Optimising water demand estimation in non-residential buildings: A new design flow rate approach

A prerequisite for achieving high energy efficiency of water supply systems (understood as using less energy to perform the same task) is the appropriate selection of all elements and their rational use. Energy consumption in water supply systems (WSS) is closely connected with water demand. Especially in the case of oversized water supply systems for which consumers’ water demand is at least 50% less than previously planned and flow velocity in some parts of the system is below 0.01 m·s−1, this problem of excessive energy consumption can be observed. In the literature, it is difficult to find descriptions and methods of energy management for such a case. The purpose of this study was both an evaluation of the current demand of an oversized WSS and a preliminary technical analysis of the possibility for energy saving. Solutions are presented that resulted in improvements in energy management, thus increasing energy efficiency. The conducted analyses indicate the wide use of numerical, hydraulic models, among others, for the needs of the sustainable oversize water supply systems management in order to improve energy efficiency. Those simulations only give energy consumption results as a first step in the process of decision-making for the modernization process, in which investment costs should be taken into account as a second step. Thus, this paper emphasizes the crucial role of hydraulic models as a good analytical tool used in decision support systems (DSS), especially for large, oversized water supply systems.

The building water supply system is a fundamental unit in water supply systems as it is directly associated with end users. However, the studies available on its efficient design are limited. Water demand estimation continues to be an important issue in water supply systems' design because of its multifaceted nature. Hunter's curve, or Fixture Unit method, is widely used for estimating the load on plumbing. Regardless of its popularity, it has a few drawbacks and is arbitrarily modified in some plumbing codes. Fixture-use probability, a basic entity in the Fixture Unit and some other methods, is a difficult parameter to estimate. Commonly, high-resolution field data is used for stochastic modelling of residential water demand which may not be always available. The paper reviews important residential water demand models in view of their applicability in building water supply system design. The irregular nature of water demand in buildings is due to uncertainty in water-use behaviour of users at fixture level. Use of soft-computing techniques can provide an advantage over the other methods in modelling such behaviour. The paper also discusses reliability of building water supply systems and applicability of some common indices for estimating reliability of building water supply systems.

The purpose of this study is to organize the history of urban water use in Tokyo with focusing on two water sources: surface water and groundwater. The urban water supply-demand space in Tokyo shifted from a three-dimensional structure, including underground space, to wide-spread and two-dimensional one, excluding underground space. To foster sustainable urban water supply systems, efforts are needed to both avoid an increase in water demand and maintain local groundwater resources. Moreover, in terms of water security, at the time of disaster or water shortage, sustainable urban water supply systems should include both large-scale extensive water supply systems and locally distributed water supply systems to supplement each other.

The installation of water efficient appliances is an efficient demand-side water management measure favored by policymakers and water providers nowadays. The adoption of low flow showerheads in large and complex plumbing systems will not only contribute to a great reduction of shower water use in the whole water system, but also further influence the water supply system design. Hence, it is necessary to justify the redesign of existing water supply systems (such as the pipe size, storage tank volume, pumping arrangement etc.) in terms of the use of low flow showerheads. This study uses Monte Carlo simulations to evaluate the design flow rate for a typical high-rise roof tank water supply system in Hong Kong with the installation of low flow showerheads. The simulation results indicate that a full installation of low flow showerheads can decrease the design flow rate by 15%, corresponding to an energy efficiency improvement of 1.5%. The potential for water savings and associated energy savings can be significantly higher when all installed appliances in homes are water efficient (e.g., showerheads, water taps, washing machines). Further work is required to evaluate the redesign of existing water supply systems for a sustainable future.

The rapid expansion of urban infrastructure has significantly increased the demand for efficient and reliable water supply systems in multi-storey buildings. This study, titled “Study and Design Analysis of Water Supply System in Multi-Storey Building,” presents a comprehensive evaluation of hydraulic performance and system design to ensure adequate water distribution across all floors. The research focuses on estimating water demand based on occupancy and standard per capita consumption, followed by the systematic design of key components such as overhead storage tanks, pipeline networks, and pumping arrangements. Hydraulic analysis is carried out using fundamental engineering principles, including pressure head evaluation, flow characteristics, and frictional loss assessment through the Darcy–Weisbach approach. A detailed investigation of pressure variation at different elevations is performed to ensure sufficient and uniform water supply without excessive pressure that may lead to system failure. The study also examines the influence of pipe diameter, velocity, and friction losses on overall system efficiency. Results indicate that improper selection of design parameters can lead to significant energy losses and inadequate supply at higher levels. The findings of this study contribute to the development of a safe, cost-effective, and optimized water distribution system for multi-storey buildings. The proposed approach not only enhances hydraulic efficiency but also supports sustainable urban infrastructure development by minimizing water losses and improving system reliability. Keywords: Hydraulic Analysis, Pressure Distribution, Head Loss, Darcy–Weisbach Equation, Pipe Flow, Friction Loss, Water Demand Estimation, Overhead Tank Design, Flow Characteristics, Sustainable Water Management.

