Energy Payback Period Research Articles

Thermo-economic-environmental analysis of a biomass-fueled natural convection dryer with thermal storage materials

Using biomass as a fuel in dryers decreases reliance on fossil fuels and encourages the adoption of renewable energy sources, contributing to the overall energy security of the region. In order to achieve this, a biomass-fueled natural convection dryer has been developed, and the effects of thermal storage materials like paraffin wax and pebbles are assessed to evaluate the thermo-economic-environmental analysis of the dryer for ginger drying. The research aims to examine the energy and exergy efficiency and to verify the environmental and economic feasibility of using these thermal storage materials in the dryer. The experiments are conducted under different circumstances, including cases without thermal storage materials, using only paraffin wax or pebbles, and simultaneously using both materials. The results indicate that combining thermal storage materials yields the highest heat energy retention, maintaining higher temperatures for longer durations, and demonstrating superior energy and exergy efficiency. The dryer is also found to have a positive environmental impact with an energy payback period of 1 year and the potential to mitigate 22.82–22.89 tonnes of CO2 over its lifetime. The financial assessment of the dryer shows that it has a payback period of 0.31–0.37 years and can produce 2218.38–2223.91 kg of dried ginger annually.Graphical

Comparative study on productivity of double slope solar still using different wick and energy storage materials

The aim of the proposed study is to evaluate the efficiency of Double Slope Solar Still (DSS) using different wick and energy storage materials. In the study, wick materials such as jute, cotton and sponge were used in combination with energy storage materials such as mild steel, cast iron and copper. The experiments were conducted using DSS with different combinations of wick and energy storage materials to determine the efficient performance combination. The results show that sponge and copper have higher efficiency with wicks and energy storage materials. The results show that the maximum amount of water produced in a single day was 3147 ml when the DSS system was used with a combination of sponge and copper materials. This range shows an increase of 17.47 % and 12.44 % over the DSS with jute and copper and the DSS with the combination of cotton and copper respectively. The DSS showed the highest average energy efficiency when used in conjunction with a combination of sponge and copper, namely 51 % of the average efficiency. This corresponds to an increase of 18.60 % and 10.86 % compared to the combination of DSS with jute and copper and the combination of DSS with cotton and copper respectively. The best evaporation heat transfer coefficient of 345 W/m2K was determined for the combination of DSS with sponge and copper. Average exergy efficiency is also maximum of 3.076 % for the DSS with sponge and copper materials, which is higher than other investigated combinations. The proposed system has an energy payback period of 1.26 years, an energy production factor of 0.78, a life cycle efficiency of 6.9 % and a cost of $0.031 per litre of water produced in the environmental economic analysis.

Optimizing the Integration of Building Materials, Energy Consumption, and Economic Factors in Rural Houses of Cold Regions: A Pathway

Limited material options and economic conditions significantly restrict the potential for energy efficiency improvements in rural houses in China’s cold regions. It is worth exploring how to propose suitable energy-saving renovation plans for rural houses in cold regions under practical constraints. By using Grasshopper within Rhinoceros 8 software, an algorithm integrates material selection, energy consumption calculations, and economic analysis. The method efficiently generates thermal optimization schemes, providing insights into energy use, costs, and payback periods. In a case study of a typical rural house in Daqing City, the optimized scheme achieved over 70% energy savings compared to traditional homes, with renovation costs amounting to less than 40% of residents’ annual income and a 2-year payback period. This significant improvement highlights the potential of the proposed method in enhancing the energy efficiency and economic viability of rural house renovations.

