Energy Intensity Values Research Articles

An eco-efficient European metal industry transition towards Circular Economy

The European metal industry can minimize carbon and energy intensity through Circular Economy (CE) solutions in order to achieve the Agendas’ 2030; 2050 targets. This paper evaluates the eco-efficiency in 21 European countries using hybrid window data envelopment analysis (WDEA) across two scenarios. The study compares short- and a meso-term policies by choosing different window widths. Inputs include gross fixed capital formation (GFCF), labor force, and energy intensity value added, with value added as desirable output and carbon intensity value added as undesirable output. Results show that the meso-term policy yields an average eco-efficiency of 47%, while the short-term policy achieves 55%, suggesting that short-term strategies are more effective for the metal industry in reaching the Net-Zero goals. Geographically, Western and Northern Europe exhibit better eco-efficiency than Eastern and Southern Europe. In essence, the European metal industry can reach a Net-Zero status through deep CE transformations in energy and carbon intensity via cleaner production.

Energy Intensity Forecasting Models for Manufacturing Industries of “Catching Up” Economies: Lithuanian Case

The objective of this research was to construct energy intensity forecasting models for key manufacturing industries, with a particular focus on “catching up” European economies. Future energy intensity values serve as the foundation for energy demand forecasts, which are essential inputs for the analysis of countries’ decarbonisation scenarios. The Lithuanian case is analysed in the context of its efforts to reach the economic development level of the most advanced European Union (EU) countries. The scientific literature and energy policy analysis, interdependence (correlation and regression), tendency and case analysis, logical economic reasoning, and graphical representation methods have been applied. The energy intensity forecasts until 2050 were based on historical statistical data of value added and final energy consumption of EU countries from 2000 to 2021. The analysis of historical trends revealed a remarkable decrease in industrial energy intensity in most EU countries, including Lithuania. Given the rapid pace of decline in historical energy intensity, the values observed in individual Lithuanian industries have already reached levels comparable to the most economically advanced EU countries. Four econometric trendlines were employed to construct forecasting models for energy intensity. The results for Lithuania demonstrated that the selected trendlines exhibited a high degree of fit with historical energy intensity data from the EU, as evidenced by their R2 values. Furthermore, the forecasts were shown to be highly accurate, with their MAPEs remaining below 10% in most cases. Nevertheless, the logarithmic trendline was found to be the most accurate for forecasting energy intensity in total manufacturing (MAPE = 4.0%), non-metallic minerals (MAPE = 3.5%), and food, beverages, and tobacco (MAPE = 4.1%) industries, with the exponential trendline in the chemical industry (MAPE = 8.7%) and the moving average in the total manufacturing industry (MAPE = 4.0%), food industries (MAPE = 4.0%), and remaining aggregate industries (MAPE = 14.5%). It is forecasted that energy intensity could decline by 8 to 16% to 1.10–1.20 kWh/EUR in Lithuania’s manufacturing industries by 2050.

Performance Characteristics and Optimization of a Single-Stage Direct Air Capture Membrane System in Terms of Process Energy Intensity

The increase in emissions and concentration of carbon dioxide in the atmosphere necessitates the implementation of direct carbon dioxide capture technologies. The article presents the characteristics of a single-stage membrane unit for the direct capture of carbon dioxide from the air. A membrane with a selectivity of αCO2/N2=70 and permeability PCO2=108m3(STP)(m2·h·bar) is chosen as the reference variant. It is demonstrated that increasing the pressure difference in the system by reducing the pressure of the permeate stream results in an improvement of all analyzed parameters. Manipulating both the membrane surface and its CO2 permeability yields similar results. With an increase in permeability or membrane surface area, the proportion of CO2 in the retentate and permeate decreases, while the degree of carbon dioxide recovery increases. However, the energy intensity of the process is a complex issue due to the presence of a local minimum in the obtained characteristics. Therefore, a relationship between the constants of energy intensity values for the separation process on the surface area field and CO2 membrane permeability is presented. The minimum energy intensity of the process obtained is 22.5 kWh/kgCO2. The CO2 content in the retentate for all analyses did not exceed 280 ppm.

