Rooftop Area Research Articles

Techno-Environmental Analysis of Facade Integrated Photovoltaics and Electric Vehicle Charging for University Building

Electric vehicles (EV) are a relatively contemporary and emerging technology in the transportation and power sectors, with several economic and environmental advantages. However, there are still challenges associated with EV charging depending on on-grid electricity. University buildings that consume a lot of energy continue to rely on the grid and/or conventional fuel for consumption. In addition, EV Charging will create more challenges in meeting the demand; therefore, utilizing university rooftops for EV charging has high prospects of meeting the additional energy demand. In Malaysia, no such research has been presented that has explored the possibility of using academic institute rooftops for BIPV installation for EV Charging in terms of energy and environmental standpoint. The current study analyzes and evaluates a rooftop grid-connected Building Integrated photovoltaic (BIPV) system for generating electricity and EV charging at the University Malaysia Pahang, Malaysia, for EV charging. The system’s energy output has been simulated using the PVSyst in two scenarios, i.e., fully integrated with no ventilation and free mounted with air circulation. It was found that 7000 m2 of the selected building’s rooftop area could be used for panel installation. The panels’ total capacity was 1.069 MW, with total annual electricity production of 1587 MWh and 1669 MWh in respective scenarios. The proposed BIPV plant would reduce GHG emissions of 60,031 tons of CO2e in scenarios 1 and 61,191 tons of CO2 in scenario 2 compared to the emission produced by coal plants for the same amount of annual energy generation.

An integrated framework for feasibility analysis and optimal management of a neighborhood-scale energy system with rooftop PV and waste-to-energy technologies

Hybrid energy systems with renewable energy penetration have become popular solutions to improve energy security and realize the carbon neural target in urban areas. In this paper, a holistic framework is proposed for the sustainable development of a neighborhood-scale energy system integrating rooftop PV and waste-to-energy technologies. Under this framework, potential assessment of local renewable energy, optimization approach, and sensitivity analysis are integrated for the optimal design and management of the hybrid energy system with uncertain analysis. Besides, the economic, efficiency, and environmental performance under grid-connected and off-grid operation modes are compared. This proposed framework is applied to a neighborhood area in Beijing. The results show that the grid-connected hybrid energy system will still rely on traditional energy supply with low cost but great carbon emissions. In the off-grid mode, 11 % of the rooftop area will be encouraged to deploy PV panels, which satisfying 39 % of the total electricity demand. Moreover, although decreasing the PV capital cost, raising the electricity price, and increasing carbon emission penalty cost will stimulate the development of local renewable energy, compulsive renewable energy penetration policy is more effective to promote the traditional energy system transformation and reduce carbon emissions.

Barriers to implementing poverty alleviation through livelihood strategies: A participatory analysis of farming communities in Ethiopia’s upper Blue Nile basin

Poverty is multi-dimensional global challenge that impedes individual and community capacities to satisfy basic needs. These capacities are shaped by locally configured institutional and biophysical processes that are often hidden from external researchers and practitioners. To explore this worldwide aspect, we adopt participatory rural appraisal (PRA) methods to expose barriers to implementing livelihood strategies to address poverty in Ethiopia’s upper Blue Nile basin, where 85 % of the population are subsistence farmers reliant on local ecosystem services (ES). We identify local barriers to poverty alleviation in three steps. First, we classify major ES-livelihood interrelationships among communities of Debre Mawi catchment in upper Blue Nile. Secondly we assess ongoing struggles in these interrelations using combined biophysical and social assessment criteria to evaluate how poverty relates to current patterns of ES management. The analysis identifies complex interdependencies between livelihoods and regulating (crop pest controls), provisioning (water, land, and feed availability, soil fertility) and cultural (top-down ES management, population growth) ES that create bottlenecks to effectively ‘lock in’ poverty. Thirdly, we identify potential new ES management strategies, focused on dry season water availability. We conduct participatory field experiments on rooftop water harvesting to show this is a promising approach for increasing water availability to enhance agricultural production. Depending on the rooftop area, our modelling suggests that farmers can improve household income by US$136– 14,876 from 5 months beef fattening and US$69–7704 from 4 months sheep fattening. Except these specific livelihood strategies, the findings are replicable to the world’s ES-dependent regions.

