Search Results (37)

Decarbonising the existing residential sector is a central priority of European energy policy, yet masonry buildings from the early 2000s remain significantly underrepresented in net-zero energy building (NZEB) research. This study addresses this critical gap by evaluating a holistic deep retrofit of a representative single-family house in Cracow, Poland, providing a scalable model for the Central European housing stock. The methodology integrated structural and systemic interventions: eliminating thermal bridges via balcony removal, enhancing the envelope with 0.25 m of mineral wool (λ = 0.036 W/m K), and installing innovative active triple-glazed windows (U_w = 0.85 W/m² K) with integrated electric heating foils. The energy system was transformed by replacing a coal-fired boiler with an 8 kW air-to-water heat pump and a 7 kWp photovoltaic array, complemented by a green roof on the western pitch for passive thermal buffering. Verified results demonstrate a radical reduction in the non-renewable primary energy (EP) index from 224.56 kWh/(m²·a) to 0.00 kWh/(m²·a), achieving full compliance with stringent “WT 2021” standards. Economic analysis reveals that the integrated approach is financially viable, with a simple payback time (SPBT) of 7.1 years when supported by available subsidies. This study concludes that the integration of active glazing, high-performance insulation, and nature-based solutions offers a replicable and economically sound roadmap for transforming legacy housing into zero-emission assets. Full article

The high expansion rate of industrial-scale photovoltaic (PV) systems in emerging economies requires proper performance prediction models that consider particular climatic variabilities. Although the theoretical potential of solar energy in South Asia is well documented, there still exists a gap in the validation of simulation models to operational data over long periods in subtropical monsoon climates. Unlike prior studies, this work combines multi-year operational data with dynamic TRNSYS simulations to quantify both technical and environmental performance of a 1 MW PV system under subtropical monsoon conditions. This paper provides a detailed performance evaluation of a 1 MW grid-connected PV system located in Punjab, Pakistan. The actual performance of the system is compared with a dynamic simulation model that is created in the Transient System Simulation Tool (TRNSYS) using three years of operational data. Four different scenarios are analyzed: (1) Ideal Theoretical Operation, (2) Actual Field Data, (3) Simulated Operation with Maximum Power Point Tracking (MPPT), and (4) Simulated Operation without MPPT. The results reveal that the real system produced an average of 1342 MWh/year, whereas the MPPT-enabled simulation predicted 1664 MWh/year, indicating a performance difference of 19.3%. Statistical validation revealed a strong correlation ($R^2=0.84$) between the model and reality, yet identified a normalized Root Mean Square Error (nRMSE) of 26.8%. This deviation represents a performance gap which is deconvoluted into agricultural soiling losses and grid curtailment. The research work quantifies the technical effect of MPPT where a 27% operational advantage is realized in comparison to fixed-voltage cases, proving its necessity in climates with high diffuse radiation during monsoon seasons. Economic analysis demonstrates a Levelized Cost of Energy (LCOE) of $0.0378/kWh of the existing system, and a Simple Payback Time (SPBT) of 4.74 years at the current industrial tariffs. Sensitivity analysis also indicates that in case of an increase in grid tariffs to 50 PKR/kWh, Internal Rate of Return (IRR) increases to 18.8%. Environmental analysis confirms a carbon emission reduction of 765 tons/year. These results validate the techno-economic feasibility of large-scale PV in the area and provide an important understanding of the critical yield losses in monsoon seasons, which offers an effective robust benchmark for future industrial energy policy in developing economies. Full article