Structural, Mechanical, and Optoelectronic Properties of CH3NH3PbI3 as a Photoactive Layer in Perovskite Solar Cell

The structural, electronic, mechanical, and optical properties of pseudo-cubic CH3NH3PbI3 perovskite have been studied within the framework of density functional theory, in line with solar cell applications. The computed values of lattice and elastic constants concurred with the available theoretical and experimental data. This compound has a semi-conducting behavior, with a direct band gap of about 1.49 eV. Note that the solar radiation spectrum has a maximum energy intensity value of approximately 1.50 eV. Thus, semiconductors with such gaps are preferred for photovoltaic applications. Its elastic parameters reveal that it is a ductile material that is mechanically stable. Optical descriptors such as refractive index, reflectivity, extinction, energy loss, and absorption have been explored with the aim of establishing the optical features of the material. Our findings demonstrate that this perovskite is suitable for solar cell applications based on the size and nature of the band gap, as also supported by the obtained upper limit value of simulated power conversion efficiency via the spectroscopic limited maximum efficiency mathematical model.

Учет энергоемкости строительных материалов в течение жизненного цикла объектов капитального строительства

Considerable energy resources are consumed in the production of building materials, during construction and installation works, for operation with current and major repairs, reconstruction, dismantling, utilisation and recycling. As a rule, these energy resources are non-renewable, therefore, for energy saving purposes, it is necessary to take into account the total energy consumption of capital construction facilities during their life cycle. The authors have proposed the structure of a relational database of building materials energy intensity to calculate energy costs. The proposed database contains a list of building materials and energy intensity values at all stages of the life cycle. The novelty of the database is the division of materials by building elements (replaceable, non-replaceable). The article presents fragments of energy intensity calculation of the apartment building life cycle in the Ivanovo city using the proposed database.

Градиентная модель адгезии жидкости на поверхности строительного материала

Considerable energy resources are consumed in the production of building materials, during construction and installation works, for operation with current and major repairs, reconstruction, dismantling, utilisation and recycling. As a rule, these energy resources are non-renewable, therefore, for energy saving purposes, it is necessary to take into account the total energy consumption of capital construction facilities during their life cycle. The authors have proposed the structure of a relational database of building materials energy intensity to calculate energy costs. The proposed database contains a list of building materials and energy intensity values at all stages of the life cycle. The novelty of the database is the division of materials by building elements (replaceable, non-replaceable). The article presents fragments of energy intensity calculation of the apartment building life cycle in the Ivanovo city using the proposed database.

Modeling and Performance Projections of a Dual-Purpose CO2 Capture and Energy Storage Device from Oceanwater

Carbon dioxide (CO2) capture and removal technologies are critical to limit global warming to 2 °C in the next few decades. In addition to the atmosphere, the oceans are large carbon sinks and have to-date captured about 25% of all anthropogenically released carbon. Therefore, ocean water CO2 capture can complement Direct Air Capture (DAC) technologies. To harness this source of CO2, this talk proposes, models, and analyzes the performance implications of a reversible, aqueous electrochemical flow device, which uses hydrogen and redox salt looping to achieve pH shifting. The reversible nature of this device enables its use in both power production and consumption modes, enabling CO2 capture to be powered exclusively by variable sources of renewable electricity. To model the performance of the proposed energy storage and CO2 capture device, we developed an equivalent circuit model to predict the current-voltage performance of this device mediated by ferricyanide/ferrocyanide and H2. Performance predictions are modeled as a function of key transport and thermodynamic conditions, specifically, for different mass transport rates of gases and aqueous electrolytes and different extents of pH shift between acidification and basification steps. Estimations of device performance are developed at both laboratory-scale and industrially relevant current densities. Modeled electrochemical energy intensity values of the overall device operation are compared to current state-of-the-art electrochemical ocean CO2 capture technologies to show the approach’s potential. Overall energy intensities are compared to current state-of-the-art DAC technologies. Our results show the energy intensity for CO2 capture during the reversible process has the potential to be reduced compared to present day DAC systems, but is highly sensitive to parasitics, ohmic losses, and the extent of competing reactions. Additionally, projections of the device energy-time profile are demonstrated to show the diurnal energy storage potential, specifically with applications to solar energy. Energy storage capabilities in the proposed device provide additional benefits of powering this CO2 capture device with renewable electricity while providing flexibility to manage grid-scale electricity demand. Overall, a reversible, pH-shifting based oceanic CO2 capture device offers holistic benefits from designing CO2 capture to operate exclusively from renewable electricity.