Enhance Power Generation of PV Array under Partial Shading Conditions by a Lo Shu and Optimal SuDoKu Puzzle Fusion Topology

A novel Lo Shu and Optimal SuDoKu Puzzle Fusion Topology (LS-OSDKP) is presented to disperse shading effects and enhance photovoltaic (PV) array output power under partial shading conditions (PSCs). Incorporating the ancient Chinese Lo Shu magic square puzzle and the Optimal SDKP topologies, the proposed LS-OSDKP is capable of alleviating current mismatch losses, decreasing wiring loss, simplifying the P-V curves of the array, and significantly improving shading dispersion. Under six PSCs, the performance of the proposed topology was evaluated using a 9 × 9 PV array and compared to the total-cross-tied (TCT), Twisted Two-Step, SDKP, Optimal SDKP, and Lo Shu topologies. Simulation results confirmed that the proposed method could extract the highest averaged power of the PV array among the six topologies, with a 10.47% power improvement when compared to the TCT. Additionally, the LS-OSDKP is capable of effectively reducing the wiring length by 29.09% compared to the Lo Shu. Moreover, the proposed method has the highest potential for energy savings and revenue generation. Compared to the conventional TCT configuration, it could improve extracted energy by approximately 9.58% and shorten payback time by approximately 9.06%. Consequently, the advantages of the proposed LS-OSDKP topology include an increase in extracted power, a reduction in wiring loss, and a shorter energy payback period.

Comparative energy metrics and annual efficiency analyses of CPC‐ETC integrated single slope solar desalting unit

AbstractThis paper deals with the investigation of N identical compound parabolic concentrator evacuated tubular collector included single slope solar desalting unit (N‐CPC‐ETC‐SSU) by incorporating energy metrics for solving contemporary issue of water scarcity in the society. It will contribute to the sustainable development of society and recede the dependency on fossil fuels, too. The energy metrics investigation is important for energy system because it talks about the feasibility of the system. The methodology consists of getting fundamental equations from energy balance equations. All fundamental equations with relevant data are fed to the code developed in MATLAB followed by the computation of overall energy and exergy. All types of climatic situations have been considered for the analysis. Data required for the same are accessed from IMD, Pune, India. The energy payback period, energy production factor, and life cycle conversion efficiency for N‐CPC‐ETC‐SSU have been calculated at eight number of collectors, 0.012 mass flow rate and 0.14 m water depth. Results of N‐CPC‐ETC‐SSU have been compared with results of SSU included with ETCs. Concludingly, energy payback period is lower by 6.41%, energy production factor is higher by 6.25% and exergy‐based life cycle conversion efficiency is higher by 96.39% for N‐CPC‐ETC‐SSU than N‐ETC‐SSU.

Performance Evaluation and Cost Analysis of Photovoltaic Thermal (PVT) System Using the Triangular Shape of Absorber with Different Water-based Nanofluids as Coolants

The worldwide energy demand is continuously increasing, prompting experts to recommend using alternative energy sources to conserve natural gas, fossil fuels, and electricity. Photovoltaic thermal (PVT) systems emerge as a viable solution, generating electrical and heat energy simultaneously while freeing carbon dioxide (CO2) emissions. These systems offer sustainable green technology for supplying renewable electricity and heat to commercial and domestic applications. This study delves into the performance of a photovoltaic thermal (PVT) system featuring an isosceles triangular-shaped absorber design. It considers size variations of 0.02 and 0.03 m while maintaining a constant aspect ratio. Water-based nanofluids such as CuO/w, MgO/w, and ZnO/w, with a nanoparticle volume portion of 4%, alongside pure water as a coolant, are utilized with a variation of mass flow rate ranges from 0.028 kg/s to 0.11 kg/s, allowing for an exploration of its impact on performance parameters. A numerical model is established to comprehensively analyze the system's performance, applying an energy balance equation to its components. An economic analysis is also conducted to assess the system's cost-effectiveness and determine the energy payback time. Results indicate that the highest overall daily performance is achieved with ZnO/w nanofluid at a mass flow rate of 0.112 kg/s and a fluid flow channel size of 0.02 m. Comparatively, compared to other nanofluids and pure water, the average electrical, thermal, and overall performances achieved are 14.57%, 22.36%, and 36.40%, respectively. The energy payback periods are 5.5, 5.2, 5.4, and 4.8 years for CuO/w, MgO/w, ZnO/w, and Pure water, respectively. Furthermore, it is observed that a higher mass flow rate correlates with higher system performance parameters.

