Effects of soiling and weathering on the albedo of building envelope materials: Lessons learned from natural exposure in two European cities and tuning of a laboratory simulation practice

Paolini, Riccardo; Terraneo, Giancarlo; Ferrari, Chiara; Sleiman, Mohamad; Muscio, Alberto; Metrangolo, Pierangelo; Poli, Tiziana; Destaillats, Hugo; Zinzi, Michele; Levinson, Ronnen

doi:10.1016/j.solmat.2019.110264

Cited by 34 publications

(16 citation statements)

References 40 publications

(94 reference statements)

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“…As such, [71] found that increasing the albedo of all roofs in Sydney can reduce the UHI by 0.6 • C, while [80] reported that an increase in the albedo of 60% of Melbourne's rooftops can lead to a cooling potential of 0.5 • C. Furthermore, the thermal performance of a cool roof depends on many factors, such as local climatic conditions (solar radiation intensity, humidity, wind speed, and cloud cover), the solar reflectance and thermal emittance of roof materials, heat capacity, and U-value of the roof [65]. Moreover, ageing can remarkably reduce the solar reflectance-and thus the cool roof direct and indirect benefits-even by more than 20% during the first years for cool roofing materials with initial albedo equal to 80%, as documented with natural exposure programs conducted in the US, Europe, Brazil, and Japan [112].…”

Section: Cool Roofs and Façadesmentioning

confidence: 80%

Urban Overheating and Cooling Potential in Australia: An Evidence-Based Review

Yenneti

Ding

Prasad

et al. 2020

Climate

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Cities in Australia are experiencing unprecedented levels of urban overheating, which has caused a significant impact on the country’s socioeconomic environment. This article provides a comprehensive review on urban overheating, its impact on health, energy, economy, and the heat mitigation potential of a series of strategies in Australia. Existing studies show that the average urban heat island (UHI) intensity ranges from 1.0 °C to 13.0 °C. The magnitude of urban overheating phenomenon in Australia is determined by a combination of UHI effects and dualistic atmospheric circulation systems (cool sea breeze and hot desert winds). The strong relation between multiple characteristics contribute to dramatic fluctuations and high spatiotemporal variabilities in urban overheating. In addition, urban overheating contributes to serious impacts on human health, energy costs, thermal comfort, labour productivity, and social behaviour. Evidence suggest that cool materials, green roofs, vertical gardens, urban greenery, and water-based technologies can significantly alleviate the UHI effect, cool the ambient air, and create thermally balanced cities. Urban greenery, especially trees, has a high potential for mitigation. Trees and hedges can reduce the average maximum UHI by 1.0 °C. The average maximum mitigation performance values of green roofs and green walls are 0.2 °C and 0.1 °C, respectively. Reflective roofs and pavements can reduce the average maximum UHI by 0.3 °C. In dry areas, water has a high cooling potential. The average maximum cooling potential using only one technology is 0.4 °C. When two or more technologies are used at the same time, the average maximum UHI drop is 1.5 °C. The mitigation strategies identified in this article can help the governments and other stakeholders manage urban heating in the natural and built environment, and save health, energy, and economic costs.

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Section: Cool Roofs and Façadesmentioning

confidence: 80%

Urban Overheating and Cooling Potential in Australia: An Evidence-Based Review

Yenneti

Ding

Prasad

et al. 2020

Climate

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“…A roof with high thermal mass but a dark surface may behave similar to a roof with a relatively low mass and thermal inertia but with a highly reflective surface. A highly reflective surface would almost nullify the effects of the solar cycle; nevertheless, it would be difficult to preserve due to soiling or biofouling, hence the lower solar reflectance of the aged surface must be considered [31,32]. Moreover, highly reflective surfaces are white, but different, less reflective colors may be compulsory for historical or traditional buildings or even entire urban areas.…”

Section: The Solar Transmittance Factor (Stf) and The Solar Transmittance Index (Sti)mentioning

confidence: 99%

Analysis of a New Index for the Thermal Performance of Horizontal Opaque Building Components in Summer

et al. 2021

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The summer behavior of an opaque building component subjected to the solar cycle depends on the combination of its thermal insulation, inertia, and solar reflectance. To rate the component dynamic behavior while an air conditioning system ensures a steady indoor temperature, a ‘solar transmittance index’ (STI) has been proposed. This is a component-based index calculated from a ‘solar transmittance factor’ (STF). STI takes into account the radiative properties at the outer surface and the thermophysical properties and layer structure of the materials beneath. It correlates the peak heat flux and temperature at the inner surface, relevant to cooling energy and thermal comfort, to the peak solar irradiance. Similar to the well-known ‘solar reflectance index’, STI is determined comparing the STF with two reference values, corresponding to a performance relatively low and very high, respectively. Thanks to its simplicity, the approach may allow defining easy to apply requirements to prevent building overheating, improve indoor comfort, reduce cooling energy demand, and mitigate some fallouts of the urban heat island effect. In this work, focused on roofs above occupied attics, peak heat flux and ceiling temperature are calculated by numerical simulation and compared with STF values for a wide range of roof types.