Drivers of global carbon emission changes: A heterogeneity perspective of decomposition and attribution analysis

Due to the differences in economic development, resource endowment, and historical accumulation, different types of countries have significant technical heterogeneity in carbon emissions. Identifying the driving factors of carbon emission changes, under the premise of distinguishing national heterogeneity, can provide a basis for the formulation of the “Differentiated Responsibilities” emission reduction policies. Therefore, this study introduces the idea of Meta-frontier into the traditional production-theoretical decomposition analysis, and constructs a new influencing factor analysis framework. Based on the newly built method, the empirical study of 60 representative countries draws the following three meaningful conclusion: 1) Different types of countries have obvious heterogeneity in technology, efficiency and change trend of energy use. Specifically, countries with higher energy intensity values generally have a quicker decline rate than those with lower energy intensity values. There exists “catch-up” effects for the backward to the advanced countries. 2) Decomposition results show that potential energy intensity (PEI) is the dominant factor reducing carbon emissions, especially for those large economic output with large energy consumption (Group-L) countries (0.604). Economic activity effect (ECA) is the most significant driving force for countries with small economic output and small energy consumption (Group-S), reaching 1.806. Meanwhile, the attribution results showed different characteristics in different groups of countries. The impact of various factors that reflect the heterogeneity of production process on carbon emissions mainly comes from the contribution of Group-L. 3) We suggest that, in the process of carbon reduction, large energy consumption countries should pay more attention to the gap between the development and speed of the world’s cutting-edge technologies.

Decarbonisation of heat: Analysis of the potential of low temperature waste heat in UK industries

The UK will need to decarbonise low temperature industrial waste heat (up to ≈250 °C) to achieve net-zero greenhouse gas emission targets. Industrial waste heat production represents an opportunity for reduction in the use of primary fuels used in the production of commodities. Energy inefficient processes in addition to increased emissions raises the cost of plant operation, – an undesirable scenario for both industrial competitiveness and the environment. Less is known about the quantity and potential applications for recovered low temperature industrial waste heat in UK and the quantification and characterisation of the resource can provide the needed impetus for the development and adoption of green technologies to help achieve the 2050 Net-Zero target. In this work the potential magnitude of the low temperature industrial waste heat resource in the UK is analysed by using sector-level energy intensity values for different industries while drawing on corresponding estimates from previous studies in the USA and by closely mapping the UK Standard Industrial Classification (SIC 2007) against sectors in the USA (NAICS [North American Industry Classification System]). The assessment undertaken finds that the recoverable potential of low temperature waste heat up to ≈250 °C could be up to 83.7% of the total estimated waste heat potential in UK industry. Significant opportunities exist in this low temperature range for waste heat recovery actions at individual sites. Research and Development (R&D) into alternative improved methods for waste heat recovery, storage, and use (WHRSU) technologies could also produce significant positive environmental and industrial impact.

Does Clean Energy Use Have Threshold Effects on Economic Development? A Case of Theoretical and Empirical Analyses from China.

Increasingly serious energy security and environmental problems have become the main constraints to China’s economic development. Therefore, it is critical to explore the threshold effect of clean energy use on China’s economic growth. Based on the panel data of 30 Chinese provinces from 2000 to 2019 and using energy intensity (EI) as the threshold variable, this study adopts a panel threshold model to explore the threshold effect of clean energy development on the economy. Empirical results indicate that clean energy has a significant threshold effect on economic development, with the threshold value of EI being 0.7655. When EI is less than 0.7655, clean energy development has a more positive effect on economic growth. When the EI exceeds 0.7655, the impact is significantly positive but with a smaller coefficient. EI weakens the role of clean energy development in promoting economic growth. After 2015, the EI of most provinces in the sample was below the threshold value, which indicates that in recent years, with the economic cost of developing clean energy decreasing, the role of clean energy development in promoting the economy has become more significant. Therefore, we propose policy implications to better promote the effect of clean energy development in promoting economic growth.

Energy–water nexus of formal and informal water systems in Beirut, Lebanon

Abstract Many areas in the world with chronic and intermittent water shortages rely on informal water systems for much of their daily water needs with water from tanker trucks, purchased bottled water, rainwater cisterns, or pumped well water. These alternative sources all require varying amounts of energy. Water–energy nexus studies have not yet considered environmental impacts of informal water sources, specifically from an energy intensity and carbon emissions perspective. This study compares energy use and carbon emissions per cubic meter and per capita for both formal and informal water sources for a neighborhood in Beirut Lebanon. Energy use and carbon emissions are calculated for three delivery stages per source including pumping, treatment and distribution. The results show that informal sources have the highest energy use and carbon emissions. From the total water delivered to households, they account for 83% of energy use and 72% of carbon emissions per capita, even though they only provide 23% of total delivered volume per capita. Bottled water and distribution of water by tanker trucks have the highest energy intensity values per cubic meter of all water sources. Moreover, internal building water pumping, which is not typically accounted for, takes up to 14% of total energy use and 23% of total carbon emissions per capita compared to other water sources. To address model uncertainty, we conduct a sensitivity analysis, showing that the base model presented reasonably stable results and identifying the most sensitive parameters for further research. While informal sources help communities overcome water shortages they result with negative impacts. Strategies are proposed to improve the environmental performance of the Lebanese electrical grid, reduce water losses, replace inefficient truck engines and incentivize household to invest in low carbon technologies.