High regeneration energy demand remains a critical barrier to the large-scale deployment of ethanolamine-based (MEA-based) CO₂ capture. This study adopts an Al₂O₃ ceramic-membrane heat exchanger (CMHE) to recover both sensible and latent heat from the stripped gas. Experiments confirm that heat and mass transfer within the CMHE follow a coupled mechanism in which capillary condensation governs trans-membrane water transport, while heat conduction through the ceramic membrane dominates heat transfer, which accounts for more than 80%. Guided by this mechanism, systematic structural optimization was conducted. Alumina was identified as the optimal heat exchanger material due to its combined porosity, thermal conductivity, and corrosion resistance. Among the tested pore sizes, CMHE-4 produces the strongest capillary-condensation enhancement, yielding a heat recovery flux (q value) of up to 38.8 MJ/(m² h), which is 4.3% and 304% higher than those of the stainless steel heat exchanger and plastic heat exchanger, respectively. In addition, Length-dependent analyses reveal an inherent trade-off: shorter modules achieved higher q (e.g., 14–42% greater for 200-mm vs. 300-mm CMHE-4), whereas longer modules provide greater total recovered heat (Q). Scale-up experiments demonstrated pronounced non-linear performance amplification, with a 4 times area increase boosting q by only 1.26 times under constant pressure. The techno-economic assessment indicates a simple payback period of ~2.5 months and a significant reduction in net capture cost. Overall, this work establishes key design parameters, validates the governing transport mechanism, and provides a practical, economically grounded framework for implementing high-efficiency CMHEs in MEA-based CO₂ capture. Full article

This case study evaluates the economic and energy efficiency of retrofitting a hospital heating system in Krakow, Poland, by transitioning from a district-heating-only model to a bivalent hybrid system. The analyzed configuration integrates air-to-water heat pumps (HP), a 180 kWp photovoltaic (PV) installation, and a 120 kWh battery energy storage (ES) unit, while retaining the municipal district heating network as a peak load and backup source. Utilizing high-resolution quasi-steady-state simulations in Ebsilon Professional (10 min time step) and projected 2025 market data, the study compares three modernization scenarios differing in heat pump capacity (20, 40, and 60 kW). The assessment focuses on key performance indicators, including Net Present Value (NPV), Levelized Cost of Heating (LCOH), and Simple Payback Time (SPBT). The results identify the bivalent system with 40 kW thermal capacity (Variant 2) as the economic optimum, delivering the highest NPV (EUR 121,021), the lowest LCOH (0.0908 EUR/kWh), and a payback period of 11.94 years. Furthermore, the study quantitatively demonstrates the law of diminishing returns in the oversized scenario (60 kW), confirming that optimal sizing is critical for maximizing the efficiency of bivalent systems in public healthcare facilities. This work provides a detailed methodology and data that can form a basis for making investment decisions in similar public utility buildings in Central and Eastern Europe. Full article

The growing global demand for sustainable energy solutions has spurred interest in hybrid renewable energy systems, particularly those combining photovoltaic (PV) solar and wind power. This study records the technical and financial feasibility of establishing hybrid solar photovoltaic and wind power stations in Iraq, Al-Rutbah and Al-Nasiriya, with a total power of 60 MW for each, focusing on optimizing energy output and cost-efficiency. The analysis evaluates key technical factors, such as resource availability, system design, and integration challenges, alongside financial considerations, including capital costs, operational expenses, and return on investment (ROI). Using the RETScreen program, the research explores potential locations and configurations for maximizing energy production and minimizing costs, and the evaluation is performed through the calculation Internal Rate of Return (IRR) on equity (%), the Simple Payback (year), the Net Present Value (NPV), and the Annual Life Cycle Savings (ALCSs). The results show that both PV and wind technologies demonstrate significant energy export potential, with PV plants exporting slightly more electricity than their wind counterparts. Al Nasiriya Wind had the highest output, indicating favorable wind conditions or better system performance at that site. The results show that the analysis of the proposed hybrid system has a standardizing effect on emissions, reducing variability and environmental impact regardless of location. The results demonstrate that solar PV is significantly more financially favorable in terms of capital recovery time at both sites, and that financial incentives, especially grants, are essential to improve project attractiveness, particularly for wind power. The analysis underscores the superior financial viability of solar PV projects in both regions. It highlights the critical role of financial support, particularly capital grants, in turning renewable energy investments into economically attractive opportunities. Full article