Integrated Approach for Enhancement of Vapor Compression Refrigeration Systems with Spiral Condenser Retrofitting and Refrigerant Blend Compatibility

An integrated approach for enhancing Vapor Compression Refrigeration Systems (VCRS) through Spiral Condenser retrofitting and compatibility with refrigerant blends is proposed in this paper. The objectives include the design and development of an experimental setup compatible with refrigerant blends, experimentation and analysis of results for retrofitting the setup with a Spiral Condenser, validation of experimental results, and determination of system energy effectiveness and payback period. The methodology involves systematic design, experimentation, validation, and analysis, culminating in insights into VCRS enhancement strategies. The findings contribute to advancing VCRS technology, optimizing performance, and promoting sustainability in refrigeration systems.

Investigation of the effects of synthetic wind speed parameters and wind speed distribution on system size and cost in hybrid renewable energy system design

The accuracy of wind speed data has an important impact on determining power output from a Hybrid Renewable Energy System including wind turbine. For a better estimation of energy price or payback period, it is crucial to determine both monthly average wind speed values and distribution parameters. Studies evaluating the sensitivity of wind speed distribution parameters concerning the optimal system size are lacking in the literature. This work fills the gap in the literature and for the first time, the effects of wind speed distribution parameters and wind speed distribution on the optimum system are statistically demonstrated. According to this case study, if these parameters are not set correctly, the Cost of Energy may be faulty between −14.024% and +37.804% for the Photovoltaic-Wind-Battery-Inverter system, may be faulty between −19.024% and +97.05% for the Wind-Battery-Inverter system and may be faulty between −56.437% and +65.250% for the Wind-Inverter system. When the default distribution parameters of the HOMER software are used, the errors are −0.609%, −18.30%, −34.215% respectively. This study reveals that in addition to monthly average wind speed values, distribution parameters should be chosen as accurately as possible. The innovative aspect of this work is the statistical presentation of how synthetic wind speed distribution can affect Hybrid Renewable Energy System sizing and at the same time Cost of Energy. Its importance is that it provides more precise results by guiding optimization studies using synthetic meteorological data, which is a popular field of study.

Comprehensive optimization of shading and electrical performance of roof-mounted photovoltaic system of Venlo-type greenhouse in the severe cold region

Agrivoltales is a new paradigm that combines agricultural and renewable energy production, which can reduce the energy consumption in severe cold region. Install PV panels on the greenhouse rooftops can provide required power for the greenhouse, but the shading from the PV panels may affect crop development and yield. In this article, the roof-mounted PV system's performances of a novel Venlo-type PV greenhouse in the severe cold region of China were evaluated and analyzed. By controlling the angle between the south-and-north-facing roof and the horizon (α and β) from 10° to 70°, each 10° increase was chosen as a design case, forming 49 cases in total. The shading rate, daily light integral (DLI) and the performance of the PV system were considered to optimize the Venlo-type PV greenhouse. The results show that when α is not less than 40° and β is 10°, the shading rate of Venlo-type greenhouse is less than 25 % and photosynthetically active radiation (PAR) higher than 23.5 mol/m2·d which meets the requirements of most greenhouse crops growth. Through comprehensive evaluation, the optimal case is α at 40° and β at 10°, of which the specific production is 1404 kWh/kWp/year which is the most, both investment and energy payback period are the shortest, power generation is 114.9 MWh/yr, carbon emission reduction is 11202 kg/yr the shading rate is below 25% throughout the year. The case with α at 70° and β at 70° has the largest power generation and carbon emission reduction. However, its shading rate, PAR, specific production, and payback period have the worst performance. The results can facilitate the development of the optimization of PV greenhouses and contribute to the carbon neutrality of facility agriculture and the life of local farmers.

