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Network investments and projected energy prices greatly impact the financial viability and environmental impact of fifth-generation district heating and cooling (5GDHC) networks. Compared to the previous generation, the upfront investment costs in 5GDHC networks are relatively high due to the decentralized energy demand and supply of the participating prosumers. The transition to 5GDHC is also hindered by uncertain energy markets and the fluctuating energy demands of the prosumers. It makes investors hesitant to commit, even for promising business cases. In this work, a framework is presented to assess the economic and environmental performance of a 5GDHC business case, based on a multi-objective robust optimization algorithm (MO-RDO), to identify the optimal trade-offs between environmental and economic designs. The proposed methodology consists of four steps. In the first two steps, a specific business case is modeled, and techno-economic and environmental performances are analyzed against uncertain energy markets. In the third step, the techno-economic and environmental indicator responses are used to develop a data-driven machine-learning model. This model offers better computational efficiency than a high-fidelity nonlinear model and assesses the most influential parameters driving economic and environmental performance via a global sensitivity analysis. This aids in refining the multi-objective robust design optimization (MO-RDO) framework by pinpointing key design variables and objectives amid data uncertainties. Additionally, the formulated MO-RDO provides a mix of environmentally and economically optimal network designs and operational parameters and highlights the trade-offs between them. The designs and trade-offs are evaluated using financial metrics like net present value (NPV), return on investment, and discounted payback period. These metrics are calculated over the project life, considering the initial investment and net savings. For the considered case, the environmental design has a 10% higher investment cost compared to the economically optimal solution but reduces total emissions (TE) by 13% and improves operational cost savings, which is crucial for better financial indicators. The proposed framework aligns with the EU transition plan to incorporate waste energy sources and decarbonization paths, estimating only a 3% increase in NPV as a risk for the environmentally optimal solution on a financial scale.   • A generalized thermodynamic and economic framework to assess the potential business case of 5GDHC networks • A framework to quantify the impact of uncertain energy market and demands on network KPIs • Polynomial chaos expansion for uncertainty quantification on 5GDHC networks • A robust machine learning-based modeling approach to improve the computational efficiency • Multi-objective robust design optimization to find the optimal design under the influence of uncertainties [ABSTRACT FROM AUTHOR]

[Display omitted] • Green hydrogen integration via wind power for commercial greenhouse. • Transitioning cogeneration from natural gas to hydrogen for electricity generation. • Nine scenarios analyzed for hydrogen production, transportation, blending and usage. • Evaluated levelized cost of hydrogen, IRR, payback, and discounted payback. • 10% hydrogen blend reduces levelized cost; 100% blend improves IRR and payback. This study investigates the feasibility of using green hydrogen technology produced via Proton Exchange Membrane (PEM) electrolysis powered by a 200 MW wind farm for a commercial Greenhouse in Ontario, Canada. Nine different scenarios are analyzed, exploring various approaches to hydrogen (H 2) production, transportation, and utilization for electricity generation. The aim is to transition from using natural gas to using varying combinations of H 2 and natural gas that include 10 %, 20 %, and 100 % of H 2 with 90 %, 80 %, and 0 % of natural gas, to generate 13.3 MW from Combined Heat and Power (CHP) engines. The techno-economic parameters considered for the study are the levelized cost of hydrogen (LCOH), payback period (PBT), internal rate of return (IRR), and discounted payback period (DPB). The study found that a 10 % H 2 -Natural Gas blend using existing wired or transmission line (W-10H 2) with 5 days of storage capacity and 2,190 h of CHP operation per year had the lowest cost with a LCOH of USD 3.69/kg. However, 100 % of H 2 using existing wired or transmission line (W-100H 2) with the same storage and operation hours revealed better PBT, IRR, and DPB with values of 6.205 years, 15.16 % and 7.993 years respectively. It was found impractical to build a new pipeline or transport H 2 via tube trailer from wind farm site to greenhouse. A sensitivity analysis was also conducted to understand what factors affect the LCOH value the most. [ABSTRACT FROM AUTHOR]

