Estudo de materiais naturais para aplicação em isolamento térmico de edificações

Abstract

As crises energéticas e os impactos climáticos revelaram a necessidade de se repensar a forma de projetar as edificações, que se apresentam como grandes geradores de gases causadores do efeito estufa e consumo de 40% da energia elétrica mundial. A ONU e diversos países vem redigindo recomendações e legislações sobre o tema, orientando a utilização de materiais adequados, visando a eficiência energética em edificações. Este estudo se desenvolveu a partir de uma metodologia de pesquisa bibliométrica, buscando por materiais de isolamento térmico para utilização em edificações, que possam substituir materiais convencionais que utilizam recursos não renováveis e poluentes no seu sistema de fabricação. Grande parte dos materiais naturais pesquisados, surgem oriundos de resíduos agrícolas, que podem ser tratados, e utilizados como material construtivo. Os estudos pesquisados apontam desempenho de condutividade térmica (λ) abaixo do recomendado para materiais isolantes (λ < 0,07 W/m.K). Assim, materiais que poderiam ser considerados resíduos, surgem como nova alternativa construtiva. Os estudos desenvolvidos a partir da casca de arroz (λ = 0,0464 W/m.K), folha de abacaxi (λ = 0,0380 W/m.K), bagaço de cana (λ = 0,0460 W/m.K) e sabugo de milho (λ = 0,0580 W/m.K) apresentam resultados importantes, além de serem alternativas viáveis para serem utilizadas no Brasil, por haver grandes áreas de plantio para estas culturas. Salienta-se a importância de se desenvolver pesquisas práticas da aplicabilidade destes materiais, bem como testes de resistência ao fogo e Avaliação do Ciclo de Vida (ACV).

Development of Methodology for Determining the Physical Properties of Natural and Innovative Materials

“…3). Compared to the data presented in Graph 1, the conductivity of soybean straw resembles the conductivity of other materials of plant origin such as reeds, whose thermal conductivity comprises from 0.045 to 0.056 W / mk and the straw whose thermal conductivity varies between 0.045 to 0.07 W / mk, this being not of soybean, but of low grass [22]. The density test of the Soybean Straw plate, the apparent density measured in a 25 ml beaker, was 162 kg / m³, and in the test to determine the actual density, the value of 238 kg / m³, similar to the given by Marcos [11], where the density of the grass straw was 260 kg / m³.…”

“…The results obtained in the determination of the thermal conductivity were 0.061 W / mk and, compared with Graph 1, the conductivity value for the pine bark was approximately 0.07 W / mk (Spinelli et al, 2018b ; We highlight here the similarity of the studied plant species, and the proximity of the result found, being applied different tests, as presented by Marcos [11]. The results for the apparent density and actual density tests were, respectively, 232 kg / m³ and 331 kg / m³.…”

“…Further research indicates unconventional materials, such as natural or innovative materials, to be applied in civil construction as thermal insulation, with the main advantage being that they are renewable and have a low impact on the generation of pollution at the moment of production, as can be shown in the Graphic 1 [2,22].…”

“…The mortar board with acrylic box and vacuum interior was collected from the study developed by Spinelli et al [23]. As shown in Figure 6, the plates are composed of: a) Acrylic plate with laser cutting technology; b) Compressor and manometer for withdrawal of air -vacuum; c) First layer of mortar; d) Insertion of the acrylic box with vacuum layer wrapped with glass fiber cloth; e) Second layer of mortar; f) Proposed element finalized.…”

“…As shown in Figure 6, the plates are composed of: a) Acrylic plate with laser cutting technology; b) Compressor and manometer for withdrawal of air -vacuum; c) First layer of mortar; d) Insertion of the acrylic box with vacuum layer wrapped with glass fiber cloth; e) Second layer of mortar; f) Proposed element finalized. The total thickness of the plate was 4 cm, were taken from a prototype used for thermal comfort test, in which the study's sequence is important to determine the thermal conductivity of the material, and thus to analyze its efficiency in more depth [23]. The material analyzed for slimstone, is produced by the company SlimStone, located in the municipality of Garibaldi / RS.…”