Life cycle environmental analysis of offshore wind power: A case study of the large-scale offshore wind farm in China

China's decarbonization is indispensable for the large-scale utilization of renewable energy. In this process, the development of offshore wind energy has become an important support, because in the eastern region of China, especially the coastal areas, there's the most load requirements but limited onshore renewable resources. Under the goals of both carbon neutral and sustainable development, however, there's still a research gap in evaluating the environmental impacts of large-scale offshore wind plants in China. In this study, the research performed a comprehensive process-based life cycle environmental analysis of a large-scale (400 MW) offshore wind farm with large wind turbine units (5 MW) in China. Global Warming Potential is 25.73 g CO2-eq/kWh and greenhouse gas payback time is calculated as 12.05 months. Fossil fuel consumption amounts to 0.31 MJ/kWh with an energy payback period of 25.56 months. Material resources and ecotoxicity to freshwater need more attention with the values of 1.68 CTUe/kWh and 3.32 10−6 kg Sb-eq/kWh, respectively. The manufacturing stage contributes most to all the impacts examined. The disposal and recycling process shows significant environmental benefits for most impacts but exerts burdens on the particulate matter. Focusing on Global Warming Potential, the wind turbine generation set has the highest effect, among which the blades contribute 73.2% of it. Further, the evolution of electricity and heating mix of China and use of biomass-based precursors could decrease 57% of the blades' greenhouse gas emissions in 2050. This study could provide guidance on the sustainable design and policy-making of offshore wind farms.

Development and Economical Analysis of Innovative Parabolic Trough Collector Integrated Solar Still

Experimental setup of the integrated parabolic trough collector (PTC) with solar still was developed. PTC was designed considering the solar geometry and the physical laws of parabolic shape and the concentrators. Test were conducted at the location with latitude 19.9975ON and longitude 73.7898OE. Theoretical analysis was done using ray tracing and engineering equation solver (EES) software while designing the system. PTC system was developed with dimensions of 1.5 m length, 1 m width and a concentration ratio (CR) of 21.22. Theoretical thermal efficiency was predicted as 48.1% whereas experimental average thermal efficiency is observed as 42.76%. The observed temperature difference between the vapor and the glass cover is about 17 °C and between ambient air and vapor is about 24.4 °C. Maximum water temperature in the conventional solar still was 64.6 °C where as for the PTC coupled solar still was 74.4 °C. PTC coupled solar still is having averagely 37% higher production rate. This has definitely added an advantage because of the higher energy absorption rate compared with the conventional solar still. PTC coupled solar still system has nearly 35% more heat absorption. Total embodied energy of the system is around 896.875 kWh. Total capital cost of the system is Rs. 41300/-. Total annual output of pure water is around 3 L/Day. Estimated energy payback period is around 2.29 years and the total carbon credit earned is Rs. 2165.38 per year.

A Roof Refurbishment Strategy to Improve the Sustainability of Building Stock: A Case Study

The aging of the building stock in most cities highlights the relevance of refurbishment to achieve sustainability. Current refurbishment practices are often short-sighted and do not encompass holistic strategies beyond energy saving. This research study aims to analyze the factors involved in roof refurbishment versus current decision-making determinants. The objective is to identify the barriers that hinder their implementation and to find arguments to support roof renovations. A multicriteria analysis, which considered environmental, economic and performance factors, was employed to select optimal roof refurbishment solutions. This study evaluated five solutions. With interviews held with construction professionals and a survey of experts and homeowners, the preferences and criteria for making decisions about roof refurbishments were analyzed. Simulation tools were then used to estimate the energy savings, payback periods and environmental impact for a representative building in the study area. The results were extrapolated to a neighborhood level. The results highlight the importance of considering factors, such as weight, cost and user preferences when selecting suitable refurbishment solutions. The findings not only estimate the potential energy savings and carbon emission reductions in the area but also underscore the relevance of roof refurbishments for prolonging a building’s life span to contribute to sustainability.

