Roof Area Research Articles

Relevance of monocrystalline and thin-film technologies in implementing efficient grid-connected photovoltaic systems in historic buildings in Port Fouad city, Egypt

This study explores the potential of integrating PV technologies on pitched roofs in Port Fouad City, Egypt, that represent the dominant style of heritage buildings in coastal cities in the Mediterranean Sea zone, considering the challenges that affect the relevance of preserving the architectural identity. This research starts with the filtration step to shortlist the relevant PV technologies, followed by the simulation step using PVsol Premium for all roof surfaces. Finally, an optimization step is performed to achieve the optimum design. According to the simulation analysis, monocrystalline and thin-film technologies dominate the results. In contrast, installation of polycrystalline technology is inadequate in such type of villas under similar weather conditions in terms of their performance ratio (PR), PV generated energy, and annual yield. Moreover, despite the light weight of the thin-film tile, we observe that the monocrystalline array is more preferable than the thin film owing to its lightest overall weight and least covered area. The optimization results indicated that monocrystalline provides the highest PR (79.4%) and annual yield (1715.1 kW h/kWp) with the smallest covered roof area (7.2 m2) and total weight (78.2 kg), whereas thin-films are more relevant in terms of color complement based on architectural theme.

Study on the Dip Angle Effect of Asymmetric Deformation and Failure of the Gob-Side Coal–Rock Roadway in Gently Inclined Coal Seam

In order to reveal the influence law of coal seam dip angle on the stability of the surrounding rock of the gob-side coal–rock roadway in a gently inclined coal seam (GCRGICS), the deformation characteristics of the surrounding rock under four different coal seam dip angles of this kind of roadway were studied by field investigation, theoretical analysis and numerical simulation. The results showed that, with the increase of the coal seam dip angle, the amount of the roadway roof subsidence and the deformation of the upper and lower side arc triangle coal along the coal–rock interface increased, and the maximum deformation was 479 and 950 mm, respectively, and the maximum slip deformation area gradually shifted from the upper side arc triangle coal to the lower side arc triangle coal. The asymmetric deformation characteristics of the surrounding rock became more and more obvious. The asymmetric deformation rate of the GCRGICS showed a V-shaped variation relationship with the coal seam dip angle, when the coal seam dip angle was 10°, the asymmetric deformation rate was the minimum, only 1.1%. The plastic zone of the surrounding rock expanded with the increase of the coal seam dip angle, and the new extension range was mainly located in the roof area of the roadway.

Two new species of Clessinia (Gastropoda: Stylommatophora: Odontostomidae) from Argentina

Two new species of Odontostomidae are described from Argentina: Clessinia juramentoensis sp. nov. (near Juramento river, Metán Political Department, Salta province) and Clessinia subcylindrica sp. nov. (from Chancani, Pocho Political Department, Córdoba province). Both species are compared with all the species of Clessinia represented in Argentina; images of the related species are presented. C. juramentoensis is characterised by its sub-pyriform shell, small, lustrous to naked eye; secondary ureter opening between the middle and the distal area of the lung roof; penis inner wall with penial area IV occupying 1/3 of penis total length. C. subcylindrica is characterised by its small sub-cylindrical-globose shell, penial area II sculptured with numerous, long, strongly contracted lamellae, penial area III with a pilaster formed of a single fold, much contracted, becoming scalloped. The purpose of this study is to provide complete data on shell morphology and internal anatomy, as well as the distributional information on both species.