A framework to estimate the large-scale impacts of energy community roll-out

The gradual enactment of legislation for energy communities in individual European countries has increased the public awareness of these novel concepts. While the establishment of individual, isolated energy communities is unlikely to have any far-reaching effects, it is presumed that the large-scale roll-out will indeed significantly impact different stakeholders. Since the diffusion of energy communities is expected to gain momentum within the next years, this study aims to provide a framework to assess the impact of a large-scale roll-out of solar-PV based energy communities. This nine-step framework provides guidance for determining the number of buildings per type and roof tilt, assessing the usable rooftop area for PV installation and realistically installed PV capacities, estimating the number of future residential PV systems based on renewable expansion plans, determining the shares of buildings to be equipped with PV systems, setting up model energy communities, and upscaling. The nine-step framework is not only described theoretically but also applied to Austria as a case study. Thereby, specific focus is put on Austria's rural areas and thus the single-family building stock. Results indicate the impact of a large-scale roll-out of renewable energy communities on participants' electricity bills, electricity suppliers' sales, and grid operators revenues due to reduced grid tariffs for inner-community electricity transfer. The ability to determine the future impacts of energy community roll-out supports stakeholders in their proper planning towards an energy landscape that includes energy communities.

Geospatial Assessment of The Potentials of Rooftop Rainwater Harvest at The Federal University of Technology, Akure, Nigeria

Recent reports reveal water shortage at the Federal University of Technology, Akure, (FUTA), Nigeria, with possibilities to worsen if adequate measures are not taken. This research focuses on the assessment of the potential of an alternative source of water supply the Roof Top Rainwater Harvest (RTRWH) at FUTA. This study goes beyond the determination of the potential volume of RTRWH by proposing a storage plan for the RTRWH based on geospatial analysis. Data collected for the study are rainfall data covering 19 years (2000-2018), High-Resolution Satellite Image (HRSI), Ground Control Point (GCP), attribute data, Landsat 8 and Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM). The rooftop areas were extracted by processing HRSI using ArcGIS software. The volumes of the RTRWH for each building were computed with the rooftop area, precipitation amount and roof's runoff coefficient of the rooftop material as variables. Suitable locations for siting the storage tanks were proposed based on Multi-Criteria Decision Making (MCDM) and geospatial analysis. Result obtained from the study reveals that the total area of rooftop catchment for all buildings considered is 164,246 m2. The study suggests 9 locations suitable for collecting and storing the harvested RTRW. The potential average daily, average monthly and total annual volumes of RTRWH are approximately 607 m3, 18,473 m3 and 221,681 m3 respectively, and thereby could potentially provide ~ 41% of water demand in addition to the existing water supply sources in FUTA. The RTRWH is therefore recommended as an alternative water source at FUTA.

Power to the city: Assessing the rooftop solar photovoltaic potential in multiple cities of Ecuador

Abstract Solar energy plays a crucial role in helping cities to decentralize energy production and thus decarbonize the energy mix. Reliable resource assessments are needed to support the deployment of solar power systems, especially in cities of developing countries where large solar potential remains untapped. The aim of this work is to assess the potential of rooftop solar photovoltaic (PV) in three populated cities in Ecuador’s mainland (Quito, Guayaquil and Cuenca) and in the Galapagos Islands. The assessment involves (i) the estimation of the available rooftop area based on geographic information system data, (ii) the calculation of energy yield based on hourly satellite-derived irradiance and meteorological data, and (iii) the economic feasibility assessment in terms of levelized cost of electricity (LCOE) compared to representative electricity tariffs. In addition, a sensitivity analysis is carried out to assess the variability of the estimated technical and economic potential with respect to changes in the input parameters. The results reveal a total available rooftop area of about 144 km2, mainly concentrated in urban parishes. The estimated energy yield is 16.94 ± 3.38 TWh/a, which could cover almost twice the annual energy consumption in 2019 of the study areas. The economic assessment shows that the LCOE ranges between 7.65 and 21.12 USD cents/kWh. However, the comparison of LCOE against representative residential tariff suggests that rooftop PV technology is not cost-competitive under most of the financial scenarios. The findings from this study will be of interest for local authorities and other decision makers to design policies and financing strategies to increase the penetration of rooftop PV and thus exploiting the large potential assessed in the study areas. The described methodology can be used for assessing the potential in other regions of Ecuador and thereby support the diversification and decarbonization of the energy mix in the country.