ABSTRACTThe precise estimation of water demand at large‐scale irrigation perimeters is a key requirement for water management. Most methods for estimating water demand use biophysical models and cropping patterns but do not account for the wide range of actual farming practices. As a result, these methods only allow estimation of theoretical water demand. The objective of this study was to analyze different methods for evaluating irrigation water demands using several levels of knowledge about irrigation perimeters such as crop water requirements, cropping pattern, irrigation techniques, and water application depths (WAD). Most of this knowledge was related to farming practices, which can vary. Farm typology is an appropriate way to account for the variability in farming practices. These methods were applied in an irrigation scheme in northern Tunisia. The perimeter was subdivided into two sectors: the first sector was designed for surface irrigation and the second for sprinkler irrigation. The first method estimated water demand at the scheme scale based on actual cropping patterns and assuming that farmers used the planned irrigation techniques and satisfied plant water requirements (L1). However, the farmers did not use the planned irrigation techniques. Instead, they combined surface, sprinkler, and drip irrigation techniques depending on the crops they were growing.The second method examined current irrigation techniques using the results of farm typology that provided the areas under each crop irrigation system (L2). The two methods provided a theoretical water demand model at the scheme scale. However, water demand also needed to account for actual WADs (L3). Field surveys were performed to evaluate the WAD of each crop irrigation technique. Methods L1 and L2 showed similar estimations of water demand at the scale of the perimeter, and the savings in water obtained by converting to drip irrigation were balanced by a reduction in sprinkler irrigation due to conversion to surface irrigation. In contrast, the L3 method estimated 50% lower water demand than that provided by L1 or L2, since the supply of water was insufficient. The irrigation network was designed 50 years ago and no longer corresponds to the needs of current farmers. Farm typology was also shown to be a method that accounted for farm diversity; water demand estimated based on typology differed by only 5% from that obtained by summing the needs of individual farms. Copyright © 2011 John Wiley & Sons, Ltd.

In Romania, there are more than 13,000 localities of which only 10% are equipped with centralized water supply systems at European standards. In the western area of Romania, there is a district operator, which manages the water supply and sewerage systems. It started working on upgrading and rehabilitating water supply systems by accessing European funds, to meet the quality requirements imposed by European legislation. In the first stage, 15 water supply systems were refurbished with works performed in urban and rural parts of western part of Romania. In the second and third stages, investments will continue for the rehabilitation and upgrading of all the western localities, which do not meet the quantitative and qualitative conditions of potable water with European standards. Water resources need to be managed very well, especially in the context of climate change, with water sources having to provide ever growing flow to consumers. The paper shows what are the problems of the centralized water supply system of three localities in western Romania, and how we resolved them. The aim of the study is to analyse the efficiency of the current water supply system and to identify the causes that lead to the qualitative deterioration of drinking water distributed to consumers in populated centres. Laboratory determinations for samples of treated water were performed. Based on these laboratory determinations, corrections were made to ensure that the drinking water complies with current regulations (458/2002 Drinking Water Act and completed with Law 311/2004). The retrofitting and rehabilitation of the existing water supply system of the locality resulted on the basis of these analyses. The flow captured from underground source should be increased. To ensure the flow of water to consumers, the existing drilling and extension of the capture front will be rehabilitated. Rehabilitation of the water supply system will bring a real benefit in terms of quality of life according to environmental restrictions under Directive 98/83 / EC.

Stochastic models for estimating residential water demand use high-resolution field data consuming large costs and significant time. An attempt for the accurate estimation of water demand may result in its complex analytical model due to numerous factors affecting the water use event. Moreover, as the water supply system is always subjected to variations in demand, the accuracy of water demand estimation in its design can be side-lined. The water demand in residential buildings is mainly governed by the users’ characteristics and their daily schedule. In this view, the use of Fuzzy Logic can be advantageous to model the uncertainty in water demands. The presented study attempts to provide a methodology to estimate urban indoor residential water demand with the help of user-based end-use models in the absence of field data and generate various possible water demand patterns of fixtures. Usergroups were created for assuming spatial variations in water demand. Fuzzy Logic was used to develop the end-use models using data on urban users’ characteristics, their diurnal activities, and water use habits to estimate the demand characteristics of fixtures. The model may also facilitate the computation of pipe sizing in building water supply systems.

This review paper explores integrating renewable energy into water supply systems as a critical strategy for addressing global challenges such as climate change, energy scarcity, and water security. By comparing initiatives in African countries and the United States, the study highlights the importance of sustainable, efficient, and resilient water supply systems in diverse geographical and socio-economic contexts. The paper examines the technological, financial, policy, and infrastructure challenges and opportunities that influence the adoption of renewable energy in the water sector. It delves into the sustainability and scalability of renewable energy-powered water supply initiatives, assessing their environmental, economic, and social dimensions. The comparative analysis reveals lessons learned, best practices, and potential areas for collaboration between the regions. Future directions are proposed, emphasizing the need for international cooperation, knowledge sharing, and innovation to enhance the integration of renewable energy into water supply systems. The paper concludes by underscoring the pivotal role of renewable energy in achieving sustainable development goals, particularly in ensuring access to clean water and energy for all.
 Keywords: Renewable Energy, Water Supply Systems, Sustainable Development, Comparative Review.

