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[Display omitted] Two significant manifestations of the passive effect of building photovoltaic (PV) systems include the enhancement of the thermal performance of the envelope and the reduction of building energy consumption through the installation of PV systems on the building envelope's surface. This paper presents a review of the passive impact of PV roof systems, PV wall systems, and PV window systems, as well as the effects of the external environment, building ontology conditions, and PV system configuration on the passive effects. The study concludes that in regions with a hot climate, the shading effect of PV roof and PV wall systems during the summer can reduce the building's cooling load by 20% to 70%. In frigid climate regions, heating energy consumption during the winter can be reduced by 10% to 20% through the PV wall system's ability to recycle hot air in the cavity. Indoor thermal comfort can be improved while reducing lighting energy consumption by 3% to 14% with PV windows. A comprehensive analysis of the existing literature on the influencing factors reveals that the influencing factors of the passive effect have complex uncertainties and non-linear coupling characteristics under various conditions. To provide a theoretical foundation for the scientific popularization of photovoltaic systems, this paper identifies current research problems and prospective research directions for building photovoltaic systems based on the current status of research in the literature. [ABSTRACT FROM AUTHOR]

This paper presents dynamic air-based models of a hybrid photovoltaic-thermal (PVT) collector. The models are developed with the aim of estimating the temperature of the collector components and therefore of estimating the annual generation of electrical energy and thermal energy outputs, by using actual climate data of six different cities based on Köppen-Geiger-Photovoltaic (KGPV) climate zones. The results show that the unglazed type collector has the best PV cooling while the dual channel collector has the best air heating among air-based PVT collectors. The results also indicate that the use of additional fluid enhances both electrical and thermal performance. The dynamic models are validated by comparison with results found in the literature. The paper also discusses a novel bi-fluid PVT system combined with a storage tank and an H-infinity based robust controller that can handle uncertainties. The results of the bi-fluid system show that the fraction of energy demand covered by the system is highly dependent on climate conditions and the collector's surface area. It was found that for a small-scale house (standard for four people), the proposed system can cover more than 70% annual domestic hot water demand for cities with high solar irradiance and 32% for a city with low solar irradiance. • Estimating annual generation of electrical and thermal energy outputs of PVTs for various climate zones. • A new design of a bi-fluid PVT system which incorporates a storage tank as well as a robust controller. • Consistency of the dynamic models has been validated by comparison to results found in literature. [ABSTRACT FROM AUTHOR]

• Novel FADSS is fabricated for the water production from thin air. • It incorporates a small blower to facilitate airflow through the system. • Condenser is used for the condensation of desorbed vapour from silica gel. • Bed design study is performed for effective solar energy utilization. • Honeycomb bed, with an airflow rate of 30 LPM, is found as optimal. This paper presents an innovative approach addressing the problem of clean and drinking water scarcity by developing and optimizing a flow-assisted desiccant solar still (FADSS) that harnesses atmospheric moisture using solar energy. It is an extension of the conventional desiccant solar still incorporating a small blower to facilitate airflow through the system, and operates in a two-cycle process. During the night (adsorption process), ambient air is blown continuously through the bed, enabling the silica bed to adsorb moisture. During the daytime (desorption process), solar energy heats the silica bed, releasing the adsorbed water vapour to the circulating air, which carries it to the condenser. The water vapour condenses in the condenser, and the air returns to the bed. The paper focuses on optimizing the FADSS by studying the airflow rate, a critical parameter for maximum water production. It varies from 20 to 60 L per minute (LPM). Further, the paper also investigates the four different bed design configurations for maximum water production. The FADSS thermal efficiency is calculated to analyze its performance. The highest water production of 694 ml/day was achieved using a 0.25 m2 glazing area in the honeycomb bed design. This output was obtained by employing an airflow rate of 30 LPM and a 3 cm thickness of silica gel. Interestingly, The honeycomb bed effectively utilized ∼38 % of solar energy for water production in the FADSS, while about 9 % was lost due to sensible cooling of the air in the condenser. The findings suggest that the honeycomb bed, with an airflow rate of 30 LPM, represents the optimal operational parameters for this system. [ABSTRACT FROM AUTHOR]