Energy and economic assessments are of great relevance in the context of decision processes for the most optimal solutions for building renovations. Following the method recommended by UNIDO, economic analyses of thermal modernization options are carried out based on the Simple Payback Time (SPBT), Net Present Value Ratio (NPVR) and Internal Rate of Return (IRR) indices. Incorporating these indicators and a new approach that involves aggregating thermomodernization activities not only in the cold and warm seasons separately, but throughout the whole year, an economic evaluation of the thermomodernization of a production space was carried out. In this case study, the renovation options included wall insulation, window replacement, the installation of infrared heater, a two-flow air diffuser (TFAD) and variable air volume. The economic effect indicated by the highest NPVR over a normative period of 15 years was obtained for the installation of an infrared heater and a TFAD with a variable mode ventilation system. The SPBT for this case was also the lowest. Full article

This paper presents the techno-economic feasibility of using grid-connected PV hybrid systems to supply power in large grid-dependent academic institutions. The study was conducted using the administration building of Moi University in Kenya. The power consumption profile of the building was collected using a PCE-360 power analyzer. The peak load demand was found to be 60 kW. Using random variability constants of 4% for day-to-day and 4% time-step load variability, a peak demand of 70.58 kW was obtained, which was used in our simulation. The solar radiation and temperature data for this site were collected from the weather station of the university. The hybrid system was simulated using HOMER Pro software. It was found from the simulation results that the optimal system was the solar PV/grid without battery storage, which had a levelized cost of energy (LCOE) of KSH 8.78/kWh (USD 0.072), net present cost (NPC) of KSH 27,974,492 (USD 230,813), capital expenditure (CAPEX) of KSH 26,300,000 (USD 216,997), and a simple payback period (SPBP) of 5.08 years for a 25-year life span. This system, when compared to the existing grid, showed an 83.94% reduction in the annual electricity bill of the administration building. These results demonstrate a reduction in energy cost by a renewable energy fraction of 67.1%. Full article

Greenhouse gas emissions depend on natural and anthropic phenomena; however, to reduce emissions, we can only intervene in terms of anthropic causes. Human activity is very different in various countries and cities. This is mainly due to differences in the type of urban environment, climatic conditions, socioeconomic context, government stability, and other aspects. Urban building energy modeling (UBEM), with a GIS-based approach, allows the evaluation of all the specific characteristics of buildings, population, and urban context that can describe energy use and its spatial distribution within a city. In this paper, a UBEM is developed using the characteristics and consumption of eight typical buildings (archetypes) in the climate zone of Santiago de Chile. The archetype-based UBEM is then applied to the commune of Renca, a critical suburb of Santiago, with the use of QGIS to analyze the energy demand for space heating and the potential for energy saving after four retrofitting interventions. Knowing the costs of the retrofitting interventions and the energy price, the simple payback time was evaluated with the reduction in GHG emissions. Starting from the actual building stock, the results show that the most effective retrofitting intervention for the commune of Renca is the thermal insulation of walls and roofs; due to the type of dwellings, this particular intervention could be more convenient if associated with the installation of solar technologies. This methodology can be replicated with the data used by urban planners and public administrations available for many Chilean cities and in other countries. Full article