Buildings have significantly contributed to high energy demand (30.3%) and GHG emissions (26.1%) worldwide. Consequently, many developed countries have set carbon-neutral targets for 2050, mandating that all new constructions thereafter be designed as net-zero emission buildings (NZEBs). To achieve this goal, one of the most practical sources of renewable energy, solar power, is employed in this study to estimate the economic feasibility of implementing NZEBs in the non-residential sector of the United States. While past studies have typically estimated the economic payback period of solar power technology by assuming fixed values for "PV energy conversion rates (%)" and "investment costs ($USD)", this paper carefully investigated the economic feasibility of "solar-based NZEBs" by precisely tracking these dynamic future changes in PV panels. These techno-economic variables were carefully predicted using a statistical technique known as the five-parameter logistic (5 PL) function. The results show that Site 4 is the only solar region suitable for implementing "PV-integrated NZEBs", reaching a payback period of 8.44 years in 2040 (Scenario 1). Furthermore, with small technological improvements in PV energy efficiency (%), buildings located in Site 3 and Site 4 can meet the net-zero emission target with payback periods of less than 10 years in 2034 (Scenario 2). Finally, starting in 2044, the "PV-integrated system" will have a payback period of approximately 7 years in most study locations, even without federal support for the solar investment tax credit (SITC). Accordingly, federal support for solar power generation will be more effective if the SITC rate is gradually reduced by 2.5% annually starting in 2033. In conclusion, this paper suggests the economic feasibility of implementing solar-based NZEBs in the United States non-residential sector by considering the synergetic effect of technological improvement and cost reduction in PV-integrated systems. • This study predicted the cost and efficiency of PV panels to estimate the economic feasibility of solar-based NZEBs. • The cost reduction and technical advancement in PV panels can remarkably improve the economics of solar power. • The 5 PL function is systematically modeled to predict the total investment cost and efficiency of PV panels. • In most study locations, solar-based NZEBs are projected to achieve a 7-year payback period beginning in 2044. • The federal support for the SITC rate (%) is recommended to be gradually lowered starting in 2033. [ABSTRACT FROM AUTHOR]

The commitment for energy-efficiency improvement becomes increasingly important in the context of global initiatives for sustainable development, and buildings have a great potential in this regard. As part of achieving energy-efficiency in residential buildings, the present study has analyzed the energy-saving potential and economic viability of adopting active energy efficiency measures (EEMs) on a detached family house in warm-humid climate of South India. The EEMs considered were selective air-conditioning (AC), lighting control, thermostat setting, mixed-mode ventilation, and energy-efficient AC, lighting and appliances. The modeling and simulations were performed by a reliable software (DesignBuilder, V.6) to estimate the annual energy consumption of the building with and without EEMs. The individual and combined contributions of EEMs in reducing the building's energy performance index (EPI) were quantified, and their economic viability was assessed in terms of discounted payback period (DPP). The results showed that about 63.5% reduction in EPI was possible by implementing the proposed EEMs, and the DPP for the additional investment was estimated to be 4.94 years. • Impact of active energy-efficiency measures (EEMs) on residential buildings. • Active EEMs show significant energy-saving potential. • All proposed EEMs are attractively cost-effective. • Collective adoption of active EEMs could reduce EPI by 63.45% [ABSTRACT FROM AUTHOR]

Romania has recently modified its legislation concerning energy production using photovoltaic systems to support the use of renewable resources. A program which offers subsidies for the procurement and installation of solar photovoltaic systems is in progress. This paper presents the economic assessment of residential solar photovoltaic systems connected to the grid in Romania under the new regulation. The valuations were conducted for six photovoltaic systems with different capacities that can be included in the legislation concerning prosumers; eighteen cities were chosen for a nationwide investigation and five types of household annual electricity demand. The capabilities and efficiency of the photovoltaic systems were simulated using PVSOL, while Net Present Value, Internal Rate of Return, Profitability Index and Discounted Payback Period were used to determine the feasibility of the systems. A sensitivity analysis was carried out to examine the effect of injected energy price on the system's efficiency. The results showed the systems were economically feasible when subsidies were available, especially those with a smaller energy production capacity. In Romania, the photovoltaic systems can be economically competitive in certain situations, like it is recommended to increase the subsidies, especially in the Northern part of the country to compensate for lower irradiance. • Economic analysis of 6 grid-connected residential rooftop PVs in Romania. • Assessment based on recently adopted regulation that supports PVs deployment. • NPV, IRR, PI and DPP calculation to determine PV systems economic feasibility. • Sensitivity analysis studied the effect of injected energy price on PVs viability. • 3.3 kW and 5.5 kW PV are profitable in all cities and annual consumptions studied. [ABSTRACT FROM AUTHOR]