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“…La existencia de una amplia gama de productos y tecnologías de estabilización química de suelos, hace necesario que se realice una selección adecuada mediante la evaluación de su durabilidad, propiedad que está relacionada con la resistencia al intemperismo, a la erosión o a la abrasión del tránsito de aquellos suelos cercanos presentes en la superficie de rodadura (Camacho Tauta et al, 2008). Los suelos, y en general todos los materiales expuestos a la intemperie, pueden sufrir deterioros por condiciones ambientales como la lluvia, la radiación UV, el rocío, la humedad; de allí la importancia de poder conocer la incidencia de estos factores, individuales y combinados, sobre sus propiedades (Paolini et al, 2020). Es así como resulta de gran interés el uso de Studies in Engineering and Exact Sciences, Curitiba, v.3, n.1, p.2-15, jan./mar.…”

Section: Introductionunclassified

Efecto del intemperismo sobre las propiedades fisicoquímicas, el desempeño y la durabilidad de suelos viales aditivados con estabilizantes químicos

Llano¹,

Restrepo²

2022

SEES

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El deterioro y agotamiento progresivo de las fuentes de suministro de materiales adecuados para la construcción de infraestructura vial ha llevado al desarrollo de técnicas alternativas de mejoramiento de suelos, dentro de éstas la estabilización química de suelos se presenta como una alternativa técnica, económica y ambientalmente sostenible enfocada al mejoramiento de caminos sin pavimentar de bajo volumen de tránsito. Esta técnica de mejoramiento de suelos consiste en el empleo de productos químicos para mejorar las propiedades ingenieriles de los suelos, reduciendo su plasticidad y haciéndolos más resistentes, ante la acción del tráfico y condiciones ambientales a las que están expuestos. Los estabilizantes químicos que han sido empleados para el mejoramiento de suelos pueden clasificarse, según su naturaleza química, en: polímeros, aceites sulfonados, organosilanos, puzolanas y enzimas. Estas alternativas de mejoramiento de suelos han sido usualmente orientadas a caminos sin pavimentar de mediano y bajo volumen de tránsito, donde el desgaste y la durabilidad de los materiales es debido principalmente a factores climáticos y de intemperismo natural. El intemperismo deteriora los materiales expuestos al exterior produciendo cambios de color, superficies más rugosas, fisuramiento, agrietamiento, pérdida de cohesión y fragmentación, lo que finalmente se traduce en una pérdida de resistencia y efectividad de estos. El intemperismo acelerado es una alternativa que permite evaluar en periodos cortos de tiempo la evolución de las propiedades fisicoquímicas de los materiales y predecir su comportamiento a largo plazo, para ello se cuenta con cámaras de envejecimiento acelerado donde se exponen los materiales a ciclos alternados de luz ultravioleta (UV) y humedad, todo ello a temperaturas elevadas y controladas. The progressive deterioration and depletion of the sources of materials supply suitable for the construction of road infrastructure, the wide variety of soil types and low sustainability and durability of constructive solutions has stimulated the emergence and alternative construction systems evaluation for road sections stabilization, treatment or rehabilitation. Among them, chemical soil stabilization is presented as a technically, economically and environmentally sustainable alternative focused on improving medium and low-volume unpaved roads. This technique involves the use of chemicals to improve the soils engineering properties in order to reduce its plasticity and increase their strength to the action of traffic and environmental conditions to which they are exposed. Chemical stabilizers that have been used for soil improvement can be classified according to their chemical nature, in: polymers, sulfonated oils, silanes, pozzolans and enzymes. These alternatives for soil improvement have been usually aimed over medium and low-volume unpaved roads, where materials wear and durability is mainly due to climatic and natural weathering factors. Natural weathering deteriorates the exposed external materials and it produces color changes, rougher surfaces, fissuring, cracking, fragmentation and loss of cohesion which results in a strength loss, effectiveness and functionality of these materials. The accelerated weathering is a methodology to evaluate the material physicochemical properties evolution in short periods of time and predict long-term behavior by combining the most unfavorable environmental conditions to which the material would be exposed during a relatively long period. For this purpose, tests are performed using a QUV accelerated weathering tester, in which the materials are exposed to alternating cycles ultraviolet light (UV) and moisture. All at high and controlled temperatures. In this research work it intends to evaluate accelerated weathering's effect on the performance and durability of a soil additive with chemical stabilizers of different nature, using a QUV accelerated weathering tester to recreate real environmental conditions, simulating and controlling parameters such as: temperature, humidity (condensation and water spray) and ultraviolet light exposure. This makes it possible to know the behavior and performance of this type of materials over time under weather conditions.

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Effects of soiling and weathering on the albedo of building envelope materials: Lessons learned from natural exposure in two European cities and tuning of a laboratory simulation practice

Cited by 34 publications

References 40 publications

Urban Overheating and Cooling Potential in Australia: An Evidence-Based Review

Urban Overheating and Cooling Potential in Australia: An Evidence-Based Review

Analysis of a New Index for the Thermal Performance of Horizontal Opaque Building Components in Summer

Efecto del intemperismo sobre las propiedades fisicoquímicas, el desempeño y la durabilidad de suelos viales aditivados con estabilizantes químicos

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