Investigation of PV utilizability on university buildings: A case study of Karachi, Pakistan

This study aims to investigate the utilizability of Photovoltaic (PV) application by qualitative and quantitative examination of hurdles on the rooftops of university buildings. The rooftops of university buildings were investigated with the help of remote sensing technique. Site surveys were also conducted to validate data. Utilizable rooftop area, available for PV application was determined by identifying restrictions, their respective coefficients and utilization factors. PV∗SOL software was utilized to simulate the rooftop PV application on university buildings and it was found that university buildings have the potential to generate 5389.2 MWh/year with an annual specific yield of 1336.6 kWh/kWp. Environmental analysis was also conducted whose results revealed that PV utilization can save 63,727.05 tons of CO2, 1.89 tons of CH4, 0.27 tons of N2O, 970.05 tons of SO2 and 590.12 tons of NO emissions in 25 years. Economic assessment was also carried out in which levelized cost of electricity, discounted payback period, benefit to cost ratio, net present value and internal rate of return were determined as 0.05 USD/kWh, 11.17 years, 1.4, USD 2,682,508.01 and 11.81%, respectively. This research can benefit public and private sectors to capitalize their buildings’ rooftops for reducing energy and environmental challenges.

The plant and faunal species composition and diversity on rooftop farms: Seasonal variation and the effects of site and surrounding characteristics

The importance of human-dominated green spaces for biodiversity support is increasing. With the popularity of rooftop farms to grow healthy and local food, can rooftop farms provide wildlife habitats? This study conducted a year-round survey on eight rooftop farms to reveal (1) plant and faunal species composition and diversity of the rooftop farms, (2) variations in plant and faunal species composition by site and the four seasons, (3) effects of site and surrounding characteristics on faunal species composition and diversity, and (4) examine whether higher taxa was adequate in indicating species-level faunal species composition on rooftop farms. This study used visual observation and pitfall trap methods to conduct a faunal species survey twice a season; and recorded plant species and their blooming status in each survey. Arthropods were the survey target, and Molluscs found in the cultivation area were also recorded. The season averages in plant species number and blooming species were 30–50% and 20–30% of the total number of plant species in a year. Generalist species dominated rooftop farms. Site and seasons significantly affected faunal species composition and diversity. The site characteristics significantly affected the rooftop farms' faunal species composition and diversity, but the surrounding characteristics almost had no effects. The larger rooftop area led to a larger cultivation area, resulting in more plant and blooming species and attracting more faunal species. Humans managed the vegetation on the rooftop farms might form a distinct habitat. Family-level performed well as a surrogate in indicating faunal species-level composition on rooftop farms.

Rooftop rainwater harvesting for sustainable water usage in residential buildings for climate resilient city building: case study of Rajshahi, Bangladesh

PurposeThe effects of population growth in the developing world and climate change have increased the stress on available water resources. The majority of Rajshahi city, Bangladesh, is facilitated with groundwater withdrawal. As Bangladesh is a country of monsoon climate, reserved rainwater can be contributed as an alternative to extracted groundwater. This study aims to develop a framework for rooftop rainwater harvesting (RRWH) for domestic purposes and estimate the appropriate size of the storage tanks and their costs required to fulfill the annual drinking and cooking water demands through RRWH in Rajshahi city of Bangladesh.Design/methodology/approachA total of 100 single-story residential dwellings with varying rooftop areas were surveyed for the projection of RRWH potential. The relationship between the size and cost of a water tank and the rooftop areas of different houses is expressed using a general mathematical equation. Cost estimates for the proposed RRWH system for all houses have been completed, and a cost model illustrating the relationship between rooftop or catchment area and associated cost of RRWH system has been developed.FindingsThis study reveals that a maximum of 110.75 m3/year rainwater can be collected from a 100 m2 rooftop area of Rajshahi city. Moreover, this study finds that such harvesting of rainwater can reduce municipal water supply to the extent of almost 75%. Water samples collected from rooftops also revealed that if germs were removed through bacteria treatment, the collected rainwater potentially can be used for drinking and cooking purposes.Originality/valueThe novelty of this study is that it focused mainly on how significant RRWH can be to meet people’s daily required amount of water for household purpose and ascertain the cost reduction using the RWH method. This paper also is unique as it assessed the volume of the storage tank that is sufficient to distribute the necessary amount of water for drinking and cooking purpose as a sustainable alternative source in the dry season.