This study presents an economic analysis of grid-connected residential rooftop PVs in Turkey under the current feed-in tariff (FiT) scheme. Three solar parts are formed on the solar map of Turkey to discuss the effect of solar radiation differences between regions on the feasibility of the systems. Nine provinces are selected for a nationwide analysis. 5 kW rooftop PVs are simulated using HOMER Grid. Discounted Payback Period (DPBP), Internal Rate of Return (IRR) and Profitability Index (PI) are used to ensure the viability of the systems from all aspects. DPBP below 8 years, IRR above 13.12%, and PI above 2 are considered feasible. The results showed that current DPBP, IRR, and PI of the systems are in the range of 7.75–14.43 years, 13.68%–6.87%, and 2.02–1.28, respectively. The systems are attractive only in one province in the southern part, and far from being investable in the northern part. A sensitivity analysis is performed to analyze the effect of varying FiT and PV initial cost on the feasibility of the systems and make policy implications. It is recommended to increase the amount of residential PV incentives in Turkey and develop a regional support mechanism, considering solar differences between regions. • Economic analysis of 5 kW grid-connected residential rooftop PV systems in Turkey. • DPBP, IRR, and PI are in the range of 7.75–14.43 years, 13.68%–6.87%, and 2.02–1.28. • Under current FiT, rooftop PVs in central and northern Turkey are infeasible. • Regional FiT rates should be determined considering regional solar differences. • The FiT rate should be updated periodically considering installed rooftop PV capacity targets. [ABSTRACT FROM AUTHOR]

Prediction of solar radiation data using different soft computing approaches like Multi layer Perceptron (MLP), Artificial Neuro Fuzzy Inference System (ANFIS), and Radial Basis Function (RBF) for East coast region of India has been presented in this paper. Based on the input data like sunshine duration, temperature and humidity for the period of 1984-1999, soft computing models for a solar radiation data are analysed. The performances of these models are evaluated by comparing the predicted and measured data in terms of absolute relative error. Results obtained by ANFIS model predicted better compared to the results obtained using RBF and MLP. Based on the predicted solar radiation data, the efficiency of a solar flat plate collector is carried out. It has been found out that the soft computing approach is very promising for predicting of solar radiation and for calculation of efficiency of a solar flat plate collector. Eastern India region is considered for the present analysis due to its peculiar characteristics of solar radiation and cyclonic nature in the coastal areas. [ABSTRACT FROM AUTHOR]

Due to the late introduction of Feed-in Tariff (FiT) Scheme to Hong Kong's context, its effectiveness, efficiency, and optimization have merely been investigated yet. Therefore, this study proposes two FiT mechanisms according to the policy characteristics and structure elucidated from existing literatures (i.e., payoff, tariff, and contract structures) (i) Mechanism 1 (i.e., M1): follows the current policy characteristics with a short-term contract structure, which terminates in 2033; and (ii) Mechanism 2 (i.e., M2) introduced a widely adopted policy characteristic with a long-term contract structure, which allows to sell all electricity generated to the power grid. The proposed FiT rate under M1 and M2 guarantees the profitability of the solar photovoltaic (PV) installers with different scales. For residential PV installers (i.e., small-scale PV systems with installed capacity less than10 kW), 6–10 years of discounted payback period (DPB) is considered as the optimization objective. As for industrial PV installers (i.e., large-scale PV systems with installed capacity of 200–1000 kW), 8–12% of internal rate of return (IRR) is considered as the optimization objective. Results indicate that the current FiT rate is slightly high for residential PV installers, and it is recommended to be lowered after 2024 to fit the proposed FiT range, and then levered up in 2028 to ensure the profitability of late participation under M1. Meanwhile, the current FiT rate is found significantly low for industrial PV installers, and it is suggested to be levered up to the proposed FiT range. Furthermore, policy reform is highly recommended altering from M1 to M2 when current policy expires (i.e., 2033). In terms of the techno-economic analysis based on the calculation of levelized profit of electricity (LPOE) where self-consumption of PV system-generated electricity is considered as energy bill savings under M1, the long-term profitability for industrial PV installers under M1 is found to be higher than M2, whereas the opposite is observed for residential PV installers. The contribution of this study is attributed to the flexibility and applicability of the optimized results, the context-specific investigation of the market-independent renewable energy development, and the comprehensive parameters considered in the model development. The results of this study are believed to shed light on policy implications, grid parity, and investment recommendations for the government, utility companies, and PV installers in the long run. [Display omitted] • Payoff, tariff, and contract structures regarding FiT Scheme are reviewed. • FiT rates were optimized under current (M1) and improved (M2) FiT mechanisms. • DPB and IRR are considered for residential and industrial PV installers. • Results have shed light on policy implications regarding current FiT rates. • Policy reform is suggested according to economic analysis in a long run. [ABSTRACT FROM AUTHOR]