In this research, a modified organic Rankine cycle (ORC) system has been presented and examined. This system incorporates a gas turbine as an additional subsystem to boost the enthalpy of geothermal brine. The primary objective of this study is to perform an economic evaluation of the modified ORC system, wherein a gas turbine is utilized to enhance the quality of geothermal steam. The suggested modified ORC system is particularly well-suited for areas abundant in geothermal resources with low to medium temperatures. It offers a more effective utilization of such resources, resulting in improved efficiency. The study considered 10 different working fluids and 8 types of gas turbines used to heat the geothermal water brine witch, the temperature vary of which varies between 80–130 °C. Various flue gas temperatures behind the heat exchanger, as well as temperatures of the return of the geothermal water to the injection hole, were examined. Based on that, 990 variations of configuration have been analyzed. The research showed that the lowest simple payback time (SPBT) values were achieved for the SGT-800 gas turbine and the working fluid R1336mzz(Z), for example, for an electricity price equal 200 USD/MWh and a natural gas price equal to 0.4 USD/hg, resulting in a SPBT value of 1.45 years. Additionally, for this variant, the dependence of SPBT on the price of electricity and the depth of the geothermal well was calculated; assuming the depth of the geothermal well is 2000 m, SPBT changes depending on the adopted gas prices and so for 150 USD/MWh it is 2.2 years, while at the price of 100 USD/MWh it is 5.5 years. It can be concluded that a decrease in SPBT is observed with an increase in the price of electricity and a decrease in the depth of the geothermal well. The findings of this study can help us to better understand the need to utilize low and medium temperature geothermal heat by using combined cycles (including gas turbines), also from an economic point of view. Full article

A micro gas turbine (MGT) is an advanced technology with a simple structure and fast load response. It represents a good choice for the next generation of distributed power systems, where fossil fuels are going to be largely replaced by biofuels and renewable sources. In this context, this work aims to investigate and compare the performance of gradually more complex energy systems integrating a micro gas turbine plant: simple cogenerating asset, integrating a solar field, presence of a gasifier, and the addition of a bottoming ORC. In all cases, a thermo-economic analysis has been carried out for an application in the agricultural sector. Agricultural waste can be used to create a syngas as fuel for MGT through a gasifier, promoting the utilization of carbon-neutral alternative fuels to reduce harmful emissions. The authors considered the electrical and thermal needs of a hypothetical agri-food company to build the electrical and thermal load curves. The new and more complex cogeneration plant, designed by using the Thermoflex 30 software, leads to an increase in electrical power, recovered thermal power, overall electrical efficiency, carbon neutrality, and cogeneration indexes. In particular, the presence of the solar field promotes a reduction in fuel consumption as well as greater heat input to the thermal unit. The addition of a bottoming ORC system increases the electrical power by 36.4%, without significantly penalizing the thermal unit. Moreover, thanks to the gasifier that offsets the fuel reduction costs, through an economic analysis of the entire plant, a payback time of the investment of less than 4 years is obtained. Full article

Supermarkets in Port Harcourt (PH) city, Nigeria, predominantly rely on diesel electricity generation due to grid instability, leading to high electricity prices. Although solar photovoltaic (PV) systems have been proposed as an alternative, these supermarkets have yet to adopt them, mainly due to high investment costs and a lack of awareness of the long-term financial and environmental benefits. This paper examines the technical and economic practicality of a PV system for these supermarkets using the PVsyst software and a spreadsheet model. Solar resources showed that PH has a daily average solar radiation and temperature of 4.21 kWh/m²/day and 25.73 °C, respectively. Market Square, the supermarket with the highest peak power demand of 59.8 kW and a 561 kWh/day load profile, was chosen as a case study. A proposed PV system with a power capacity of 232 kW, battery storage capacity of 34,021 Ah, a charge controller size of 100 A/560 V, and an inverter with a power rating of 60 V/75 kW has been designed to meet the load demand. The economic analysis showed a $266,936 life cycle cost, $0.14 per kWh levelized cost of electricity (LCOE), a 4-year simple payback time, and a 20.5% internal rate of return (IRR). The PV system is feasible due to its positive net present value (NPV) of $165,322 and carbon savings of 582 tCO₂/year. Full article