An estimation framework of regional rooftop photovoltaic potential based on satellite remote sensing images

This paper proposes a comprehensive framework for estimating the regional rooftop photovoltaic (PV) potential. The required rooftop information is extracted from Gao Fen-7 satellite images. In particular, the rooftop area is obtained using a semantic segmentation network. The azimuth and inclination angles are calculated based on the digital surface model. In addition, to improve the accuracy of the economic evaluation, buildings are divided into commercial and industrial buildings and residential buildings. Based on the difference in the roof inclination, the rooftops can be divided into flat roofs, on which the PV panels are installed with the optimal inclination angle, and sloped rooftops, on which the PV panels are installed in a lay-flat manner. The solar irradiation on the plane-of-array is calculated using the isotropic sky translocation model. Then, the available installed capacity and generation potential of the rooftop PV is obtained. Finally, the net present value, dynamic payback period, and internal rate of return are used to evaluate the economic efficiency of the rooftop PV project. The proposed framework is applied in the Da Xing district of Beijing, China, with a total area of 546.84 km2. The results show that the rooftop area and available installed capacity of PV are 25.63 km2 and 1487.45 MWp, respectively. The annual rooftop PV generation potential is 2832.23 GWh, with significant economic returns.

Perturb and Observe Parameter Tuning to Harvest Thermal Energy from Solar Radiation at Rooftop and Attic Area: A Comparative Study

Perturb and Observe Parameter Tuning to Harvest Thermal Energy from Solar Radiation at Rooftop and Attic Area: A Comparative Study

Rooftop rainwater harvesting and artificial roundwater recharge - a case study: Thanh Xuan district in south of Hanoi

Groundwater over-exploitation in the south of Hanoi has formed depression cones and accelerated land subsidence. Thanh Xuan district is one of the most suffered areas in the south of Hanoi. Artificial groundwater recharge (AGR) is an effective solution to mitigate those negative impacts. This study aims to evaluate the potential of rooftop rainwater harvesting (RRH) for AGR in the Thanh Xuan district. The prospect of RRH for the study area is estimated based on the average annual rainfall for the period 2008-2018 and the total rooftop area of selected buildings. The rooftop area is determined by analyzing satellite images and using the built-in tool in Google Earth. Field site investigation and measurements confirmed this estimation. Rainwater samples were taken for quality assessment. This assessment was conducted by measuring pH, EC, TDS, turbidity of rainwater in the field and analyzing NO3-, NO2-, PO43-, SO42- and Cl- contents in the laboratory. Moreover, to propose an effective AGR system, the maximum harvested rainwater and the recharge capacity of an injection well were estimated for the Golden Land building. The results show that 397 selected buildings can be used to collect rainwater. The total rooftop area of these 397 buildings is 262,645.8 m2, and that can contain 385,930.5 m3 of rainwater a year. The field measurement and analysis results indicate that rainwater quality meets the current standards appropriate for AGR. The AGR using rooftop rainwater will contribute to increasing groundwater level, reducing land subsidence, and mitigating urban flooding for Thanh Xuan and similar areas.

Optimizing the Potential of Solar Energy PT PJB UP Muara Karang Rooftop Area Using HelioScope

Year after year, there has been a rise in use of electrical power. The industrial, home, commercial, and public sectors accounted for 234,617.88 GWh of PLN's electrical energy sales in 2018. Meanwhile, the household, industrial, commercial, social sector, government office buildings, and public street lighting consumed 2,857.06 GWh of electrical energy in DKI Jakarta. The majority of the energy resources required by interconnected networks are fossil (coal). As a result, a future alternative to fossil fuels is required. Optimizing solar energy that may be employed in urban settings is one of the uses of renewable energy. The building sector consumes up to 40% of the total annual energy. By installing a renewable energy system on the roof of PT PJB Muara Karang power plant unit. The solar power plant energy potential on the roof of PT PJB UP Muara Karang administration building was simulated with HelioScope and using Quantitative Descriptive Method to maximize the rooftop area by installing 143 solar panel modules. which is capable of supplying 75.11 percent of the energy needs at PT. PJB UP Muara Karang.