Assessing the significance of climate and community factors on urban water demand

The water resources management may face serious challenges under climate change. In order to efficiently utilize water resources and reduce loadings on centralized water supply systems, it is necessary for each water user to reduce their water requirements. Rural community consumes the great portion of water resources in Taiwan due to high irrigation water demands and thus is concerned in this study. The rural community considers having both external domestic water supply and irrigation systems, and installing reuse system and constructed wetland to provide harvested rainwater and reclaimed water. The purpose of this study is to establish an integrated water resources system dynamics model and propose indicators for quantitatively evaluating the water supply system of a rural community. The three indicators are designed to evaluate water saving efficiency, tolerance of drought duration, and influence of insufficient irrigation water on crop yields. The results show that the combination of the constructed wetland and reuse system possesses more eminent stability than the reuse system alone. The integrated water resources system may reduce up to 32 % of domestic water demands and 7.8 % of irrigation water demands from external systems, respectively. At the same time, the domestic system owns higher resilience. In conclusion, the results indicate that the reuse system and constructed wetland can significantly improve the stability and resilience of water supply system. The study on integrated water resources system for rural community desires more researches. Besides, the influence of climate change and water quality of reclaimed water should be further considered.

Experts and managers in the water supply sector are often challenged with a lot of different variants of obtained solutions for various types of water supply systems. Nowadays, in addition to meeting the technological and economic criteria, it is necessary to meet other criteria, such as environmental, social, political and other. Among other procedures, multi-criteria methods are used for the solution of such issues. This paper will present the use of the multi-criteria method Promethee for the case of technological criteria. The purpose of this is finding a technologically most appropriate variant of the observed water supply system, given that the resulting solution variants differ according to the size of certain parts. In addition, this paper explains the scientifically innovative and, in view of engineering, applicable methodology for dimensioning the sustainable urban water supply system driven by solar photovoltaic (PV) energy, which then becomes Energy Sustainable Urban Water Supply System (ESUWSS).

Achievement of Millennium Development Goals (MGDs) for water and sanitation requires significant investment, effective management, and participation of all stakeholders. This is especially highly challenging in low-income countries where utility inefficiencies due to limited infrastructure and absence of effective management system are still most prevalent. The problems of inadequate water and sanitation service provision in cities of developing countries are exacerbated by high growth rate in urban population. The proportion of the world’s population that lives in urban areas has increased from 43% in 1990 to 50% in 2008 (UNICEF/WHO, 2011). Asmara is the capital of the state of Eritrea and the administrative centre of the Central Region, and Asmara Water Supply Department (AWSD) is the only public utility responsible for water and sanitation services in the city and surrounding areas. Similar to most public water utilities in sub-Saharan Africa, AWSD has been facing financial and technical constraints due to an inefficient management and operation systems resulting from lack of qualified personnel, low tariffs, high non-revenue water (NRW), over staffing, poor consumer records and inefficient billing and collection practices. The problems were further exacerbated by the limited available water resources, aging infrastructure, lack of human resource development program, and lack of an effective planning and management system. This study aims in building a system of performance measurement, monitoring and analysis, and benchmarking practices to promote development of decision support tools to improve the management and operational process of the utility. The analysis of selected performance indicators showed that the water services provided by the water utility were unsatisfactory due to various factors such as, low service coverage, intermittent mode of water distribution, long-period of cut-offs, and poor management and customer care services. The results of this study emphasize the urgency of wide-ranging reforms needed by the decision makers in Asmara in order to achieve effective, efficient and sustainable water supply system.

Powering an island system by renewable energy—A feasibility analysis in the Maldives

"Design and Analysis of Water Distribution System" focuses on developing an efficient water supply system for rural areas, particularly in regions with limited access to clean and safe water. The project aims to optimize water distribution, maintain water quality, and address issues like water loss and inadequate pressure within the network. Using advanced software such as WaterCAD, the project analyzes the water demands of selected villages in Malshiras Taluka, Maharashtra, India, and designs a system to meet these needs. Key design elements include population forecasting, water demand estimation, hydraulic modeling, pipe sizing, pump selection, the construction of elevated service reservoirs, water distribution network. The towns' water supply network is analysed and developed using Bentley's WATERCAD programme. Water distribution network systems are designed to distribute water from a source to all or any single user in a sufficient amount, quality, and pressure. The project employs both conventional and advanced methodologies for water treatment, distribution, and optimization to ensure a reliable and sustainable water supply for the region through 2054.