RESUMO
Rainwater Harvesting Systems (RWHS) are an alternative solution with the potential to increase water supply security and reduce the pressure on water resources and urban stormwater drainage systems. Likewise, Green Roofs are a nature-based solution with several ecosystem services able to improve well-being in densely urbanized areas. Despite these benefits, the combination of both solutions is still a knowledge gap to be explored. To address this issue, the paper explores the potential of integrating traditional rainwater harvesting systems (RWHS) with extensive green roofs (EGR), while simultaneously evaluating the performance of traditional RWHS in buildings with high and variable water consumption patterns across different climatic conditions. The analyses were carried out assuming two university buildings hypothetically located in three distinct climates (Aw - Tropical Savanna, Cfa - Humid Subtropical, and Csa - Hot-summer Mediterranean). The results show that the relationship between available water and demand is the key factor that defines if the system is most suitable for saving water, reducing stormwater runoff rates, or dual-purpose (when there is a balance between non-potable water supply and capture of stormwater). Combined systems were most effective when there is a balanced rainfall distribution over the year, as in humid subtropical regions. Under these conditions, a combined system designed for dual purposes could potentially have a green roof coverage of up to 70% of the total catchment area. Conversely, climates that have well-defined rainy and dry seasons such as Aw and Csa, may limit the effectiveness of a combined system (RWHS+EGR), being not able to supply water demands during certain periods of the year. However, if the primary objective is effective stormwater management, a combined system should be strongly considered. Because green roofs provide other ecosystem benefits that can contribute to enhancing urban resilience in the face of climate change.
RESUMO
Knowing water and energy consumption patterns sets the baseline for understanding their drivers and assessing the performance of potential measures to increase efficiency and/or reliability. These patterns can vary substantially depending on the building characteristics, on the building users and use, on the cultural, social, economic, environmental context in which the building is located, among many other factors. This article presents a general methodological framework for characterizing water and energy consumption patterns in buildings based on the evaluation of the characteristics of the equipments and appliances, as well as the type of users and the activities developed in each type of room. This allows estimating water and energy use, by end use per square meter and by roomtype. The methodological framework proposed was applied to the buildings of the Paricarana Campus of Federal University of Roraima (UFRR), Brazil, providing one of the few examples in the literature reporting water and energy consumption in university buildings in tropical climates. Universities, in most cases, represent large water and energy consumers with distinctive consumption drivers and patterns which have received limited attention when compared to other types of buildings (e.g., residential). The findings have shown that teaching rooms and administration rooms are the main consumers, representing 48% and 49% of the institution's energy and water consumption, respectively. Air conditioning is the biggest energy consumption (63%), while personal use represents 72% of the total water consumption in a building. The toilets represent a large water consumption in a university building (46.40%). Comparing different building uses, the central library is the highest consumer, due to the longest operating time and the highest occupational density. The methodological proposal intends to be a useful tool to support managers and decision-makers to understand the dynamics of consumption and then propose effective practices to reduce water and energy uses, as well as providing reference data for comparison with other educational institutions.