Dynamic simulation of hydrogen-based off-grid zero energy buildings with hydrogen storage considering Fanger model thermal comfort

In this study, some locations with different climates, off-grid zero energy buildings with hydrogen energy storage systems are designed, and transient analysis is conducted. These considered buildings supply their electricity consumption without using the electrical grid and PV panels or wind turbines. Also, they supply thermal comfort to occupants by using a vapor compression chiller and humidifier. Domestic hot water of occupants is supplied using solar collectors. For analyzing building's performance and objectives achievement, TRNSYS software is used. Also, for evaluating occupant thermal comfort, the Fanger model is used. The considered building is a one-story building with a 150 m2 area. Four occupants are considered. Both of them are seated at rest, and another is seated with light working such as typing. Using the Fanger model equation and MATLAB software, the thermal comfort of occupants is determined. For domestic hot water consumption, verified profiles that vary during 24 h of the day are considered. Achieved results show that for humid and cold cities, PV panels with an area of 73 and 76 m2 can be supplied the required electricity of considered building with four occupants and battery state of charge is higher than 50% and 10%, respectively. Moreover, with a suitable air conditioner system, the predicted percentage of dissatisfied (PPD) can be lower than 12% and 8% for humid and cold cities. Therefore, the building can be converted to a zero-energy building using its rooftop area.

Solar Energy Modeling and Mapping for the Sustainable Campus at Monash University

An increase in energy demands and positive public acceptance of clean energy resources have contributed to a growing need for using solar energy in cities. Solar photovoltaic (PV) deployment relies on suitable locations with high solar energy potential. In the urban context, building rooftops are often considered one of the most available locations for solar PV installation. This work demonstrates a new geospatial-method for spatiotemporal modeling and mapping solar energy potential based on a high-resolution (0.2 m) digital surface model (DSM) and solar radiation dataset. The proposed method identifies building rooftops with a high solar energy potential by using the Solar Analyst (SA) model. The results show that 93.5% of the rooftop area has high solar energy potential in the study area. The annual averaged sum of solar irradiation values is estimated to be 1.36 MWh/m2. In addition, the study showed that sloped rooftops facing to the north received up to 30% more incoming solar radiation than other rooftops with different geometry and orientation. The results are validated using recorded energy output data from four existing solar PV systems in the study area. The return on the initial investment of PV systems installation is estimated to be from four to five years.

Estimation of Rooftop Solar Power Potential by Comparing Solar Radiation Data and Remote Sensing Data—A Case Study in Aichi, Japan

There have been significant advances in the shift from fossil-based energy systems to renewable energies in recent years. Decentralized solar photovoltaic (PV) is one of the most promising energy sources because of the availability of rooftop areas, ease of installation, and reduced cost of PV panels. The current modeling method using remote sensing data based on a geographic information system (GIS) is objective and accurate, but the analysis processes are complicated and time-consuming. In this study, we developed a method to estimate the rooftop solar power potential over a wide area using globally available solar radiation data from Solargis combined with a building polygon. Our study also utilized light detection and ranging (LiDAR) data and AW3D to estimate rooftop solar power potential in western Aichi, Japan, and the solar radiation was calculated using GIS. The estimation using LiDAR data took into account the slope and azimuth of rooftops. A regression analysis of the estimated solar power potential for each roof between the three methods was conducted, and the conversion factor 0.837 was obtained to improve the accuracy of the results from the Solargis data. The annual rooftop solar power potential of 3,351,960 buildings in Aichi Prefecture under Scenario A, B, and C was 6.92 × 107, 3.58 × 107, and 1.27 × 107 MWh/year, estimated using Solargis data after the adjustment. The estimated solar power potential under Scenario A could satisfy the total residential power demand in Aichi, revealing the crucial role of rooftop solar power in alleviating the energy crisis. This approach of combining Solargis data with building polygons can be easily applied in other parts of the world. These findings can provide useful information for policymakers and contribute to local planning for cleaner energy.