The pressing necessity to address climate change calls for the reduction in carbon emissions in the energy sector. Renewable energy communities (RECs) provide environmental, financial, and societal advantages that facilitate the shift towards sustainable energy sources. This paper examines the development of RECs in Italy through a case study in the Municipality of Assisi, and investigates the pivotal role played by public administrations as catalysts in the formation of RECs. Despite facing unique challenges and constraints, Assisi leverages RECs and the proactive approach of the local government to overcome barriers hindering the implementation of renewable energy projects. A municipality-led REC of a total power of 2 MWp by 2030, using clusters of prosumers and consumers and including energy-intensive municipal facilities, is investigated. Through rigorous simulations and the resulting shared energy, the study conducts a comprehensive analysis encompassing technical, energy, and economic aspects. The results, including relevant energy indices, are presented and various scenarios are discussed as the energy shared varies. Finally, sensitivity analyses show that the profitability strongly depends on the cost of energy, the remuneration from the sale, and the value of the incentive earned on the shared energy: the simple payback time ranges from 8 to 14 years and NPV varies from EUR 0.8 to 4.5 M. Full article

Considering water resources, Poland ranks among the last in Europe. By using rainwater for sanitary purposes, drinking water is saved. This article presents the results of the economic analysis of rainwater utilization systems, based on a novel view that takes into account factors related to the location of the family detached house in the country, such as average annual rainfall and water and electricity prices. Two cases of rainwater management systems (domestic-garden and garden) were analyzed in six locations, while considering the diversity of precipitation in Poland in two variants, depending on the material of the tank, with two options of traditional electrical installation or photovoltaic panels. The evaluation of the profitability of the investment was carried out on the basis of indicators: NPV, LCC, and SPBT. The results of the analyses of all variants give the conclusion that, to achieve the greatest financial benefits, it is crucial that the building’s rainwater demand is fully met by rainfall, the unit price of water is significantly higher than the unit price of electricity, operating costs are as low as possible through the use of renewable energy sources, and subsidies are a significant percentage of the investment. Full article

The Renovation Wave for Europe highlighted the role of the public building stock for which Directive 2012/27/EU has set an annual renewal rate of 3%, which should rise to reach the goal of decarbonization by 2050. In this paper, the energy retrofit of an educational building—at the academic level—in Southern Italy was investigated. The aim was to evaluate the incentive share, which could accelerate the energy efficiency process, to achieve a cost-effective nZEB. The results show that the highest incentive rate is required for interventions on the opaque building envelope, which are also those that allow the least energy savings. An incentive rate of about 45% for the energy efficiency of the transparent envelope is necessary to reduce the payback time by about 7 years. The efficiency of the plants and the installation of a PV system are energetically and economically convenient even without forms of economic incentive. Finally, if the building is brought to high energy standards—a primary energy saving of 46% and energy class A3—an incentive rate of 40% is required to repay the intervention in about 10 years. Full article

Excessive urban construction is primarily driven by uncontrolled population growth, which has serious consequences for the environment, energy, cost, and human life in general when building materials are massively used. In terms of energy and economic efficiency, buildings that make use of sustainable construction materials and technologies perform better. This is because building in an eco-friendly way results in less waste. Agro-industrial by-products and insulating materials are two examples of sustainable materials that have been put to good use in the climate change mitigation effort and to preserve the environment. Precast components are emphasized as a viable option that is suitable for this purpose and may potentially fulfill the need for housing units. Thus, this study investigated the viability of employing agricultural waste consisting of pomegranate peel waste to produce fired clay bricks. Results demonstrated that the optimum amount of pomegranate peel waste was determined to be 15%, and the optimal firing temperature was determined to be 900 °C. The thermal conductivity of all test samples was lower than that of conventional brick. Furthermore, when compared to conventional wall brick, all the tested samples of manufactured brick reduced energy consumption by 17.55% to 33.13% and carbon dioxide emissions by 7.50% to 24.50%. In addition, the economic feasibility of employing each synthetic sample was evaluated by computing the simple payback time (SPP). It was determined that 1.88–10.74 years were required for the brick samples to provide a return on their initial investment. Due to its ability to decrease heat gain, preserve energy, minimize CO₂ emissions, and shorten the payback time, burned clay bricks manufactured from pomegranate peel waste are regarded as a feasible building material. Hence, manufactured bricks are usually considered an exceptional contribution to environmental sustainability. Full article