• Assessing solar power technical potential in China with high-resolution data. • Quantifying the gap between actual generation and technical potential at plant level. • Actual solar power generation is only 30% of the technical potential. • Technology, construction, and management factors cause the underperformance. Improving the power output of solar photovoltaic (PV) farms is critical to maximize the potential of PV power and reduce extensive land use in the context of large-scale deployment of renewable energy. In this paper we developed an integrated solar power potential assessment framework to quantify the gap between technical potential and actual generation of solar PV farms on national, provincial, and plant scales, and identify the key factors that cause the underperformance of PV farms. Specifically, to assess technical potential, hourly meteorological reanalysis data is adopted and the power generation-related parameters are calculated (i.e. optimal panel tilt, array spacing, packing factor etc.) with consideration of their spatial variability. For actual power generation, a detailed plant-level dataset is first established by this study which integrates technical, operational, and geospatial information from 145 solar farms across seven provinces in China. Our results show that the actual PV power generation per square meter is only 1/3 of the estimated technical potential. Technological factor is the primary factor, accounting for 48.43% of the underperformance, followed by engineering and management factors, accounting for 38.55% and 13.02%, respectively. The novelty of our study is revealing the underperformance level of solar farms in reality, identifying the causing factors, and highlighting the importance of integrating land-use efficiency indicators into solar power planning and development. [ABSTRACT FROM AUTHOR]

[Display omitted] • Conducting optimization in the MED desalination plants. • Transforming the process into a solar-powered one. • Making determination of cost-effectiveness by utilizing sensitivity analysis. • Parametric optimization of the multiple effect distillation process utilizing fossil fuels. • Identifying the most suitable solar collector and HTF from economic standpoint. The utilization of multi-effect distillation (MED) in thermal desalination processes is more widespread owing to lower energy consumption. The focus of this paper is to optimize the performance of MED through process optimization. It aims to identify the optimal operating conditions that result in maximum water and power production. Additionally, it investigates the potential of using solar renewable energy as a substitute for the current fossil energy source. Subsequently, a switch to solar energy was made with a focus on an economically viable approach. The research explored the best-suited collector and fluid for heat transfer among the 8 types of molten salt for use in the collector. Subsequently, an economic and sensitivity analysis was conducted using this procedure. The outcomes indicated that by enhancing the stated procedure, it was found that 27.93 Megawatt (MW) of heat would be required when 6938 ton/h of natural gas are burned. Additionally, the 4-effect MED process produced 6.123 MW of electricity and 116.5 cubic meters per hour (m3/h) of freshwater. The gain output ratio (GOR) of the process saw an uptick from 2.75 to 3.328, whereas MED efficiency showed progress from 13.76 to 49.218 %. The parabolic trough collector (PTC) collector outperforms the linear Fresnel collector (LFC) and solar dish (SD) collector in terms of efficiency among other results. To store heat for the rest of the day and night and supply thermal energy for the entire process, 155,542 square meters (m2) of this collector are necessary. Additionally, in regards to the thermal fluid of the PTC collector, coastal chemical registered heat transfer salt (HITEC salt), a commercial mixture of solar salt, has exhibited superior performance over other molten salts (for a total expenditure of 50 million dollars over two decades). In addition, the economic analysis has indicated a return rate of 32.46 % for the investment and a capital recovery period of 3.08 years for the process. The implementation of the mentioned process in renewable mode results in the avoidance of 18.5 tons per hour (ton/h) of carbon dioxide (CO2) emissions. [ABSTRACT FROM AUTHOR]

• The paper discusses challenges in integrating solar power in Norway, limited to 36% of feasible capacity. • Seasonal variations in solar energy production emphasize the need for year-round energy management. • A critical threshold of 36% feasible solar power integration highlights the importance of balancing production and consumption. • Effective energy management is crucial for aligning solar production with consumption patterns. This research study delves into the solar energy potential and capacity in Norway, aiming to assess the viability of solar power integration in the country's urban landscape. Through a comprehensive analysis, historical data, and PVsyst simulations, the study reveals that solar photovoltaic (PV) systems offer significant promise in contributing to Norway's renewable energy goals. The study uncovers a seasonal variation in solar energy production, with peak generation during the summer months due to extended daylight hours and more intense sunlight. However, winter months experience lower solar energy production due to limited daylight hours and weaker solar radiation. To fully exploit solar energy potential, effective energy management strategies such as energy storage, smart grid technologies, and demand response mechanisms are crucial. Moreover, the research highlights the relationship between energy consumption and solar energy production, emphasizing the importance of efficient energy management and capacity planning. Bridging the gap between supply and demand requires optimized solar energy utilization aligned with consumption patterns. A key finding of this study is the identification of a pivotal threshold: up to 36% of the feasible solar power, equivalent to 31 GWp, can be integrated into the grid to match daily production and consumption. However, exceeding this threshold leads to challenges in peak production times, necessitating exports or additional strategies to accommodate the excess energy. In conclusion, this study underscores the promising prospects of solar energy integration in Norway. By leveraging solar power's potential, implementing effective energy management measures, and addressing challenges, Norway can work towards a more sustainable and resilient energy future, reducing reliance on fossil fuels and making significant strides in combating climate change. [ABSTRACT FROM AUTHOR]