Impact of variation in input parameters on energy matrices of dual slope active solar desalting unit

AbstractThis article presents the relationship between energy matrices of a dual slope solar desalting unit integrated with a number (N) of photovoltaic thermal flat plate collectors (NPVTFPC‐DSU) and the effect of variation in mass flow rate and N for a sustainable solar distillation. Although extensive research has been done on dual slope active solar desalting unit, however, the area of the impact of variation in and N on energy matrices of NPVTFPC‐DSU remains still untouched. This study is an attempt to bridge the gap that has been highlighted. An exhaustive analysis is performed considering all types of climatic situations of New Delhi, India. MATLAB is used to calculate the overall energy, exergy, and energy matrices for NPVTFPC‐DSU based on fundamental equations and relevant data as inputs. Concludingly, it is evident that there is a decrease in the value of energy payback period and life cycle conversion efficiency as the value of increases at a given value of N for ≤ 0.10 kg s−1. For kg s−1, the values remain constant. For NPVTFPC‐DSU, 6 and 10 are the best and most favorable values of N as far as energy‐based energy matrices and exergy‐based energy matrices are concerned.

Phase separation and domain crystallinity control enable open‐air‐printable highly efficient and sustainable organic photovoltaics

AbstractOrganic solar cells (OSCs) have emerged as a promising solution for sustainable energy production, offering advantages such as a low carbon footprint, short energy payback period, and compatibility with eco‐solvents. However, the use of hazardous solvents continues to dominate the best‐performing OSCs, mainly because of the challenges of controlling phase separation and domain crystallinity in eco‐solvents. In this study, we combined the solvent vapor treatment of CS2 and thermal annealing to precisely control the phase separation and domain crystallinity in PM6:M‐Cl and PM6:O‐Cl systems processed with the eco‐solvent o‐xylene. This method resulted in a maximum power conversion efficiency (PCE) of 18.4%, which is among the highest values reported for sustainable binary OSCs. Furthermore, the fabrication techniques were transferred from spin coating in a nitrogen environment to blade printing in ambient air, retaining a PCE of 16.0%, showing its potential for high‐throughput and scalable production. In addition, a comparative analysis of OSCs processed with hazardous and green solvents was conducted to reveal the differences in phase aggregation. This work not only underscores the significance of sustainability in OSCs but also lays the groundwork for unlocking the full potential of open‐air‐printable sustainable OSCs for commercialization.

Relative comparison of the benefits of wall envelope insulation materials in the South African energy zones, subject to the new national building energy efficiency standards

Introduction: South Africa is ranked among the 20 highest greenhouse gas (GHG) emitters worldwide, mainly due to its heavy reliance on coal for energy. The residential building industry can play a significant role towards the minimization of both GHG emissions and energy consumption. This research assesses the beneficial impacts of utilizing wall envelope insulation measures using five insulation materials, for a detached residential building, within the seven energy zones of South Africa in accordance with the South African National code for Building energy efficiency (SANS10400-XA).Methods: Lifecycle analysis (for 50 years), regression methods and sequential search techniques of building energy modelling were used to determine both the energy saving implications of adopting the insulation materials (at various levels of thickness), and their corresponding energy payback periods. The study area consisted of eight selected locations representing all the seven energy zones in South Africa (Welkom, Witbank, Thohoyandou, Cape Town, Pretoria, Ixopo, Sutherland, and Fraserburg).Results: Sutherland (zone 6), Cape Town (zone 4) and Fraserburg (zone 7) benefitted most from energy savings due to application of insulation measures. Witbank (Zone 2), Thohoyandou (zone 3) and Pretoria (zone 5) never benefitted from application of wall envelope insulation (in terms of energy savings). Cellulose and straw yielded the lowest payback periods. Generally, polyurethane yielded the highest net energy savings at lower insulation thickness levels, while cellulose was preferable at higher insulation thickness levels in Welkom (zone1) Cape Town (zone 4), Ixopo (zone 5H), Sutherland (zone 6) and Fraserburg (zone 7).Discussion: Lower optimal wall envelope insulation thicknesses (that maximized energy savings) appeared to correspond to locations with higher annual temperature ranges. Higher temperature ranges (hence, higher degree days) would ensure that more energy is saved in order to keep the indoor temperatures within the acceptable comfort limits, due to application of insulation. However, the selection of insulation material is also influenced by other factors such as resistance to insect and mould attack (which easily affect bio-insulation materials), fire retardancy, durability (which affects cellulose), sound proofing, structural strength, and resistance to water vapour.

