Avaliação do desempenho térmico e acústico em paredes do sistema light steel framing compostas por manta de lã de PET e placa de vermiculita

Abstract

Encouraging the use of environmentally friendly construction systems is one of the key elements in the face of the current demand for more sustainable buildings. In this context, the main objective of this research is to evaluate the acoustic and thermal performance of walls in the Light Steel Framing (LSF) construction system, using recycled-PET fiber and vermiculite board as sound absorption and thermal insulation materials, based on ABNT NBR 15575-4:2021 - Residential Buildings - Performance. Thermal performance analysis involved experimental tests for thermal transmission in LSF panels and simplified calculations according to ABNT NBR 15220:2022 - Thermal Performance of Buildings. The acoustic performance analysis was conducted through experimental tests to determine: the sound absorption coefficient and acoustic impedance of recycled-PET fiber and vermiculite board; sound transmission loss (STL) tests at ambient temperature and under wall heating conditions in LSF walls; and theoretical estimation of STL. The LSF wall tests were conducted with fiber cement board on the external side and OSB board and gypsum board on the internal side, with four different configurations in the internal cavity: one model without any material inside the wall; the second with only recycled-PET fiber; the third with only vermiculite board; and the last model with recycled-PET fiber and vermiculite board. In terms of thermal performance, the panel with both materials achieved the lowest maximum temperature and exhibited slower heating and cooling compared to the other three panel configurations, whereas the panel without any absorptive material inside experienced rapid heating and cooling. The acoustic performance analysis revealed that the combination of recycled-PET fiber and vermiculite board in LSF walls exhibited higher STL in frequencies between 1250 Hz and 4000 Hz, while the wall with only vermiculite board showed higher STL in frequencies between 100 Hz and 1000 Hz. The test with only recycled-PET fiber presented the lowest STL across most of the evaluated frequencies. Thus, the proposed assembly in this study met the minimum requirements established by ABNT NBR 15575-4:2021. As for thermal performance, specific evaluations for each climate region of the country are necessary, but the assembly complied with the performance standard in terms of thermal transmittance (U) for the eight Bioclimatic Zones, defined by ABNT NBR 15220:2005. Regarding the acoustic performance, the proposed assembly with the two investigated materials can be used in external facades of rooms and bedrooms in buildings, according to the Rw value. Every architectural project must take into account the climate of the region and the noise class in which the building is located, in order to achieve acoustic and thermal performance, providing well-being to the user. Finally, this research stimulates the discussion on more sustainable buildings, which contribute to reducing energy and economic demands, disseminate knowledge about rationalized construction, and promote the use of vermiculite board, a material not widely explored in the LSF construction system.