Implementation of "Intellectual networks" – direction of ensuring the energy efficiency of the national economy of Ukraine

At the present stage of development of the world economy and almost all countries’ national economies, the problem of energy saving and energy efficiency rises. In developed countries, the solution to this problem depends not only on reducing energy consumption but also on the introduction of new innovative processes in power supply systems and energy systems. In particular, there is a growing interest in the modernization of energy systems in the world in recent years based on a new concept called Smart Grid ("intelligent power system"). The problem of energy efficiency is especially relevant for Ukraine, which has the highest value of energy intensity of gross domestic product, and the country's energy system is characterized by extremely high losses of electricity in the grid. The largest consumers of electricity in Ukraine are large industrial enterprises, where the high energy intensity of production is caused by the depreciation of fixed assets; lack of incentives to implement energy efficiency measures and of a systematic approach to energy consumption; lack of financial resources for the implementation of energy efficiency measures. Issues of identifying the problems of energy efficiency of the economy and ways to solve them are set out in the scientific works of such researchers as S. M. Baliuta, O. S. Bykonia, A. Yu. Danilkova, Ya. V. Krutohorskyi, O. O. Liakhova, Yu. T. Matvieieva, H. H. Pivniak, S. V. Sapozhnikov, O. V. Fedirets, V. O. Shvedun. Without diminishing the results of the previous research, it should be noted that a number of problematic issues on this topic are still studied insufficiently, which determines the relevance of the research topic. The aim of this research is to assess energy efficiency as a factor of the competitiveness of Ukraine's industrial products, justify the main reasons for the high energy intensity of GDP in Ukraine, and the necessity of innovative direction for the future development of energy through the implementation of "smart grids". Analysis of the energy sector’s current state and development has shown that the problems in the power industry today can not be solved only by extensive capacity-building of grids and increasing the number of electrical equipment. A new direction in the future development of energy is the implementation of smart grids ("Smart Grid"). The domestic national economy has problems with energy efficiency and energy saving. The solution to these problems lies in the field of implementing energy management and audit, studying and using foreign experience in the development of intelligent energy.

The cost-effectiveness of energy savings through water conservation: a utility-scale assessment

It is well-established that water infrastructure systems require energy to treat and deliver water to end-users. This fundamental relationship presents an opportunity to secure energy savings through water conservation. In a previous study, the energy savings linked to a statewide water conservation mandate in California were found comparable in both resource savings as well as cost-effectiveness to the energy savings achieved directly through energy efficiency programs. This study pursues a similar line of inquiry, but at the scale of an individual city as opposed to a statewide assessment. Los Angeles, California, serves as the case study for estimating the energy savings secured through water conservation programs relative to energy efficiency (EE) programs enacted in the study region. We apply three different estimates of energy intensity (EI) for the conversion of water savings to energy savings. These applied EI scenarios are differentiated by scale and system boundary, including: a direct assessment of EI within the water utility service territory, an expanded boundary that includes imported water infrastructure systems, and a broader, top-down estimate for the regional hydrologic zone. Across all scenarios, the estimated energy savings secured through water conservation programs prove to be cost-competitive with the energy efficiency programs enacted by the utility. When using estimates of EI with expanded system boundaries that include the upstream energy embedded in imported water supplies, water conservation becomes a significantly more attractive pathway for saving energy. This outcome underlines the importance of clearly defining the water-energy system boundary of interest, both to determine an accurate EI value, and subsequently, to design and implement cost-effective programs that jointly conserve both water and energy resources.