Conceptually, hybrid photovoltaic/thermal (PV/T) system is superior to conventional side-by-side photovoltaic (PV) and solar thermal (ST) system due to the increase of energy output per unit collector coverage area. The current study aims to demonstrate the advantages of applying a liquid-based PV/T system over a side-by-side system in a real office scale building to support its electricity and hot water demand via computer program simulations of the explicit dynamic PV, ST and PV/T system models. Second, an economic analysis considering the time value of money is presented to evaluate the viability of installing a solar collector system with the adoption of PV/T instead of the side-by-side option. The discounted payback period, which has considered the maintenance and parts replacement costs, of the PV/T system design option is found to be encouraging. The sensitivity analysis shows that even under large variations of different factors in the calculation model, positive net present value is dominant in most cases within the analysis time period. The study reflects desirable potential of incorporating of PV/T technologies in real office buildings under subtropical climate region like Hong Kong. [ABSTRACT FROM AUTHOR]

Implementing appropriate passive design strategies at the early design stage of a building is a viable option for energy conservation in buildings. While literature is plenty on various passive solutions, a systematic approach for integrating all feasible options in a given building for a given location is lacking. As part of achieving energy-efficiency in residential buildings, the present study has analyzed the energy-saving potential and economic viability of adopting passive energy conservation measures (ECMs) on a detached family house in warm-humid climate of South India. Individual ECMs were assessed based on their energy-saving potential and cost-effectiveness, and the selected options were integrated in the building design. The modeling and simulations were performed by a reliable software (DesignBuilder, V.6) to estimate the annual energy consumption of the building with and without ECMs. The individual and combined contributions of ECMs in reducing the building's energy performance index (EPI) were quantified, and their economic viability was assessed in terms of discounted payback period (DPP). After finalizing all the viable passive design strategies, two options were proposed for the roof: cool roof painting and green roof. The results showed that about 34% reduction in EPI was possible by integrating the proposed ECMs with cool roof, while it was about 32% with green roof; the corresponding DPPs for the additional investment were estimated to be 4.3 years and 5.73 years. The present study provides a systematic approach for incorporating passive design options at the early design stage of air-conditioned residential buildings on the basis of energy performance and cost-effectiveness. This approach can be extended for different types of buildings in different climatic locations. • Impact of passive energy conservation measures (ECMs) on residential buildings. • Passive ECMs show significant energy-saving potential. • Most proposed ECMs are attractively cost-effective. • Collective adoption of passive ECMs could reduce EPI by nearly 34%. [ABSTRACT FROM AUTHOR]

The current work discusses the implementation of grid-connected, residential rooftop photovoltaic (PV) systems under the scenario of low (300 kWh/month), medium (600 kWh/month), and high (2100 kWh/month) electric loads. The analysis shows that, under all load scenarios, using rooftop PV systems with increasing PV ratings increased renewable fraction (by at least 5% for 1 kW PV under high electric load to as much as 89% for 12 kW PV under low electric load) and reduced carbon emission (by at least 5% for 1 kW PV under high electric load to negative carbon emission for 12 kW PV under low electric load). Furthermore, the highest PV rating (12 kW PV) was preferred under low, medium, and high electric loads, with net present cost (NPC) 29%, 72%, and 29% lowered than the respective grid reference systems. Nevertheless, a long discounted payback period was required, especially under low electric load (above 20 yr). A few scenarios with regard to PV module price, PV sellback rate, tariff rate, and carbon tax were therefore analyzed, which led to NPC reductions of 20%, 40%, 40%, and 12%, respectively, for 6 kW PV under low electric load, in addition to shortened discounted payback periods. Although Malaysian data were used for analysis purposes, the current work has worldwide implications, where it serves as a techno-economic model that provides a sustainable development framework for understanding technically and economically the installation of rooftop PV systems for residential households and driving the implementation of rooftop PV installations especially across Southeast Asia. • Grid-connected, residential rooftop PV systems with different loads were analyzed. • PV with higher ratings increased renewable fraction and reduced carbon emission. • The highest PV rating was preferred under low, medium, and high loads, NPC-wise. • Changes in PV module price, sellback rate, tariff rate, and carbon tax lowered NPCs. • The findings serve as a model that provides a sustainable development framework. [ABSTRACT FROM AUTHOR]