Relative Comparison of Benefits of Floor Slab Insulation Methods, Using Polyiso and Extruded Polystyrene Materials in South Africa, Subject to the New National Building Energy Efficiency Standards

This article aims to assess the benefits of floor slab insulation measures using extruded polystyrene (XPS) and polyisocyanurate (also referred to as polyiso or PIR) insulation materials at various levels of insulation thicknesses for a detached residential building. An EnergyPlus simulation analysis was carried out within the seven energy zones (represented by eight locations) of South Africa in accordance with the South African national code for building energy efficiency (SANS10400-XA). The energy savings and payback periods related to the use of the insulation over a lifecycle period of 50 years were assessed. Cape Town (zone 4) behaved differently from other locations and hardly benefited from the application of floor slab insulation measures. Generally, polyiso (PIR) insulation performed better than XPS for vertical gap insulation, and lower insulation thicknesses required higher insulation depths to maximize energy savings. Similarly, lower insulation thicknesses (25 mm and 50 mm) required higher perimeter insulation widths to maximize energy savings for horizontal perimeter insulation, especially in Sutherland (zone 6) and Cape Town. The maximization of energy savings was also achieved at low insulation thickness for the full floor slab insulation method, except for Sutherland and Fraserburg (zone 7). The locations that benefitted most from the floor slab insulation methods were Pretoria (zone 5), Thohoyandou (zone 3), Sutherland (zone 6), Fraserburg (zone 7), Welkom (zone 1), Ixopo (zone 5H), Witbank (zone 2), and Cape Town (zone 4), in that order. Generally, higher net energy savings are achieved in areas with lower humidity levels and areas with greater annual sums of both cooling and heating degree days.

Roofing systems and energy efficiency in low-rise buildings: A comparative study across India’s diverse climates

The building envelope is the interface between the external atmospheric conditions and the indoor environment. It contributes to approximately 60%–70% of the heating and cooling load. The building envelope constitutes walls, fenestrations, and roofs from which thermal transfer from the roof is significantly very high compared to walls in low-rise buildings.This research paper aims to provide recommendations for energy-efficient roof design considering roof form, material, and external coating suitable for various climate conditions of India. The paper’s methodology consists of a literature review of related research papers, learnings from the roofing system of energy-efficient building case studies, and all possible energy-efficient roofing systems that would be simulated for energy efficiency and thermal comfort in five climate types of India. The expected outcome of this paper would be in the form of recommendations for roofing systems in different climate type and their potential for energy saving from the highest to the lowest. This research would be done in three stages viz, Step-1: Literature Review and case study of best practices: A review of the related literature and best practices examples would be done to formulate the maximum possible cases for the simulation. Step-2: The roofing systems, including building form, material (Thermal and insulation), and finishes (reflectance), would be simulated one by one for various climate types of India (composite, hot & dry, warm and humid, moderate and cold) to optimize energy efficiency and payback period. Step-3: Special roof types like Green roofs, cool roofs, Photovoltaic roofs, roof ponds, and the like are simulated and compared for their effectiveness in selected climate types. Based on the literature review, simulation results, and analysis, the recommendations are framed for energy-efficient roofing systems in the selected climate type with respect to heat transfer through the roof and thermal comfort.

Evaluation of an improved indirect solar dryer for Curcuma Amada without and with stone chips as thermal energy storage: An investigation on kinetics, energy, exergy, quality and economic aspects