• The energy and cost benefits of dynamic PV-integrated shading devices are assessed. • Both energy efficiency and on-site energy generation benefits are considered. • Optimal design and operation of PV-integrated shading systems are determined. • PV-integrated overhangs can allow office spaces to achieve net zero energy operation. • For Australian office buildings, PV-integrated shading systems are highly cost-effective. The paper summarizes a comprehensive analysis to determine the energy and cost benefits of static and dynamic photovoltaic (PV)-integrated shading devices when applied to windows of office spaces located in different climate zones across Australia. The evaluated dynamic shading systems consist of rotating overhangs placed above the windows and operated to minimize the annual energy demands of office spaces. For the first time, the study determines through optimization-based controls the best angle settings for the rotating overhangs on hourly, daily, or monthly basis to minimize the energy consumption of office spaces in Australia. The analysis results indicate that both optimally designed static and optimally operated dynamic PV-integrated overhangs have substantial potential to reduce the annual energy needs of office spaces for all Australian climates with annual energy savings ranging from 45% to over 100% depending on the building orientation, window size, glazing type, and overhang depth. This high energy benefits are attributed to the multi-function capability of the PV-integrated shading systems to minimize cooling and space thermal loads while maximizing on-site electricity generation. Unlike the case of static shading devices, it is found that dynamic PV-integrated overhangs allow office spaces to reach net-zero energy operation for certain climate zones in Australia. [ABSTRACT FROM AUTHOR]

• Study feasibility of a Grid-Connected PV power supply system in data center's cooling system. • With storage batteries, utilization of PV power increased by up to 27.64 % in the discussed days. • Optimized number of battery groups and PV panels were given to reduce carbon emission. • Find threshold of battery's unit price for the adoption of it to maximize economy performance. • Provide guidance for design and operation of such system with q IT between 500 and 1100 W/m2. The cooling system of a data center accounts for a significant part of its energy consumption, and the adoption of solar energy can reduce its power demand from the grid. This paper investigated the optimal configuration of a grid-connected PV power supply system to a data center's centralized water-cooling system. Firstly, mathematical models for photovoltaic panels and storage batteries were established. Then, two operating strategies were proposed, respectively, for two systems with and without storage batteries, and the supply–demand matching performances were studied. With storage batteries, mismatch problem between electricity generated by photovoltaic panels and electricity consumed by the water-cooling system can be significantly improved. Utilization ratio of electricity generated by photovoltaic panels was increased by up to 27.64 % in the discussed typical days. Annual utilization of electricity generated by photovoltaic panels can also be significantly increased, especially when heat dissipation density is small. Lastly, the optimal configurations were discussed. To reduce carbon emission, number of battery groups were recommended for different heat dissipation density and number of photovoltaic panels. Full life-cycle carbon reduction ranged from 1.77 to 3.71 tCO 2 /m2 and carbon emissions reduced from 14.23 to 62.14 % as compared with the traditional system. As for the economic performance, the recommended number of photovoltaic panels are 798, 1330 and 1589 for heat dissipation density being 500, 800 and 1100 W/m2, respectively. While the recommended number of batteries was 0 if unit price of batteries is higher than 11.1 ten thousand yuan/group. [ABSTRACT FROM AUTHOR]