Potentials of hydroactive lightweight façades for urban climate resilience

AbstractExtreme heat and heavy rainfall events with severe inundations have a significant impact on urban architecture, resulting in considerable personal injuries and material damage. Nowadays, the proportion of façade surface in urban areas with tall buildings is substantially larger than the proportion of horizontal roof or ground surface areas. A high leverage effect on climate resilience and sustainability of buildings and cities can therefore be attributed to the building envelopes. Whereas the majority of existing façades are designed to provide only minor qualities at a district or urban level, research at the Institute for Lightweight Structures and Conceptual Design (ILEK) at the University of Stuttgart focuses on development of a new type of hydroactive lightweight façades incorporating climate change mitigation and adaptation strategies. A textile‐ and film‐based façade element calledHydroSKINis capable of providing a retention surface on the envelope of the building. With a minimal amount of embedded mass, energy, and CO2emissions, the façade add‐on element is suitable for both new and existing buildings.HydroSKINcombines rainwater harvesting (RWH) and run‐off water reduction by retaining the precipitation water that strikes the façade with a time‐delayed evaporative cooling (EC) of the building and its environment.

Solar Power Potential from Industrial Buildings and Impact on Electricity Supply in Bangladesh

Bangladesh has a rapidly increasing population and coupled with healthy economic growth, is resulting in a rising energy demand. The country also aims to increase its renewable share of electricity to 10% by 2030. However, due to limited wind resources, solar energy seems to be most appropriate to deliver such a target. However, in a land-scarce country, this presents a major challenge, which this work aims to partially address. Being a globally leading producer of commodities, Bangladesh has a considerable number of large manufacturing plants with appropriate roofs that could be used for deploying solar energy conversion systems at scale. A methodology is presented which identified and assessed 6045 such plants, which have roof areas ranging from 100 m2 to 50,000 m2, and modelled the deployment of solar photovoltaic (PV) technology that can provide power through site available grid infrastructure. Such deployment takes advantage of net metering regulations to enhance the case for such power generation. A techno-economic assessment was also presented, addressing how such utilisation can support the 10% renewables target of Bangladesh without impacting scarce lands. The results showed that around 7.4 GWp of PV capacity can be achieved on such roofs with a corresponding annual electricity generation of 11 TWh. This represents more than 6% of Bangladesh’s current electricity consumption and more than half of the 2030 target. Furthermore, the deployment will save 13,000 acres of farmland, as well as providing power through site available grid infrastructure saving on investment if the systems are deployed on land. These results are likely to influence policy to support the presented proposition, not only in terms of increasing the renewable energy share in the country’s electricity supply mix but also in conserving much-needed land for agriculture.

Pioneer attempt of incorporating four variables in generalised equations for predicting water savings through rainwater tanks

ABSTRACT This paper presents the development of robust equations for calculating expected water savings through rainwater tanks, which are dependent on annual rainfall, rainwater demand, tank size and roof area. The city of Brisbane (Australia) was selected for this purpose. A modified version of the earlier developed daily water balance model, eTank was used to calculate annual water savings under different scenarios using daily rainfall data collected from the Australian Bureau of Meteorology. Several sets of charts on varying roof size, demand, tank size and annual rainfall were produced from the simulated results. Eventually, the sets of charts were converted to a single generalised equation, each for one of the four selected regions in Brisbane. Results from the developed equations were seen matching with the model (eTank) simulated results. Such equations can be easily incorporated into mobile apps or computer programs to help quick calculations for expected water savings.

A feasibility study for PV installations in higher education institutions – a case study

ABSTRACT Connecticut (CT) stands among the top five states for its high electric rates due to limitation in transmission facilities and storage of natural gas. Photovoltaic systems are a growing alternative energy source that reduces the electricity demand and hence higher education institutions should start implementing these technologies to reduce the burden of paying more for electricity bills. The primary objective of the study was to analyze the economic feasibility of solar photovoltaic systems (PV) in higher education institutions in CT. To perform the objective, several economic parameters were calculated and the annual electricity revenue for the University of New Haven was determined and applied to the entire state of Connecticut. The study was expanded to other states in the U.S. by normalizing the available roof area, electricity rate, and solar index by each state. The total electricity generation for various regions by normalization was estimated to be about $651.2 Million annually. With the normalization ratio obtained, one can identify the total power generation in other regions of the U.S. beforehand while considering installation of PV systems. Results from the study regarding the total revenue reveal that the Southwestern and Western regions of the U.S have more solar power generation capacity due to high solar radiation. A life cycle analysis for solar panel was performed at the end to determine how beneficial it is to adopt solar PV in the long run. Considering the recycling of solar PV at the end of its life, additional 4.33% of the total revenue will be expected as benefit, which is quite significant for sustainable option to invest. This reveals that the solar PV is one of significant energy sources and cost saving factors.