Reliability and Economic Analysis of a Rainwater-Harvesting System for a Commercial Building with a Large Rooftop Area

The water shortage problem faced by many countries requires a practical engineering solution. The reliability analysis of a rainwater-harvesting system (RWHS) installed at a commercial building of AEON Taman Universiti located in Johor Bahru, Malaysia, was based on the rainfall pattern, rainwater use, and rainwater storage tank. An economic analysis using the net present value (NPV), return on investment (ROI), and benefit–cost ratio (BCR) was performed to assess the optimal management of a RWHS installed during the construction and retrofitted after the operation of a commercial building. The results showed that the balance of water supply and demand is reliable for implementing a RWHS and the optimal management of a 1000 m3 RWHS tank installed during construction could be more promising than that retrofitted after operation of the AEON Taman Universiti commercial building. The operation of a RWHS installed during the construction of a building is obviously more feasible because the NPV, ROI, and BCR values tend to be high. The reliability and economic analysis of RWHS installed during construction and that retrofitted after operation of a commercial building demonstrated the benefit of RWHS installation will contribute to effective water management as part of future building design.

Vectorized rooftop area data for 90 cities in China

Reliable information on building rooftops is crucial for utilizing limited urban space effectively. In recent decades, the demand for accurate and up-to-date data on the areas of rooftops on a large-scale is increasing. However, obtaining these data is challenging due to the limited capability of conventional computer vision methods and the high cost of 3D modeling involving aerial photogrammetry. In this study, a geospatial artificial intelligence framework is presented to obtain data for rooftops using high-resolution open-access remote sensing imagery. This framework is used to generate vectorized data for rooftops in 90 cities in China. The data was validated on test samples of 180 km2 across different regions with spatial resolution, overall accuracy, and F1 score of 1 m, 97.95%, and 83.11%, respectively. In addition, the generated rooftop area conforms to the urban morphological characteristics and reflects urbanization level. These results demonstrate that the generated dataset can be used for data support and decision-making that can facilitate sustainable urban development effectively.

Optimum tank size for large rainwater harvesting system

AbstractThe efficiency of rainwater tank systems depends on tank size, local climate, and potable water demand. This study investigates optimum tank size to maximize water saving potential in semi‐arid Southern California using a simple daily water balance model. The model evaluates the performance of various tank varying sizes collecting rainwater from 10,000 m2 rooftop area of a college campus for the local historical dry, average, and wet years. Results show tank sizes of 130–630 m3 having 100% capture efficiency but system reliability varies from 2.8% to 37.75% in the dry to wet years, respectively. An optimal tank size range is derived from the reliability curves that represent the tank system performance in the local climate. Optimal tank size ranges from 180 to 240 m3, which can capture more than 64% of the roof runoff and thus the campus can reduce on an average 10% of urban water demand.

Utilising high-fidelity 3D building model for analysing the rooftop solar photovoltaic potential in urban areas

There are multiple approaches of estimating solar power generation by rooftop solar photovoltaic (PV) systems. Methods processed using GIS as well as 3D models provide the most reliable and accurate results. However, with the restriction of a limited detail 3D model area, estimations on a regional scale are hard to achieve. The regional power potential can be predicted by identifying the correlation of rooftop areas and the shadowing effect changing between the Level of Detail (LOD)1 and LOD2 models in the case study areas. This research considers the aspects and angles of the rooftops, to try and not only figure out the optimal PV installation conditions but also to make a general estimation for optimal angle, 2-axis solar tracking as well as total solar radiation received scenarios. The results of the research indicate that the optimal annual angle is 177° and 13° in aspect and slope degree, respectively, and the improvements of power generation under those three scenarios increase from about 2 to 16% in the test area, respectively. This research also showed that the power potential in partial small areas had the same tendency as the whole region even though each part of the small area had uneven city pattern. Additionally, different from most of the study, north-facing rooftops had been proved to have the strong potential to be developed as a solar power PV panel site and should not be neglected from the whole PV system.