• The potential of rooftop solar photovoltaic (PV) in the context of the political, economic, social, technical and environmental (PESTLE) framework in Africa. • The prospect of dual use of building integrated photovoltaic (BIPV) in Africa. • Implementing appropriate energy policy and financing schemes in African cities. • Promoting a sustainable path for cost effective recycling and reuse of end-of-life PV in African cities. Power outage is a regular occurrence in most African cities due to increasing energy demand from population growth and commercial activities outstripping the grid capacity. This results in disruption to normal life putting stress on businesses and affecting development across the continent. This review paper investigates the potential of solar photovoltaic (PV) in African cities from three perspectives. Firstly, the potential of rooftop PV in the context of the political, economic, social, technical, legal and environmental aspects (PESTLE) is evaluated. Thereafter, sustainable waste management of solar PV panels is reviewed in anticipation for the upcoming wave of end-of life solar panels. Finally, the prospect of dual use building integrated photovoltaic (BIPV) as power generators and building components is investigated from case studies in Africa. Most studies highlight the strong potential of rooftop PV and BIPV due to the availability of high radiance in the continent. However, our review shows that affordability and lack of investment acts as a significant barrier to mass adoption of this technology which could be remedied by implementing appropriate energy policy and financing schemes. Alternative financing of PV products and service solutions such as leasing, pay monthly, pay-as-you-go, and subscriptions are emerging as popular options, and these approaches seem to act as drivers to market expansion. The review also emphasizes on the need for effective and sustainable waste management of solar PV products through implementing appropriately designed recycling schemes. This will need to be adopted now to ensure success and to prevent a waste management crisis in the future for the African continent. [ABSTRACT FROM AUTHOR]

• Proposal of a method to construct typical generic block models using local datasets. • Urban form influences strategy of solar technology in low-carbon scenario. • Solar cooling contributes to carbon reduction in subtropical areas. • Technology and morphology design can overcome the high-density constraints. The use of solar energy in an urban context is essential for low-carbon urban development and global climate change mitigation. In this paper, the application of multiple solar energy techniques, namely, photovoltaic (PV), photothermal (PT), and photothermal-driven cooling (PC) techniques, in tropical Macau was investigated. Based on the typological method, sixty generic block typologies were formulated. A parametric workflow was constructed to facilitate block modelling and simulate energy consumption and solar radiation. The optimal technique strategy for each typology was identified under a low-carbon scenario. The energy and environmental performance levels of the blocks were evaluated by calculating and comparing the solar potentials, load matching conditions, primary energy consumption levels, and carbon dioxide emissions. The results indicated that the PT technique should be preferred for blocks with high floor area ratio (FAR) values, while the PV technique should be prioritized for blocks with low FAR values under the low-carbon scenario. Moreover, the PC technique is necessary in subtropical areas to reduce carbon emissions. In addition, it is suggested that solar energy should be adopted in blocks with high site coverage ratio (SC) and low surface area-to-volume ratio (SAV) values, as well as blocks with low FAR values. Regarding blocks constrained by high-density urban development, appropriate decisions on technology and morphological design could help to overcome constraints and realize low-carbon community targets. This study could provide suggestions for urban planners and building designers in the application of the urban solar potential at the early stages of urban design or urban regeneration. [ABSTRACT FROM AUTHOR]

• The vertical temperature gradient were analyzed in offices. • An evaluation index for air-conditioning energy consumption was proposed. • The energy-efficiency advice on air-conditioning for offices is given. Installing curtains on windows prevents direct sunlight from entering the indoor working space. It also alters the direction of solar heat radiation and the spatial distribution characteristics of indoor heat gain. This paper analyzes the relationship between the change of heat gain in the working and non-working spaces of the room under the effect of curtains. Meanwhile, it proposes an index of The Useless Cooling Capacity Ratio (UCCR) of the room to analyze its useless cooling capacity. In the hot summer and cold winter region, this study employs experimental and simulation methods to investigate the influence of solar radiation intensity, curtain thermal characteristics, and other factors on the vertical temperature gradient and heat flux indoor during the summer. The results showed that installing curtains on the windows reduced the vertical temperature gradient of the working space and improved the thermal comfort. The vertical temperature gradients in the working and non-working zones under the experimental conditions were 0.24 °C/m and 0.66 °C/m for the room with curtains and 0.62 °C/m and 0.57 °C/m for the room without curtains, respectively. Curtains can regulate the spatial distribution of heat loads and UCCR in a room and make the room more energy efficient. The UCCR for rooms with and without curtains were 24 % and 18 %, respectively, with curtains adding 120 kJ of useless cooling capacity to the work area. [ABSTRACT FROM AUTHOR]