Evaluation of the band-shaped isthmuses in the mesiobuccal root canal system using micro-computed tomography.

This micro-computed tomography (micro-CT) study analyzed band-shaped isthmuses having their floor at the apical third of the mesiobuccal roots of maxillary molars in terms of 2D and 3D morphological parameters. A total of 199 maxillary first molars were scanned with micro-CT. Twenty-seven specimens, confirmed to have a band-shaped isthmus, were further examined in terms of the isthmus length, volume, structure model index (SMI), and surface area. The distance of apical foramina of mesial canals from the isthmus floor and major-minor diameters, roundness, perimeter, and area of the isthmus roof and floor were compared. Statistical analyses were performed with descriptive statistics and t-test with a 5% significance threshold. The band-shaped isthmus frequency was 13.5% and its length reached up to 5.5mm. The distances of the apical foramina of mesiobuccal canals (MB1 and MB2) from the isthmus floor were similar (p > .05). Isthmus roof and floor showed significant differences in terms of their major diameter and area (p < .05), whereas their minor diameter, roundness, and perimeter values were similar (p > .05). The band-shaped isthmuses are not rare and can reach through the half of the root length with oval cross-sections in the floor and roof anatomy. The distance between the isthmus floor and apical foramina did not differ between MB1 and MB2. The band-shaped isthmus morphology contributes to the complexity of the apical anatomy of maxillary first molar teeth with various lengths and diameters.

Assessing the Potential of Implementing a Solar-Based Distributed Energy System for a University Using the Campus Bus Stops

Large educational facilities hold great potential for the implementation of solar-based distributed energy systems. The aim of this paper is to present a prototype and an assessment of a solar-based bus shelter photovoltaic system intended to be implemented at a campus scale that serves as an energy-distributed system. The National Autonomous University of Mexico (UNAM), a campus with an area of 7.3 km2 and bus stops’ roof area availability of around 1100 m2 was selected as a case study. The proposed system, apart from considering on-site generation, also considers an increase in end-use services such as the installation of television screens for information, charging docks, surveillance cameras, internet service, and lighting. For the assessment, a load facility survey and an estimation of the baseline energy use was conducted based on two demand use conditions, corresponding to 12 and 24 h for different archetypical stations. It was found that the baseline annual energy consumption for all the bus stops represents from 55–111 MWh. In this paper, an initial prototype of a solar-based bus shelter PV system is presented, and an assessment is carried out to understand its potential application at a large scale. The analysis shows that energy use in the retrofitted stations would rise to 167 MWh/year; however, apart from covering on-site demand, the system has the capacity to generate an additional 175 MWh, feeding nearby university buildings. It is calculated that the system could save around 130 t CO2e annually. The economic analysis shows that the project has a discounted payback (DPB) of almost 9 years and an internal rate of return (IRR) of 5.9%; however, in scenarios where renewable generation and carbon incentives are applied, this improves the project’s DPB to 6 years and the IRR to 13%.

Efficiency and sustainability assessment of evaporative cooling of photovoltaics

The cooling of PV has been shown to increase electricity production. Among passive techniques, evaporative cooling has one of the greatest potentials. In this work, the efficiency and sustainability of this technique have been investigated for various climatic conditions. In-situ experiments were conducted to develop parametric models for PV cell temperatures and back surface convective heat transfer coefficient. Experiments have revealed an up to 20.1 °C lower peak PV temperature and up to 9.6% increased electric power. Year-round analysis was made for eight cities to determine the required roof size to capture precipitation and the volume of rainwater storage for sustainable evaporative cooling. The study shows that sustainable PV evaporative cooling is possible in cities with temperate and continental climates, where 1–3 m2 of roof area and 50–150 l of rainwater storage are needed for 1 m2 of PV. The annual electricity production can increase by 5.9–9.4 kWh/m2a, which is a 3.6–4.6% increase. In the semi-arid climate of Lampedusa, a roof above 4 m2 and a storage of up to 500 l per m2 of PV are required. In the desert climate of Almeria and Athens, sustainable evaporative cooling is not feasible.

