Frontiers in Civil Engineering

Water savings in buildings has become a matter of concern due to water demand increase in cities and to problems with water quality and availability. This chapter presents the state of the art on water savings in buildings in Brazil. Journal and conference papers, reports and theses published from 2003 to 2016 were reviewed. First, in order to show the main shortage problems faced by Brazilian people, the national panorama of water resources is shown. Then, papers about the use of rainwater, water quality, potential for potable water savings, investment feasibility analysis, greywater reuse and water-efficient appliances are also addressed. Water enduses in buildings, environmental education, and national water savings support programmes are also presented. It was observed that there is a high potential for potable water savings in buildings by using rainwater for non-potable purposes in Brazil.

Water supply is an essential service to buildings along with other services such as electricity supply and telephone. Many of the new cities in developing countries do not have 24-hour safe drinking water in their buildings, and water supply is often intermittent and is of poor quality. In contrast, developed countries use a much higher volume of potable water in their buildings, which can be reduced significantly. In urban areas, sustainability and water efficiency of buildings are of great significance as many water authorities have been struggling to meet the increasing water demand due to higher populations. The climate change is bringing more extremity in the climate systems such as long and frequent droughts and higher temperature episodes, which increase water demand significantly when water availability is the lowest. This chapter presents water recycling and reuse in buildings with a special focus on rainwater harvesting systems in Australia to reduce potable water demand within buildings. It has been found that rainwater harvesting is one of the most popular means of alternative water supplies in buildings; however, there are further scopes of development in the rainwater harvesting systems by bringing innovations into these systems to make future buildings more water-efficient.

Rainwater Harvesting (RWH) systems are recognized as a widely accepted solution to save potable water in buildings. In addition, RWH systems may play an important role in mitigating the impact of increasing imperviousness in urban areas by contributing to increase both at-source retention and detention of storm water runoff. The chapter provides an overview of methodologies for designing RWH systems, with specific focus on numerical models based on the long-term water balance simulation of the tank. An overview of metrics to evaluate RWH system performance is presented, with regard to the estimation of both water saving potential and storm water control benefits. The accuracy of the modelling results with reference to the length of the available rainfall series and to the selected resolution time step of the used model is discussed. Results of an application to six cities in southern Europe are also discussed in order to highlight the impact of different precipitation regimes as well as the influence of rainwater demands on the system design and performance. Finally, the German, British and Italian standards on RWH are analysed and compared to identify differences and common design approaches.

This chapter presents an approach for using multi-criteria decision analysis (MCDA) to study the tradeoffs of rainwater harvesting (RWH) system designs. Three scenarios have been designed and evaluated. Each one captures rainwater from the rooftops of the connected Civil and Materials Engineering (CME) and Hedco buildings on the University of Utah campus. Scenario 1 utilizes two separate storage cisterns; one large underground, and one smaller placed on the top of the CME building. Scenario 2 utilizes only one large underground cistern. It uses a pressure-regulated pump to supply a constant flow of water to each toilet in the building. Scenario 3 utilizes only one large cistern placed on top of the CME building. The design includes a pump to convey collected runoff from the Hedco building to the rooftop cistern. From there, toilets are flushed from the gravity-fed water. MCDA was used to integrate environmental impacts, cost, water use and social impacts of the proposed scenarios. GaBi software was used for environmental impact analysis; TRACI and ReCiPe were used as assessment tools. After assessment of the designs, it is suggested that Scenario 3 represents the most favorable option for any change to the toilet-flushing system in the CME.

Technology upgrades or investment in changing user behaviour? This is a common dilemma when it comes to improving water savings in administrative buildings. The answer is obvious: both, but only after a management scheme is in place. Several real scale experiments have been carried out at the Federal University of Bahia, Brazil, and in the administrative buildings of the government of the State of Bahia over the last 17 years with significant results however, less than expected. This paper discusses the role played by so-called water saving devices and that played by maintenance activities and continuous calibration. A conceptual scheme to guide water savings in buildings as well as actions that must be considered in water saving programmes are presented. The conceptual guide considers the role of following-up water consumption on a daily basis by administrators but with data open to the public. It further presents an approach to understanding the reasons for water losses and water waste and the means to reduce them in institutions with clear technical and economic limitations. Consumption monitoring and control is the most important action to be taken and this has to precede further efforts or investments such as the acquisition of water saving devices or greywater use and rainwater catchment.

Nowadays, water management is necessary to optimize the use of this key resource. As such, increasing water efficiency through the reduction of consumption and/or resorting to alternative water sources is a challenge of the near future. Rainwater harvesting is an accessible alternative source of water for non-potable and potable uses in many parts of the globe. Rainwater can be collected easily and, in many cases, its use may not require significant treatment, even for potable purposes. Yet, rainwater harvesting (RWH) systems are still not common in most of the water supply projects, namely in Mediterranean countries such as Portugal. The promotion of RWH systems involves viability analyses estimating the expected water savings for different climate and water consumption patterns. This chapter evaluates the performance of rainwater harvesting systems of several case studies in Portugal, covering different water use patterns and geographical locations. The water consumption pattern, both in time and end-use, influences the potential for rainwater use. Water consumption was monitored in residential buildings (a single family house and a building), a shopping centre and a university building. Simulations are presented for different locations in Portugal, in order to assess the influence of weather in the efficiency of RWH systems. In addition to the rainfall amount, its distribution in time and space also contributes for the rainwater availability. The operational data from an existing rainwater harvesting system is used to calibrate the model and evaluate its sensitivity to the main parameters. Tank optimization for each case study is discussed. The Mediterranean climate, characterized by distinct wet and dry seasons and significant variability of the rainfall events intensity and duration, shows substantial variation of the inter-annual water savings from a rainwater harvesting systems. The results show that rainwater harvesting systems in Portugal are a relevant alternative water source in different types of building.

This chapter focuses on the health issues related to the application of Water Saving Systems (WSS) in buildings. It stars by showing the environmental and economic advantages of these systems and then presents the main obstacles to their large-scale implementation: concerns about water quality, the security of the users and the implications on the public infrastructures. For these reasons, it is important to carefully study this question, list all health issues related to the use of WSS and show how they can be minimized and avoided. The base for this chapter is several feasibility studies, made in different types of buildings, and population surveys showing concerns about the user’s security. Studies about water quality in existing WSS are also presented, as well as important security measures presented in international legislation and standards. The conclusions allow us to understand if this question is being properly discussed (if all the main problems are being covered), which measures are being applied and if others are needed.