Optimization and design of energy monitoring system in fuels terminal: a case study in North Sumatera province of Indonesia

Optimization of energy use in the PERTAMINA’s fuel terminal (TBBM) was carried out by the Energy Audit method. The data obtained during energy audit activities then processed to carry out the Energy Performance Indicators (EnPis) which produces Specific Energy Consumption (SEC) and energy baselines. The energy cost center that creates a web-based energy monitoring system is carried out to facilitate monitoring and control and will become supporting tools. The information provided from the energy monitoring system displays the profile of total energy consumption, distribution of energy consumption, the energy consumption of equipment in production facilities in the form of daily, monthly, and annual data. Energy intensity and baseline values obtained from energy consumption and production data for the past several years will be the target and warning system to maintain energy usage that exceeds reasonable limits. The results obtained by the value of energy intensity of 0.0023 GJ / KL, while the total emissions generated from energy consumption amounted to 1,144.4 tons-CO2 / year. 51% of energy is used for production facilities and the rest is used for supporting facilities. The use of electricity as well as thermal energy does not have a strong correlation with the level of fuel sales throughout the year and the use of NGS (New Gantry System) technology does not show a significant decrease in energy intensity, where IKE values fluctuate throughout the year. This reinforces the need for continuous and real time energy monitoring. By implementing the potential for energy savings, an energy use optimization is obtained by reducing energy consumption by an average of 10% - 15% per month or as much as 18,057 - 27,086 kWh per month, equivalent to 25 - 38 million rupiah per month.

Data-driven estimation of building energy consumption with multi-source heterogeneous data

For better energy evaluation and management, a categorical boosting (CatBoost)-based predictive method is presented to accurately estimate building energy consumption by learning large volumes of multi-source heterogeneous data collected from buildings. To be specific, the newly-developed CatBoost model belonging to the ensemble learning has superiority in handling categorical variables and producing reliable results. As a case study, our proposed method is validated in a multi-dimensional dataset about Seattle's building energy performance provided by the city’s government, aiming to estimate the weather normalized site energy use intensity of buildings and characterize its non-linear relationship with other 12 possible influential features. Results from the 5-fold cross-validation demonstrate that the model exhibits a strong ability in predicting the exact value of energy intensity precisely, which can even outperform popular machine learning algorithms including random forest and gradient boosting decision tree under R2 of 0.897. Based on a defined threshold, these predicted values can be classified as the normal or abnormal energy consumption reaching an accuracy of 99.32% for outlier detection, which is helpful in alarming potential risks at an early stage and developing strategies to enhance the energy efficiency. Moreover, results from the established model can be interpreted objectively, suggesting that features concerning the physical and energy characteristics contribute more to energy estimation than environmental features. Since such results understand the building energy consumption and efficiency in a data-driven manner, they can eventually serve as guidance for building owners and designers in designing and renovating buildings to achieve better energy-conserving performance.

Ensuring the Environmental Safety of Coal-fired Power Plants for the Flue Gases Purification

The article is devoted to solving of the pressing issue–provision of ecological safety of urban areas in flue gas purification of coal power plants and boiler houses. Use of the method for evaluating and selecting the maximum ecological efficiency and energy intensity value of purification of exhaust gases of thermal power plants and boiler houses of municipal services within the known physical and energetic approach allowed to obtain the parametric dependence of ecological efficiency and energy intensity value and determine the optimum parameters of hydrodynamic cleaning process with further designing of a new technical solution.On the basis of the simulation process and cleaning systems a new device of hydrodynamical (wet) cleaning the flue gases via control parameters significantly affecting the ecological efficiency and energy intensity value of the cleaning process was worked out. Moreover, control of parameters is carried out at the design of flue gases cleaning system, which allows to significantly optimize the choice of ways and means of reducing air pollution in urban territories. The obtained simulation results can be used to develop new or improve existing devices of hydrodynamic flue gases purification.

Quantifying water-energy nexus for urban water systems: A case study of Addis Ababa city

The complex interdependency between water and energy poses new challenges for policymakers to achieve a safe, secure, and sustainable supply of water and energy in the future. The water-energy nexus can be typically characterized by efficient use of energy and water resources. Hence, this paper aims to explore quantitative results of the nexus in terms of energy intensity on existing water systems within urban water cycles. The energy requirement for water treatment and water conveying to the city (from Legadadi water treatment, Gefersa water treatment and wastewater treatment area) as well as the energy requirement for water distribution within the city were quantified. The energy intensity for groundwater extraction, water transmission and water distribution were computed using Energy Intensity method. This led to identify the best technologies to insure the security of water-energy nexus. The annual energy demand and energy intensity values for groundwater extraction were estimated to be 0.6 PJ and 1.2 kWh/m3 respectively. These values for operating all pumps in the water transmission were 0.13 PJ and 0.32 kWh/m3 respectively. Similarly, the energy intensity value for water distribution was 0.27 kWh/m3 and distributes water to residential, commercial and industrial end-users. Determining the energy intensity predicts the future energy demand in urban water system. In 2030 and 2050, the predicted energy demand will be 0.50 and 0.83 PJ respectively for water transmission whereas it will be 0.41 and 0.67 PJ for water distribution.