GIS- and ICPR-Based Approach to Sustainable Urban Drainage Practices: Case Study of a Development Site in Florida

Stormwater control is an urgent concern in cities where the increased impervious surface has disrupted natural hydrology, particularly causing a reduction in groundwater recharge which is the source of potable water supply for many communities. Water managers are increasingly turning towards infiltration-based stormwater management options (ISMOs) to help minimize flooding and mitigate the impact of urbanization on the local hydrologic systems. This paper offers a unique hydrologic and hydraulic (H&amp;H) modeling approach using the Geographic Information System (GIS) and Interconnected Pond and Channel Routing (ICPR) software to help quantify the associated flood stage and groundwater recharge benefits of using ISMOs. The proposed approach incorporated ICPR percolation links and utilization of the curve number and Green-Ampt infiltration methods into the case study design, as well as an analysis of the effectiveness of including low-impact development practices. This analysis shows a 13–36% reduction in stormwater volume leaving the proposed site when percolation links were utilized to account for percolation from the proposed ISMOs. These reduction provides an indirect estimate of groundwater recharge benefits. The conversion from impervious parking to a pervious one and inclusion of rainwater harvesting from the roof area resulted in a further reduction in peak stages ranging from 1.20 to 7.62 cm.

Improvement of Rainwater Harvesting Analysis Through an Hourly Timestep Model in Comparison with a Daily Timestep Model

For the analysis of rainwater tank outcomes, some researchers used monthly water balance model, which ignores an important factor such as overflow from the tank. Recently, to improve the accuracy of such analysis facilitated by the availability of daily rainfall data, many researchers started using daily timestep models. In the daily timestep models, the daily rainwater demand is deducted from the available storage, once in a day and there are debates on whether to apply that deduction at the beginning of the day or at the end of the day. Moreover, there is significant diurnal variation of water demand, which can not be accounted for in a daily timestep model. To overcome this, current study investigates an hourly timestep model considering hourly rainfall data and hourly variable rainwater demands. Hourly rainfall data was collected from the Australian Bureau of Meteorology for a raingauge station located in Melbourne. An earlier developed daily water balance model was converted to hourly scale incorporating hourly variable rainwater demands. Model simulated results for three distinct years (dry, average and wet) were compared with the results using a daily timestep model with the same data. Variations of water savings and overflow amounts are presented under four combinations of roof area and daily rainwater demand with tank sizes varying from 2500 L to 20,000 L. It is found that in all the selected years, the daily timestep model underestimated the annual water savings compared to the hourly timestep model and the highest difference was estimated to be 13,750 L for a smaller tank size connected with a bigger roof having higher rainwater demand.

A comprehensive study of the potential and applicability of photovoltaic systems for zero carbon buildings in Hainan Province, China

Energy balance in the building industry and the potential of building PV systems are indispensable to achieve carbon peaks and carbon neutrality in Hainan Province. This research investigated load matching for different types of buildings and the electricity generation potential of building PV systems in Hainan Province. The tilt angle, orientation, PV conversion efficiency and available area of the building were adopted as research parameters to analyze the chance of realizing zero carbon in the building industry. The potential of roof PV systems and economic analysis in Hainan Province were studied. The results show that when a high-performance PV system (20%) is utilized, the electricity demand of buildings can be covered, and 86.9% of the total electricity demand of Hainan Province can be provided by roof PV systems. If all available roof area was used appropriately, carbon emission reduction is up to 13.49 million tons CO2 every year. The cumulative carbon emission reduction could be 408.7 million tons CO2 by using roof PV systems during 2020–2060. The initial cost and pay back period were 117.4 billion CNY and 6.3 years, respectively. All residential buildings, office buildings and small hotels are able to achieve an energy balance when the PV conversion efficiency is 20%. Electricity generation reaches the maximal value when the tilt angle is 15°. When the tilt angle is in the range of 0° to 30°, energy generation is larger than 270 kWh/m2a, and the difference is less than 5%. Electricity production on the east and west facades is greater than that on the south façade. This research provides some references for using building PV systems in Hainan Province.

