Comparativo do desempenho térmico, interceptação de chuvas e econômico entre telhados de fibrocimento e verde produtivo

Abstract

This study aimed to evaluate the thermal, rain interception and economic performance of two roof systems, fiber cement roof and productive green roof, based on their adoption in buildings of popular housing interest. For the development of the study, an experimental bench was used that simulates a conventional roof covered with fiber cement tiles and a green roof with vegetables on fiber cement tiles. The experimental design used was completely randomized (DIC), the structure of the bench is divided into eight modules with 04 repetitions of each treatment (fiber cement roof and productive green roof), with dimensions of 2.21 x 4.15 m, with each module measuring 0.85 x 1.0 m, with an area of 0.85 m². In the productive green roof treatment, the vegetable species lettuce (Lactuca sativa), chives (Allium fistulosum), parsley (Petroselinum crispum) and beet (Beta vulgaris L.) were used. The thermal variables analyzed were: surface temperature (measured with an Icel infrared thermometer - TD-955), internal air temperature (measured with digital thermometers in the modules) and external temperature (data from the automatic station INMET/UTFPR-DV). Collections took place fortnightly from December 2021 to December 2022, at 9 am, 12 pm, 3 pm and 6 pm. Surface runoff was measured after rain events using 20,000 ml containers and a 1000 ml graduated cylinder, allowing the calculation of the interception percentage of each type of coverage. Precipitation was recorded by the automatic station. Data processing was performed using a Microsoft Excel® spreadsheet and statistical analyses of thermal, interception and runoff behavior were performed after a mean comparison test using the Tukey test at 5.0%, in the SASMAgri® Software. An analysis of the productive viability of the species implemented and the economic viability of the types of coverage were also carried out, based on the costs of implementation, maintenance and financial return. An estimate of the economic viability was then made for a tenyear projection horizon, a projection applied to social housing of 36 m². The green roof demonstrated better thermal and hygrometric performance compared to the fiber cement roof, promoting greater stability of the internal microclimate and environmental comfort. It showed efficiency in moisture retention, with less seasonal variation, and average interception of 70.1% of rainwater, contributing to the control of urban flooding. The estimated horticultural production was 952.4 kg/year on 36 m² roofs. The economic analysis indicated viability, with return on investment in the 4th year and accumulated net income of R$ 118,805.97 in ten years. Despite the high initial cost, the green roof proved to be more profitable. The need for prior structural evaluation and continuous maintenance is emphasized to ensure its effectiveness and safety.