The drying kinetics, energy, exergy, quality, and economic studies of a solar dryer with and without energy storage have been conducted. The original configuration of a solar air collector (SAC) has been modified by adding waste stone chips beneath the absorber plate. Data related to mass loss, solar radiation, and temperatures were gathered during the experiments in both the configurations. Curcuma Amada samples had initial moisture of 87.4 % and achieved an equilibrium moisture level of 4.4 % within 8 h in the dryer equipped with waste beverage canned absorber plate and storage (SDCWS) and for dryer without storage (SDCWOS) it took 26 h. Out of the eleven drying models tested, the Midilli and Kucuk model exhibited the most favorable fit for Curcuma Amada in both the experiments. The average efficiencies for the collector and dryer were 67.26 % and 21.88 %, respectively, in SDCWOS. In contrast, the efficiencies for the collector and dryer were 87.95 % and 29.63 %, respectively, in the SDCWS. Exergy parameters such as in, out, loss, efficiency, improvement potential, waste exergy ratio, and sustainability index were estimated for both the configurations. Quality analysis was further carried out for both SDCWOS and SDCWS in terms of total polyphenol content, total flavonoid content and color. The estimated energy payback periods were 1.7 years for SDCWOS and 0.47 year for SDCWS, considering a 20-year lifespan. In all assessed aspects, the SDCWS configuration showed more favorable outcomes. The results of this study have the potential to positively impact the sustainable advancement of agricultural drying techniques within rural areas.

Towards energy efficiency: retrofitting existing office buildings using smart technologies

Buildings are considered one of the main causes of increasing CO2 emissions due to their excessive consumption of energy. The drive towards sustainability represents a challenge especially in existing buildings. The aim of the research is to support the built environment’s move onto a low-carbon path using smart technologies. This research highlights the role of smart building technologies in increasing energy savings of office buildings in Egypt, taking into consideration their incremental cost. Based upon data available on Excellence in Design for Greater Efficiencies (EDGE) website, association rule has been applied using Apriori Algorithm to identify the most used smart technologies in EDGE-certified office buildings, in addition to the different smart-orientated retrofitting scenarios that could be applied. Using EDGE software, energy assessment of an existing office building in Egypt was performed. This assessment acts as a “reference point” to quantify the impact of each smart technology and retrofitting scenario on the energy savings, incremental costs, and payback period. Limitations of the application of the different smart technologies impacted the selection process for the different scenarios. These limitations can be summarized in the suitability of application in the existing building’s systems, the availability and cost in the local market, and the potential of the building’s infrastructure adaptation to the proposed technologies. Based upon the above limitations, the best scenario was selected. Results showed that smart technologies have a great role in retrofitting of office buildings reaching more than 20% energy savings. In addition, the high initial cost of applying smart technologies could be covered within around 3 years of operation. This research could be used as a guide for improving energy performance of existing office buildings in Egypt using smart technologies.

A comprehensive analysis of small-scale building integrated photovoltaic system for residential buildings: Techno-economic benefits and greenhouse gas mitigation potential

The present paper aims to highlight the techno-economic and greenhouse mitigation potential of the small-scale building integrated photovoltaic (BIPV) of 10 kW suitable for residential as well as small commercial agglomerations. To carry out this investigation a mathematical model has been developed utilizing the RetScreen simulation tool. The model has been implemented by choosing various cities across India that are major residential hubs such as Delhi, Lucknow, Indore, Jodhpur, Pune, and Coimbatore. The result showed that the energy production remained highest at Jodhpur i.e. 15678 kWh amounting to Rs. 94107/year of energy savings. The energy payback period (ENPP) for a 10 kW system has been obtained between 6 and 7 years. The highest capacity utilization factor (CUF) was obtained during March but the performance ratio (PR) and efficiency remained highest during December–January (Winter). Jodhpur had the highest net present value (NPV) and profitability index (PI) which indicated that Jodhpur was the most lucrative site among all locations. The simple and the equity payback (SPP and EPP) obtained were between 7.1 and 9.3 years. The Levelized cost of electricity (LCOE) was between Rs. 5.81/kWh- Rs. 6.95/kWh. The result also revealed that the 10 kW BIPV system was capable of reducing 15 tonnes/year of carbon and more than 400 tonnes of carbon in 25 years. The carbon credit earned by a single installation was more than Rs. 70 thousand in a year. If the current model is applied to 3000 households in a locality, there can be 40–50 GWh of energy savings amounting to Rs. 230–280 million.