• Long-term operational monitoring of a Zero Emission Building (ZEB) in Beijing. • An existing building being retrofitted into a Zero Emission Building (ZEB). • Key Building Mounted Photovoltaic (BMPV) technologies are practically utilized and their effects are estimated. • The ZEB realized its own net-zero carbon emission and net energy production. • The ZEB could be a comprehensive experimental platform. Building mounted photovoltaic (BMPV) technology is a promised way to achieve carbon peak in building sector. Focused on the influence of heat from PV modules on building envelope's heat transfer and energy saving performance, and the power generation, the coupling mechanism of power generation and heat transfer of integrated photovoltaic technology on building façades has been investigated. The synergy of solar energy generation and building energy consumption have been studied in this paper. The installation method of building PV system was proposed, with which can achieve the maximum energy saving. Furthermore, the achievements have been applied in Zero Emission Building (ZEB) of China Academy of Building Research (CABR), demonstrating way to realize zero carbon building by integration of photovoltaic technology. Total of 236.1 kWp PV systems were installed in ZEB. Monitoring data shows that the annual power generation of ZEB could reach 212,382 kWh, and the power generation per building area is 73.79 kWh/m2, which could meet all the energy demands. In addition, it can supply extra power to surrounding buildings. The ZEB can provide experience and practice data supporting carbon peak in building sector. [ABSTRACT FROM AUTHOR]

• This paper presents an experiment on solar-powered air conditioning. • The study compares two scenarios: on-grid and off-grid, offering insights into their respective performances. • Evaluation metrics include solar fraction, energy consumption, and operational time fraction. • The solar-powered air conditioning system exhibits superior performance under higher demand and elevated temperatures. • The economic viability of the system is attractive, enhancing its appeal and potential for widespread adoption. Air conditioning is vital in maintaining indoor comfort and improving air quality, particularly in regions with high temperatures and humidity. However, the increasing demand for air conditioning has significant implications for energy consumption and the environment. Solar air conditioning can play a vital role in mitigating such impacts. This study presents an experimental setup that utilizes a solar photovoltaic system to power an air conditioning unit. The system is installed in a 36 m2-research lab at The University of Jordan, equipped with PV panels with a capacity of 2.67 kWp, a battery pack, a charge controller, an inverter charger, and an air conditioning unit. Two testing scenarios are conducted: an on-grid system connected to the electrical grid and an off-grid system operating independently. A clear sky day and a partially cloudy day were selected for each scenario in testing. The results were evaluated based on the solar fraction, energy consumption, and operational time fraction (OTF). The solar fraction was found to be higher during periods of higher demand and ambient temperature, and the average OTF was 70 % for all trials. In off-grid trials, the system had maintained operation solely on PV power during the studied load profile in the clear sky day. In contrast, limitations in charging power caused system shutdown in the partially cloudy trial. An economic analysis for the local payback period (PBP) was conducted based on the Hourly Analysis Program and PVsyst software simulation, which shows an attractive simple local PBP for on-grid and off-grid systems of 6.91 and 6.4 years, respectively. [ABSTRACT FROM AUTHOR]

The European Union has been allocating funds for the energy transition to meet escalating global energy demands while minimising the environmental impact. This paper focuses on the impact of post-pandemic policies on photovoltaic technology in Italy and Portugal, specifically analysing self-consumption schemes and energy communities. A techno-economic assessment identified optimal PV systems for four families in each country, considering financial incentives. Italy offers Superbonus 110 and Ecobonus schemes, while Portugal provides access to the Environmental Fund. Profitable PV systems with storage are feasible in Italy but not in Portugal. Superbonus 110 favours smaller systems, Ecobonus supports larger ones, and Portuguese policies prioritise smaller systems. Simulations of energy communities for the same families showed that in Italy, the best configurations consist of families acting as producers with larger PV capacities and smaller batteries. In contrast, in Portugal, the policies favour smaller PV systems without batteries, resulting in optimal configurations where families are solely consumers. This research underscores diverse national approaches to post-pandemic energy policies and their nuanced impacts on PV technology in Italy and Portugal. It can be concluded that energy communities offer greater profitability than individual self-consumption schemes. This is because individual households continue to prioritise self-consumption and personal savings while selling their excess energy at a more favourable price than what they would receive from the grid. • In Italy, there are financial incentives and in Portugal, electricity cost reductions. • The models used the Net Present Value and the Internal Rate of Return as indicators. • In Italy, Superbonus 100 favours smaller systems, while Ecobonus supports larger ones. • Smaller systems without batteries for self-consumption are more profitable in Portugal. • Energy communities are more economically viable in both countries. [ABSTRACT FROM AUTHOR]

