A novel technique for the production of cool colored concrete tile and asphalt shingle roofing products

Levinson, Ronnen; Akbari, Hashem; Berdahl, Paul; Wood, Kurt A.; Skilton, Wayne; Petersheim, Jerry

doi:10.1016/j.solmat.2009.12.012

Cited by 144 publications

(64 citation statements)

References 12 publications

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“…For instance, cobalt aluminate (absorption coefficient, K ~150 mm 1 , backscattering coefficient, S ~30 mm 1 ) has been reported to have undesirable absorption and weak NIR scattering in the 1200-1600 nm range [6]. To obtain cool coating features, cobalt aluminate needs to be coated on NIR reflective substrates such as white, which makes the color lighter [1]. Further, such white backgrounds are rarely observed in the case of roof surfaces, leather etc.…”

Section: Resultsmentioning

confidence: 99%

“…Polytetrfluoroethylene (PTFE) was used as the reference. NIR solar reflectance (R * ) was calculated in accordance with ASTM standard E891-87 [1,4,17]. Solar reflectance or fraction of solar radiation incident at wavelengths between 700-2500 nm is the irradiance weighted average of spectral reflectance, r (), determined as 2500 * 700…”

Section: Characterizationmentioning

confidence: 99%

“…With applications in military, construction, plastic, leather and ink industries, near infra-red reflective non-white pigments are becoming more and more relevant [1][2][3][4][5]. They are expected to reflect almost 49% of near-infrared radiation from the sun (=750-2500 nm) and thus reduce energy requirements for cooling of interiors of buildings, automobiles, etc [6].…”

Section: Introductionmentioning

confidence: 99%

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Rare earth doped cobalt aluminate blue as an environmentally benign colorant

2012

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Increasing energy cost calls for exterior coatings with high near infra-red reflectance, so as to reduce heat absorption and in turn cost of air-conditioning. While modulations of substrate, use of white metal oxides as pigments or under-layers has been reported in past, reports on metal oxide or doped metal oxide pigments with high NIR reflectance is scarce. We report for the first time a blue colored cobalt aluminate type pigment prepared through doping of cerium, praseodymium or neodymium. CIELAB color measurements and calculation of E indicated that the Nd doped sample had crystal size of (36±1) nm, bandgap value of (2.4±0.2) eV and color coordinates similar to that of cobalt aluminate. The molar ratio as estimated by EDX was found to be Al : Cu : Co : Ce : Nd : O= 2 : 0.06 : 0.06 : 0.012 : 0.000 12 : 6.18. The pigment was found to have potential applications as a cool blue colorant, owing to changes in optical properties arising out of crystal chemistry changes. Incorporation of rare earth metal ions was found to enhance the NIR reflectance by 10%, when compared to a conventional cobalt aluminate pigment. The oxide has been well characterized and its performance as a pigment evaluated. We have proposed that changes in crystal lattice when neodymium enters into Ce 4+ sites enhance the NIR reflectance by about 9% as against the entry of praseodymium.

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Section: Resultsmentioning

confidence: 99%

Section: Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Rare earth doped cobalt aluminate blue as an environmentally benign colorant

2012

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“…One of the most noticeable aspects related to the use of a cool paint on the finishing layer of a roof is the sharp reduction of its outer surface temperature; according to several case studies [29][30][31], a mean reduction of 12 ∘ C is expected when using a product with average quality ( = 0.45), whereas the use of a high-reflective paint ( = 0.85) can introduce a temperature reduction up to 25 ∘ C. As concerns this case study, Figure 5 shows that the outer surface temperature for the existing roof is always higher than that reached by the painted roof. The minimum difference pertains to the less performing paint ( = 0.45) and ranges around 5-10 ∘ C, but in the case of the best performing paint such temperature difference actually increases up to [20][21][22][23][24][25][26][27][28][29][30] ∘ C. Furthermore, as shown in Figure 6 for the hottest days of the year, the use of a cool paint on the roof leads to a sensible reduction of the peak outer surface temperature while at night this difference is more limited.…”

Section: Roof Temperaturementioning

confidence: 99%

Study on the Application of Cool Paintings for the Passive Cooling of Existing Buildings in Mediterranean Climates

Costanzo

Evola

Gagliano

et al. 2013

Advances in Mechanical Engineering

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Building roofs play a very important role in the energy balance of buildings, especially in summer, when they are hit by a rather high solar irradiance. Depending on the type of finishing layer, roofs can absorb a great amount of heat and reach quite high temperatures on their outermost surface, which determines significant room overheating. However, the use of highly reflectivecool materials can help to maintain low outer surface temperatures; this practice may improve indoor thermal comfort and reduce the cooling energy need during the hot season. This technology is currently well known and widely used in the USA, while receiving increasing attention in Europe. In order to investigate the effectiveness of cool roofs as a passive strategy for passive cooling in moderately hot climates, this paper presents the numerical results of a case study based on the dynamic thermal analysis of an existing office building in Catania (southern Italy, Mediterranean area). The results show how the application of a cool paint on the roof can enhance the thermal comfort of the occupants by reducing the operative temperatures of the rooms and to reduce the overall energy needs of the building for space heating and cooling.

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“…In fact, "traditional" cool materials are traditionally light-colored, in order to optimize their reflectance in the visible part (Vis) of the solar spectrum, while cool-colored materials are optimized in the infrared part of the spectrum (IR), which is not visible to the human eye. Therefore, cool-colored materials improve thermal-optic characteristics, and go beyond the reduced variety of colors of traditional cool materials [34][35][36][37][38][39][40][41].…”

Section: Introductionmentioning

confidence: 99%

On Innovative Cool-Colored Materials for Building Envelopes: Balancing the Architectural Appearance and the Thermal-Energy Performance in Historical Districts

et al. 2017

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Architectural expression and energy performance are key decision-drivers in the selection of a particular construction element, with the purpose of Urban Heat Island mitigation, energy-consumption reductions, and cultural heritage preservation in historical centers. In historical centers, the external layer of the envelope and the visible parts of the building are built with traditional materials and technological solutions, such as single-layer walls or brickworks, depending on the country's context, while the energy performance is usually optimized by means of internal insulation layers, or other active and passive solutions. Thermal-energy efficient materials and construction elements for the temperate, warm climate of the Mediterranean area are usually light-colored to reflect the largest part of solar radiation, thus reducing energy demands for cooling and improving thermal comfort conditions for occupants. On the other hand, many historical centers in such areas are characterized by reddish or grayish colors. In this work, we considered Italian historical areas, and other countries in the Mediterranean area with present similar situations. Thus, in this study, innovative, cool-colored, cement-based materials were developed to improve the thermal-energy performance of the external envelope of historical/historic built environments, without altering their appearance. These materials were prepared directly on-site, by mixing two types of pigments to achieve the desired color saturation. Optic and thermal properties were assessed, and yearly dynamic simulations of a historic, listed, case study building were performed, by comparing traditional-colored mortar and the prototype cool mortar envelopes. The research demonstrates that such cool-colored materials can maintain lower surface temperatures (−8 • C), while reducing energy demands for cooling (−3%).

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A novel technique for the production of cool colored concrete tile and asphalt shingle roofing products

Cited by 144 publications

References 12 publications

Rare earth doped cobalt aluminate blue as an environmentally benign colorant

Rare earth doped cobalt aluminate blue as an environmentally benign colorant

Study on the Application of Cool Paintings for the Passive Cooling of Existing Buildings in Mediterranean Climates

On Innovative Cool-Colored Materials for Building Envelopes: Balancing the Architectural Appearance and the Thermal-Energy Performance in Historical Districts

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