On the Solar Reflectance Angular Dependence of Opaque Construction Materials and Impact on the Energy Balance of Building Components

Carnielo, Emiliano; Zinzi, Michele; Fanchiotti, Aldo

doi:10.1016/j.egypro.2014.02.141

Cited by 3 publications

(5 citation statements)

References 7 publications

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“…The solar reflectance of surfaces varies according to the angular distribution of the incident solar radiation, from a minimum value analogous to the normal incidence of a light beam to a maximum value corresponding to an incidence angle of 90º, depending on the surface roughness [58]. According to Fresnel equations, reflections in smooth surfaces are strictly dependent on the angle of incidence and have high angular reflectance values, while reflections from rough surfaces are less affected by incident angle variations [59].…”

Section: Angular Dependence Of the Solar Reflectancementioning

confidence: 99%

“…For instance, coatings for roof application usually present smooth surfaces. Thus, it is important to understand how the incident angle affects the solar reflectance in order to estimate the solar gains of building components [58]. Such estimation of solar gains of buildings should also include diffuse and specular reflections of the incident irradiation.…”

Section: Angular Dependence Of the Solar Reflectancementioning

confidence: 99%

“…Such estimation of solar gains of buildings should also include diffuse and specular reflections of the incident irradiation. Usually, solar gains can be determined using [58]:…”

Section: Angular Dependence Of the Solar Reflectancementioning

confidence: 99%

“…Specular reflection As such, Carnielo et al [58] considered two different reflectance components. The first is an angular component (𝜌 𝜃 ) related with the variation of the solar beam irradiance with the incidence angle (𝜃) that can be calculated from the interpolation of experimental values obtained at various 𝜃-values.…”

Section: Incident Lightmentioning

confidence: 99%

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Nanomaterials with high solar reflectance as an emerging path towards energy-efficient envelope systems: a review

et al. 2021

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The application of nanomaterials in the construction field is allowing the development of smart, green, durable and more efficient buildings. Among the most widely researched nanomaterials are nano-sized cool pigments, which are being enforced to achieve thermal and energy efficient façades, with the development of high reflectance and retroreflectance coatings. Their peculiar optical and catalytic activity turns nanomaterials into suitable candidates to be use as dark coloured high solar reflectance without affecting aesthetic characteristics, thus improving the durability of coatings. The objective of this paper is to review the state-of-the-art on the benefits of using high reflectance nano pigments as coatings in building façades and their production and synthesis processes. It is thus divided into three main topics: (i) the benefits of using nanopigments on façades, (ii) the most important nanomaterials used as cool pigments and (iii) the main methods of synthesising nanopigments. One expects that the study of near-infrared nanopigmentation synthesis processes will be able to promote and disseminate the use of nanotechnology in construction, assessing the production problems and limitation and thus helping to disseminate new products by reducing production costs and increase availability.

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Section: Angular Dependence Of the Solar Reflectancementioning

confidence: 99%

Section: Angular Dependence Of the Solar Reflectancementioning

confidence: 99%

“…Such estimation of solar gains of buildings should also include diffuse and specular reflections of the incident irradiation. Usually, solar gains can be determined using [58]:…”

Section: Angular Dependence Of the Solar Reflectancementioning

confidence: 99%

Section: Incident Lightmentioning

confidence: 99%

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Nanomaterials with high solar reflectance as an emerging path towards energy-efficient envelope systems: a review

et al. 2021

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“…For example, Liu (Liu and Geng 2004) applied the spectrophotometer to test the absorptivity of concrete directly and found that the absorptivity could be as low as 0.4. And then, Carnielo (Carnielo et al 2014) tested some conventional materials that could be used in buildings with the method of Integrating sphere. The results showed that the absorptivity would range from 0.5-0.6 for smooth light grey surfaces.…”

Section: Introductionmentioning

confidence: 99%

A novel model concerning the independence of emissivity and absorptivity for enhancing the sustainability of radiant cooling technology

Zhang

2022

Environ Sci Pollut Res

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A Novel Model Concerning the Independence of Emissivity and Absorptivity for Enhancing the Sustainability of Radiant Cooling Technology

Zhang

2021

Preprint

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Radiant cooling technology is a sustainable technology for improving built environment. The past research only studied the performance (e.g., radiant heat flux) based on Kirchhoff’s law while the accuracy and its reasons were seldom analyzed. In order to study the mechanism deeply, a new model of radiant heat transfer is derived theoretically which considers emissivity and absorptivity independently. This model is validated by the experimental data then applied in a reference case for further analysis. The analyzing methods of sensitivity and relative deviation are performed to investigate the reasons for the errors. The results of sensitivity analysis show that it is about 20% − 40% more sensitive for the emissivity to the heat flux than the absorptivity. Furthermore, the deviation of the heat flux can reach up to 20% when the absorptivity is in the range from 0.4 to 0.9. This deviation is close to the estimated error range of 21.8% in the past studies. Therefore, the discussion based on the theoretical analysis, shows that the errors in past studies are highly due to the oversimplified preconditions for applying Kirchhoff’s law and they ignored the impact of surface absorption. Additionally, the validation in the previous experiments was highly coincidence, since they neglected the key independent tests of the absorptivity and radiant heat flux. Comprehensively, the new model is valuable to provide a more reliable solution for analyzing the radiant heat transfer and for the future design of an independent test of radiant heat flux.

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On the Solar Reflectance Angular Dependence of Opaque Construction Materials and Impact on the Energy Balance of Building Components

Cited by 3 publications

References 7 publications

Nanomaterials with high solar reflectance as an emerging path towards energy-efficient envelope systems: a review

Nanomaterials with high solar reflectance as an emerging path towards energy-efficient envelope systems: a review

A novel model concerning the independence of emissivity and absorptivity for enhancing the sustainability of radiant cooling technology

A Novel Model Concerning the Independence of Emissivity and Absorptivity for Enhancing the Sustainability of Radiant Cooling Technology

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