Neural networks application in managing the energy efficiency of industrial enterprise

The article is devoted to the creation of a method for using of neural networks approach in solving problems of energy efficiency management at the industrial enterprise. The method allows to obtain an approximate expected value of the energy intensity of production, depending on the values of the main factors affecting it. The multilayer perceptron was chosen as the type of neural network, synthesis of which was carried out by using the genetic algorithm. When sampling for the synthesis of a neural network, we used the results that were obtained by means of a priori ranking, correlation and regression analysis based on the statistical data of industrial enterprises in machine-building profile. The recommendations of the use of the method and the application of its results in the practical implementation at the industrial enterprise are given. Calculations based on the aforementioned method ensured a high precision of prediction of energy intensity values for industrial enterprises that were included in the sample during the synthesis of the neural network, and an acceptable error while testing on industrial enterprises from a test sample.

Investigating environmental Kuznets curve from an energy intensity perspective: Empirical evidence from China

This study pioneers investigating the environmental Kuznets curve (EKC) hypothesis and its possible regional differential characteristics in China. Based on 2003–2017 years of provincial panel data, this research employs panel smooth transition auto regression (PSTR) model to analyze the impact of income levels on environmental pollution and identify the EKC threshold of energy intensity. Then, 30 Chinese provinces were categorized by energy intensity to examine the inter-provincial and interregional differences in the EKC threshold of energy intensity, rather than the traditional threshold of income. The results indicate that China's pollution emissions and energy intensities show a stepwise decreasing pattern from the western region to the eastern region. In addition, the impact of income levels on pollution emissions is non-linear, and the critical value of energy intensity is 0.9168 between the high- and low regimes. An inverted U-shaped environmental Kuznets curve is accepted for energy intensity, with 0.7670 as its threshold value. When the energy intensity is higher (lower) than the threshold value, the income elasticity of pollution emission is positive (negative). The more developed provinces and municipalities mainly in the eastern region are proved to exceed the threshold than the provinces in the central and western regions within the sample period. Given these findings, this study further divides China's provinces into eco-friendly, low-pollution, and high-pollution provinces, and accordingly, the most important policy recommendations were discussed for policy-makers and researchers. This research can provide a new insight to investigate countries with unbalanced development levels within and a reference for environmental governance policies in sub-regions.

Life-cycle assessment and life-cycle cost analysis of decentralised rainwater harvesting, greywater recycling and hybrid rainwater-greywater systems

Decentralised rainwater harvesting (RWH), greywater recycling (GWR), and hybrid rainwater-greywater systems (HRG) mitigate urban water scarcity at both domestic residential dwelling and commercial building scales. However, few studies have been conducted on HRG in mixed urban water provision schemes under tropical climatic conditions. Thus, this study evaluates and compares the environmental and economic impacts of a centralised mains water system (MWS) against a decentralised RWH, GWR and HRG at a domestic and commercial building using life-cycle assessment (LCA) and life-cycle cost (LCC) analysis under tropical climatic conditions. A functional unit (FU) of 1 m3 of non-potable toilet flushing and irrigation water for a project lifespan of 50 years was used. Results indicate that CML 2001 and TRACI 2.1 methods produce similar results. LCA and LCC indicate that the optimal systems are the commercial HRG and domestic RWH. The commercial HRG has the highest mains water savings (55.3%), lowest environmental impact scores for seven categories, and is the second fastest system to become financially attractive at USD5.20/m3. Similarly, the domestic RWH has the second highest mains water savings (95.3%), lowest environmental impact scores relative to a MWS for seven impact categories, and is the first system to become financially attractive at USD2.00/m3. Sensitivity analysis revealed that global warming, water stress index, and eutrophication are most sensitive to a ∓20% variation in GW and RW energy intensity values at commercial and domestic buildings, respectively. The financial viability of decentralised RWH, GWR, and HRG systems increase with increasing discount rate and mains water tariff, as well as decreasing electricity tariff and installation factor. Financial incentives and subsidy schemes from the Malaysian government may promote uptake of decentralised water systems for mixed urban water provision, as none of the systems were financially attractive otherwise at a discount rate of 6% for 50 years.