• Actual operational data from nine commercial-scale solar PV systems in Virginia over single- to multi-year periods are used. • Facilities analyzed encompass four different end-use categories with summer- and daytime-peaking (SDP) electricity demand. • Granular performance analyses demonstrate a consistent potential to reduce peak demand for individual SDP customers and coincident peak demand for regional grids. • Properly sized systems (large enough but not oversized) can maximize financial savings for commercial solar customers. • With proper scale and policy support, solar PV can provide financial savings to solar customers, utilities, and utility ratepayers alike. The conventional approach to developing commercial behind-the-meter solar discounts peak demand savings and focuses on maximizing the number of installed panels with little consideration for optimizing economic benefits to solar customers, much less for utility ratepayers. While a select number of studies similarly point to the peak demand reduction benefits of distributed solar, they typically rely on simulations and theoretical models to support their conclusions. In contrast, this study draws on a wealth of empirical data from a commercial solar development company, demonstrating consistent peak demand savings for various solar customers as well as grid-scale benefits to utilities and their ratepayers. Using 5- to 30-minute interval data from solar arrays and utility meters, we analyze the impact of solar PV on operational energy demand for nine commercial facilities in Virginia, USA. All facilities analyzed exhibited a mid-day- and summer-peaking demand profile, making them ideal for solar integration. Through analyzing both sets of interval data, we find that solar reduced monthly peak demand by an average of 22.9%, consistently shifted peak load towards off-peak hours, and reduced demand during coincident peak periods for utilities in PJM, the mid-Atlantic regional transmission organization, by an average of 42.3%. In addition to demonstrating substantial peak demand reduction, these findings emphasize the importance of systematically optimizing system capacity according to facility-level energy consumption and utility rate tariffs. This paper debunks conventional dogma that distributed solar burdens non-participants with cross-subsidization, rather highlighting the need for policies which promote distributed solar access and more equitable energy grids. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to review findings on the integration of solar thermal collectors, photovoltaic thermal collectors, and heat pumps to provide both electrical and thermal energy. The energy consumption of HP systems in buildings is significant. Studies have verified the benefits of using PVT collectors in heat pumps to provide electricity and solar assistance to their cold sources. This article provides an overview of advances and progress in solar assisted heat pumps (HPs). Increasingly, heat pumps are integrated with thermal and photovoltaic solar collectors. Providing both heat and hot water as well as electricity, this integration can be applied to a variety of applications. The services range from providing power and heating to industrial and agricultural needs. The aim of this review is to examine research conducted over the past twenty years with an emphasis on studies that have significant implications for the evolution of the technology in the near future. In demanding environmental conditions, the coupling of Photovoltaic/Thermal collectors (PVT) with HP systems has demonstrated a noticeable improvement in system performance and operational reliability. By addressing critical challenges and unresolved issues, the subsequent discussions and recommendations serve to channel attention. This will lead to enhanced performance improvements in HP systems by directing efforts in this way. [ABSTRACT FROM AUTHOR]

• Apply a new optimization algorithm to retrofit the existing buildings envelope. • Use a solar panel system for energy efficiency. • Consider the net present worth and payback period. • Investigate the maintenance and facility operation degradation. To enhance the energy effectiveness of old buildings, retrofitting strategies are an efficient technique. The objective here is to apply a multiple-criteria optimization method to retrofit the building envelope. In this respect, a new metaheuristic algorithm, called Marine Predators Optimization Algorithm (MPOA) is used in this paper. The components that are investigated to be retrofitted are including roofs, windows, and outer walls. A photovoltaic system is considered to be employed on the rooftop. The degradation duration of the solar panels is studied. Also, for renewable energy development and its long-lasting impact on the retrofitting scheme, a maintenance design is considered. The optimum utilization of the financial investment for the maximization of energy savings and economic-related advantages are the main targets. Specifically, the major operation indicators of the retrofitting scheme are energy savings, payback period, and net present worth. A weighted sum technique is applied to solve the non-linear problem. The efficiency of the suggested model is a result of the designed retrofitting plan. [ABSTRACT FROM AUTHOR]