of materials. To evaluate the radiative cooling potential of the samples, the power of cooling is calculated. Heat transfer through most materials is not just a surface phenomenon, but it also needs a volumetric analysis. Therefore, a coupled radiation and conduction heat transfer analysis is used. Results are discussed for the selection of the best materials, for different applications on building surfaces.

Sensitivity of Radiative and Thermal Properties of Building Material in the Urban Atmosphere

“…The emissivity has a fundamental role in the quantity of longwave radiation emitted by a surface. Its high value tends to reduce the temperature intensity during the day [76][77][78], because this surface emits thermal radiation.…”

Characterization and Optimization of AZO Nanoparticles as Coatings for Flexible Substrates toward High IR Reflectivity

“…In 2010, the European Union (EU) has agreed to reduce the energy consumption of buildings by 20% in 2020 and up to 50% by 2050 . One promising approach to reduce energy consumption by heating and cooling of buildings is the use of materials with low thermal emissivity (low-e) as a coating in architecture for passive radiative cooling applications. − Low-e materials reflect thermal radiation, mainly in the near-, midwave-, and infrared (NIR, MIR, IR) fields without absorbing or transmitting radiative heat. A low-e coating therefore allows reducing heat transfer, e.g., between the inside and outside of buildings. − Common industrially processed materials fulfilling these needs are transparent conductive oxides (TCO) .…”

“…One promising approach to reduce energy consumption by heating and cooling of buildings is the use of materials with low thermal emissivity (low-e) as a coating in architecture for passive radiative cooling applications. − Low-e materials reflect thermal radiation, mainly in the near-, midwave-, and infrared (NIR, MIR, IR) fields without absorbing or transmitting radiative heat. A low-e coating therefore allows reducing heat transfer, e.g., between the inside and outside of buildings. − Common industrially processed materials fulfilling these needs are transparent conductive oxides (TCO) . TCO are widely used as low-e coatings of building materials including windows, as they exhibit high reflectivity in the IR spectral range combined with high transparency in the visible field. , TCO coatings are mainly synthesized and deposited on rigid substrates like glass directly by sputtering techniques .…”