2,104 research outputs found

    The effect of incorporating high reflectance pigments in thermal enhanced exterior finishing systems

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    In the recent years, the concerns on building thermal performance tend to follow the challenges imposed by more demanding building design. The increase of new building materials and technologies with improved thermal characteristics, such as ETICS, thermal mortars and high reflectance coatings, contribute to meet the thermal requirements, by lowering the façade U-value and/or the surface temperature variation. This paper has the objective of evaluating the effect of incorporating high reflectance pigments in organic coatings applied in thermal systems, such as ETICS and thermal rendering. The effect on the thermal behaviour is also discussed by comparing them with a non-insulated system. The solar absorptance and the surface temperature of different façade systems with distinct coatings were measured "in situ". The solar absorptance was measured with a pyranometer with an adapted methodology based on the ASTM E1918 standard. The surface temperature of the specimens was continuously monitored for an extended period enabling a comparison under different climatic conditions. The results showed that the incorporation of high reflectance pigments allowed a significant decrease of the solar absorptance even in darker colours and that the absence of thermal insulation proved to have a significant effect on the surface temperature

    NIR reflective finishing coatings with nanoparticle inclusion

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    About 40% of the energy consumption of European countries are attributed to buildings. For the construction sector development, it is necessary to ensure the enhancement of sustainability in buildings, eventually by designing new energy- efficient buildings. To accomplish such goal it is crucial to reduce the amount of solar radiation absorbed by buildings. Several solutions have already been reports in the literature, being the development of coatings with high reflectance of the solar energy for envelope system one of the promising methods to be effective in reducing the thermal gains in buildings. Coatings that contain near-infrared reflective nanomaterials can be applied onto a surface (such as roofs, pavements or, façades) exposed to solar radiation to reducing its radiation absorption. Our study aimed the development of innovative finishing coatings for envelope systems by increasing their solar reflectance through new material formulations with the inclusion of nanoparticles. We studied the reflectance and colour properties by doping a standard black colorant with different types and sizes of nanoparticles (TiO2 in rutile and anatase phase, Al2O3 and CuO), in an acrylic substrate. In particular, such nanoparticles were used with the concentration in the coating being varied (1% to 20%). The results obtained can help formulate new finishing coatings with increased near-infrared reflectance of buildings façades, using, for instance, more than one type of nanoparticles or core-shell structures

    Durability of etics incorporating high reflectance pigments in finishing coatings

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    The increase of the durability of building materials and components presents great importance since it contributes to a more sustainable environment by increasing its service life. The development of new building materials and technologies with improved thermal characteristics, such as ETICS with high reflectance coatings, contributes to meet the thermal requirements defined by the European regulation. However, the importance of the durability assessment of new solutions cannot be understated as it plays a key role in the prevention of future early degradation. This paper has the objective of assessing the durability of ETICS incorporating high reflectance pigments in organic coatings. The solar reflectance can be increased through optimized material formulations with the inclusion of nanoparticles in coatings. If the near-infrared (NIR) solar absorption is reduced, the referred benefits can be achieved even in darker colours. One of the main concerns is the durability of the entire system, but the stability of the darker colours must also be taken into account. As such, relevant parameters solar absorptance, surface temperature and colour were measured in a long-term in-situ experimental campaign, in ETICS specimens with distinct coatings. The effect of the thermal insulation layer, in the referred parameters, was also evaluated, by measuring the effect of the same coatings in samples with traditional substrates. The solar absorptance was measured with a pyranometer with an adapted methodology based on the ASTM E1918 standard. The surface temperature of the samples was continuously monitored for an extended period enabling a comparison of the benefits under different climatic conditions. The colour was determined by the CIELAB colour space, by measuring the L*A*B parameters. The results showed that the incorporation of high reflectance pigments leads to a decrease in the solar absorptance and surface temperature even in darker colours. The pigments also influenced the lightness of the coating, by increasing the L parameter. The potential benefits of these thermal enhanced systems combine an enhanced thermal performance, durability and a higher diversity of aesthetic features

    Colour degradation of facade coatings - the effect of nanopigments incorporation

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    The increasing interest in the use of a wide range of colours in buildings, especially dark colours, may lead to the early degradation of the facades, compromising their aesthetic and thermal performance. On the other hand, the incorporation of nanopigments with high reflectance properties can contribute to reducing the absorption of solar radiation. The nanoparticles contribute to increasing the solar reflectance of coatings, decreasing the surface temperature and improving the coating performance. This work evaluates the natural degradation of the colour of finishing coat with nanopigments in ETICS. The colour parameters were evaluated in different ETICS specimens, considering the colour black and red with and without incorporated nanopigments, under natural ageing. The colour measurement was performed according to ISO 1164-4, using a portable spectrophotometer. The results confirmed that the use of nanopigments improved the colour durability, promoting the maintenance of the colours parameters. The total colour difference was lower than the perceptible by the human eyes, even as the lower variation on chroma and hue parameters of the colours with nanopigments. In summary, the incorporation of nanoparticles in finishing coat of ETICS can contribute to increasing their durability and improve their thermal performance without compromising the aesthetic characteristics

    Solar reflectance of ETICS finishing coatings - a comparison of experimental techniques

