Aproveitamento da água da chuva para fins de irrigação em condomíno fechado: proposta para obtenção do selo LEED

Abstract

Sustainability in Civil Construction has become a routine topic in several discussions at world events since the Great Oil Crisis, in 1970, aiming at awareness and prevention of natural resources. One of the main points discussed is the preservation of water resources, which for many years was thought of as an infinite resource, causing a lot of waste and, nowadays, many water rationing measures, in order to curb the depletion of these means. As a result of the years, from the mid1980s onwards, an incentive for the preservation of natural resources emerged in developed countries: the LEED seal, with a kind of prize for those who fulfilled its requirements, a form of incentive for sustainable construction. In Brazil, it entered the market with greater intensity from the 2000s onwards, having among its requirements the Water Management. This work presents a study on the technical and economic feasibility of implementing a rainwater harvesting system to supply an electronic irrigation system (with an area of 3,000m²) in a closed condominium in Alegrete-RS. The idea arises from the quarterly cost verification, which shows a high expenditure on water from the concessionaire, used for the irrigation of a green area in one of the enterprise's squares. In the draft it is defined that it will not be possible to change the already built architecture of this square, without apparent works of art/structures, so a storage system with buried tanks with predefined sizes due to the scarcity of space is chosen. First, a hydrological characterization of the city was carried out, with analysis of a 10-year historical series, in order to characterize the amount and distribution of rainfall over the days/months/years. After defining the average annual and monthly rainfall, it was decided to design the reservoirs, using methods defined by NBR 15527 (ABNT, 2007), for the economic and social evaluation of the project. Implementation costs proved to be low, economically viable, with a turnaround time of 20 months. However, as shown in the project, it does not have total solidity due to poor rainfall distribution and low storage capacity, due to the lack of space for a structure with greater capacity. Keywords: LEED seal, rainwater harvesting, economic viability.