Alternative water supply systems to achieve the net zero water use goal in high-density mixed-use buildings

Promoting Water Efficiency in a Municipal Market Building: A Case Study

“…Based on the water-end uses data, either of the proposed water-saving scenarios has potential water savings: from 28.4% (scenario 1) to 74.4% (Scenario 4). If only scenarios 1 and 2 were implemented in the majority of the public and commercial buildings in the region, a reduction in the pressure on local freshwater ecosystems and resources [49,50], in energy consumption (both in public water supply and wastewater treatment systems) and CO 2 emissions [2,6,7,9,10,42,[51][52][53][54] would undoubtedly occur. Although determining water end-uses is the crucial starting point for implementing water sustainability measures, no water end-uses were measured in any research concerning the installation of RWHS in commercial buildings cited in the present research.…”

“…This consequence of climate change is more notorious in regions or countries experiencing water scarcity and shortage [4], such as southern Europe and the Iberian Peninsula [5,6]. Since buildings are one of the highest consumers of potable water globally [7], the urban water cycle is affected by climate change [8], but it also contributes to it. Indeed, water potabilization processes, water delivery to consumers, and wastewater treatment use significant amounts of energy, contributing to increasing CO 2 emissions [2,[8][9][10][11].…”

“…The optimization of water management can be achieved by implementing two main categories of solutions: (i) reducing water consumption through the adoption of efficient products or devices (e.g., flushing cisterns, taps, and showers), reducing the water waste and loss [2,7,10]; (ii) identification of new water sources, allowing to reduce the pressure on traditional water sources, when drinking water quality is not required [4,7,8,[13][14][15][16], these including rainwater harvesting systems (RWHS) and grey water reuse, can be operated at the onsite scale, cluster scale, or distribution systems [7,15]. According to a review on [7], research has demonstrated that grey water reuse is economically attractive as an alternative water supply system for single housing in a water-stressed region, and the cost of water is high. Conversely, when considering commercial buildings, RWHS can be more effective in reducing water consumption and may include lower related costs and technological complexity during the installation and operation [4].…”

Economic and Reliability Assessment of Hybrid PRO-RO Desalination Systems Using Brine for Salinity Gradient Energy Production

“…Therefore, the carbon tax and emission factor are used to determine the carbon emission cost, which also depends on the country where the plant is located. Additionally, the carbon emission cost is a function of energy consumption [24,41,42], as shown in (14).…”

“…The hourly power demand (P WD (t)) of the RO desalination unit depends on the specific energy consumption (SEC) to produce 1 m 3 of freshwater and the actual volume of water (QW RO (t)) produced per hour [44,45]. The SEC of a conventional RO system ranges between 3 and 6 kWh/m 3 , but a hybrid with PRO reduces this energy requirement to 1.2 kWh/m 3 [41].…”