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    The solar reflectance has a significant role in the thermal behaviour and surface temperature of ETICS finishing coats. Incomplete information of solar reflectance of ETICS with nanopigments can sometimes difficult their adequate selection. In this work, the solar reflectance of different ETICS finishing coats was measured using two distinct methodologies, and the importance of the adopted procedure was discussed. The experimental methodologies used were: i) the adapted conventional pyranometer technique (non-ASTM E 1918A), which measures the global solar reflectance; and ii) the use of the spectrophotometry, to measure the spectral reflectance. It was verified that the El 918A methodology is more sensitive to environmental conditions than the spectrophotometry procedure. Also, the calculation of solar reflectance with spectrophotometer can be carried out by the 50 or 100 ordinates. However, the surface characteristics, as the concentration of pigments and roughness, affect more the solar reflectance measured with the spectrophotometer than with the pyranometer. It was verified that the nanopigments could improve solar reflectance and change the spectral reflectance. The results showed that, if the procedure is well applied, both methodologies could be used to evaluate the advantages of incorporating nanopigments in facade finishing coatings and also to assess the durability of these materials

    Landscape Ecology dialogue: facing societal and environmental challenges in Southern Europe

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    A Universidade de √Čvora aprovou, em 2013, o Mestrado em Ecologia da Paisagem, o 1¬ļ em Portugal, cuja 1¬™ edi√ß√£o vai ter lugar no pr√≥ximo ao letivo. A presente confer√™ncia tem como objetivo dar a conhecer e divulgar o referido mestrado aos potenciais interessados, trazendo para o di√°logo os desafios que atualmente se colocam em Ecologia da Paisagem, nomeadamente os sociais e ambientais, num contexto transdisciplinar que lhe √© inerente. Ser√£o abordados temas dentro de um vasto leque de realidades, quest√Ķes e escalas de an√°lise, desde o ensino √† investiga√ß√£o e √† sua aplica√ß√£o pr√°tica, para o que se convidaram especialistas e investigadores de diferentes pa√≠ses, com diferentes compet√™ncias e forma√ß√Ķes. Pretende-se identificar as quest√Ķes mais atuais e os desafios a considerar no futuro, articulando ensino e investiga√ß√£o e equacionado de que forma a Ecologia da Paisagem contribui para dar resposta √†s r√°pidas transforma√ß√Ķes e din√Ęmicas territoriais e ambientais. As apresenta√ß√Ķes da confer√™ncia podem ser solicitadas √† organiza√ß√£o por correio electr√≥nico

    Durability of a New Thermal Aerogel-Based Rendering System under Distinct Accelerated Aging Conditions

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    The widespread application of innovative thermal enhanced facade solutions requires an adequate durability evaluation. The present work intends to assess the durability of a new aerogel cement-based rendering system through the adaptation of different accelerated aging cycles, such as heating-freezing, freeze-thawing, and heat-cold. Several mechanical properties and also capillary and liquid water absorptions were tested for uncoated and coated specimens. A decrease in the mechanical strength, especially after freeze-thaw cycles, was observed. However, the water action promoted the late hydration of the cement paste contributing to the densification of the matrix and, consequently, the increase of the adhesive strength. Additionally, a decrease in the dynamic modulus of elasticity and an increase in the Poisson's ratio were observed after aging, which indicates a higher capacity of the render to adapt to substrate movements, contributing to a reduction of cracking

    Impact of air barriers application in LCA and LCC of naturally ventilated dwellings in mild climate regions

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    "Available online 17 November 2022"Assessing singular elements that constitute the air barrier of a building envelope is quite unfeasible in Life Cycle Assessment (LCA). The study of these solutions through this particular scope is often overlooked. Two major aspects contribute to it: the complexity of the relationships between elements and the reduced embodied impact of these materials in the overall construction or retrofitting works. This work uses LCA and Life Cycle Costing (LCC) to study the viability of applying two envelope air barrier solutions in dwellings with excessive air change rates and equipped with different heating systems. The application of air barrier solutions resulted in average energy consumption savings in urban terrain, almost half of those in rural terrain during the heating season. Environmental performance and life cycle costs revealed mechanically (MECH) fastened air barriers to outperform fluid (FLUID) applied ones. The median annualized cost of adopting a FLUID solution was almost four times that of a MECH solution. Dwellings equipped with electric radiators ranked first in the shortest average Energy Payback Period (EPP) and the highest average Reference Service Life (RSL) savings. With the current analysis, the adoption of MECH solutions is recommended, independently of the heating system the dwelling is equipped with.This work was financially supported by: Base Funding - UIDB/04708/2020 and Programmatic Funding - UIDP/04708/2020 of the CONSTRUCT - Instituto de I&D em Estruturas e Constru√ß√Ķes - funded by national funds through the FCT/MCTES (PIDDAC). The author would like to acknowledge the support of FCT - Funda√ß√£o para a Ci√™ncia e a Tecnologia, the funding of the Doctoral Grant PD/BD/135162/2017, through the Doctoral Programme EcoCoRe. This work is supported by the European Social Fund (ESF), through the North Portugal Regional Operational Programme (Norte 2020) [Funding Reference: NORTE-06-3559-FSE-000176]
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