• NPV and DPBP of intensive and extensive green roof (GR) installation were estimated using 10,000 trials. • Different scenarios were considered for estimating the financial performance of GR installation. • The most influential variables in financial feasibility of GRs for private and social sectors were identified. • Monte Carlo simulation was used to consider every uncertainty in financial feasibility of GR installation. • Short- and long-term costs and benefits of GR installation were investigated, and their values were estimated. Green roofs (GRs) have several private, environmental, and social benefits, though financial issues have been considered a major barrier to its widespread use. The lack of knowledge and information regarding the value and applicability of each such benefit has resulted in limited adoption of GRs in Malaysia. Hence, the aim of this research is to analyse the financial feasibility of GR installation, considering social and private perspectives (where the applicability of benefits varies across various scenarios). To do that, the applicable short- and long-term costs and benefits of GRs were identified through reviewing the literature. Then, the variables' values were investigated and calculated using Monte Carlo simulation. GRs' net present value (NPV) and discounted payback period (DPBP) were analysed in different private scenarios to derive its financial feasibility out in Kuala Lumpur. Additionally, projected social benefits were analysed to indicate the government's financial benefit from GR adoption. The results showed that NPV for the private sector could be up to $1072.44 m2 and $735.11 m2, while it is most likely around $390.78 m2 and $258 m2 for intensive GR (IGR) and extensive GR (EGR), respectively. Most probably, the DPBP would be between one and nine years and one and six years for IGR and EGR, respectively. Additionally, considering the social benefits of GR, IGR has the potential to offer up to $314 m2; the amount is much lower for EGR at $55 m2. Moreover, it was found that energy saving is the most influential variable affecting NPV in private and social perspectives. Finally, it was concluded that GR installation could be financially feasible if all private benefits are applicable. Since GR has social financial benefits, the initial costs could be partially covered by the government as an incentive for GR installers. [ABSTRACT FROM AUTHOR]

• Detailed numerical model of high-temperature heat pumps up to 150 °C. • Performance of heat pump cycles with low global warming potential refrigerants. • Two-stage cycle with flash tank shows better performance than single-stage cycles. • Two-stage cycle is more cost effective for high temperature lifts. • Payback period for large heat pumps with a lift of 40 K can even be 3 to 4 years. This work investigates the techno-economic aspects of high-temperature heat pumps used for waste heat recovery. The heat pump produces heat at a temperature up to 150 °C from heat of below 100 °C based on both single- and two-stage cycles, with the aim of identifying the most cost-effective among various heat sink and heat source temperatures. Refrigerants with low-global warming potential are considered and a validated heat pump model is used to calculate the cycle performance. Then, the equipment cost of the different configurations is calculated as a function of the component parameters and system scale. This approach provides a trade-off between high efficiency versus high cost, in order to identify the most cost-effective configuration at each temperature level. The results show that the specific equipment cost of the heat pump is usually in the range of 150 to 300 EUR/kW, mostly depending on the cycle design and temperature. Moreover, the discounted payback period of industrial installations shows a large scatter, and can even be as short as 3 to 4 years. The overall outcome is that the single-stage cycle with an internal heat exchanger is favoured in terms of economic performance, except with large temperature lifts of over 50 K, in which a two-stage cycle shows superior cost-effectiveness. [ABSTRACT FROM AUTHOR]

The main purpose of this study is to evaluate the economic feasibility of the BIPV system as a building envelope material for the whole building skins. The paper is dealing with the lifecycle cost analysis (LCCA) of BIPV system in the capitals of all the European Union member states (EU) as well as the capitals of Norway and Switzerland. The results revealed that by a discount rate of zero, BIPV system could refund all the investment even on the north facades while in terms of traditional building envelope materials as an alternative option for building skins, there would be rarely added benefits after investment. Furthermore, the societal and environmental benefits of a BIPV system in Europe have its greatest impact on the south façade. Moreover, for all the studied directions of building skins with a discount rate of five present in Europe except the north facade, just the quantified amount of societal and environmental advantages of BIPV systems could almost reimburse all the invested money. The results illustrated that the BIPV system as a building envelope material for the whole building skins could reimburse not only all the investment costs but also become a source of income for the building. • BIPV is presented as a building envelope material for the whole building skins. • Economic analyses of a BIPV system in 30 countries are presented. • NPV, DPP, and IRR calculation for BIPV as a material for the whole building skins are done. • Replacing conventional façade materials with BIPV modules for building skins is feasible. [ABSTRACT FROM AUTHOR]