Evaluation of Rainwater Harvesting Systems in Three Major cities of New South Wales

Rainwater harvesting (RWH) systems are becoming more popular to reduce pressure on mains water as well as to serve as a sole freshwater supply system in rural areas. Australia is a large continent with highly variable rainfall and hence performance of a RWH system varies from location to location. This paper presents reliability and water-saving potential of a RWH system in three major cities namely Sydney, Newcastle and Wollongong of New South Wales (NSW) State of Australia. A python-based daily water balance model is built to analyse the performance of a RWH system, which uses rainfall, loss, water demand and roof catchment data. To enable selection of ideal rainwater tank size for the selected locations, three different water uses (toilet and laundry, irrigation, and combined use) and five tank sizes (1, 5, 10, 20 and 30 kL) are considered. It is found that the rainwater tank size is influenced by roof area, number of users, water demand and rainfall characteristics. This study will help in decision-making regarding implementation of a RWH system in these Australian cities. This research also contributes towards achieving water related sustainable development goals (SDG).

Investigation of PCM thermal effectiveness towards an optimised design of cooling building envelope

The buildings are responsible to 40% of the global greenhouse gas emission. To tackle the climate change, the development of sustainable building is urgent. Phase Change Material (PCM) as a potential material was suggested to integrate in building envelope to maintain a constant room temperature. This paper investigated the thermal performance of the PCM in building envelope at tropics and optimizes the cooling effect by manipulating melting temperature, thickness, position, and the type of PCM. ANSYS FLUENT software is used to model the 2D cross-sectional area of the steel roof and brick wall. With the input of 2 normal days outdoor temperature, the results of simulated indoor surface temperature are compared with the control set to determine the optimum setting while monitoring on its cost-effectiveness. The results showed that the optimum melting temperature of PCM is 29 °C for brick wall application and 31 °C for steel roof application. In normal day, PCM can reduce the peak indoor surface temperature up to 4 °C. Although in the evening, PCM delays the time for the room to cool off, but for the normal warehouse operating hours this is not affecting the thermal comfortability of the workers.

Analisa Perencanaan Pembangkit Listrik Tenaga Surya Atap dengan Sistem Hybrid di PT. Koloni Timur

&lt;p&gt;This study discusses the Planning of a Rooftop Solar Power Plant with a Hybrid System at PT East Colony Kudus. The&lt;br /&gt;model is set as a PLTS whose solar panels are adjusted to the roof area of the building. This PLTS is functioned as a new&lt;br /&gt;renewable energy resource (EBT) in the form of a hybrid between PLTS and PLN's electrical energy source, this is done to&lt;br /&gt;help supply electricity. Parameters determined include: roof area, solar panel capacity, inverter capacity, battery capacity&lt;br /&gt;and payback period. The results show that PLTS with a total of 80 solar panels installed with a capacity of each panel 405&lt;br /&gt;Watt peak, then obtained a power capacity of 32.4 kilo Watt peak which is divided into 5 arrays, with a solar charger controller&lt;br /&gt;and inverter using a 10kW capacity of 5 units, 80 batteries with a capacity of 400Ah. So that PLTS is able to contribute 39.3%&lt;br /&gt;of the total power needed by PT East Colony (electric power from PLN is 60.7%). This hybrid payback period will return after&lt;br /&gt;8 years and 7 months.&lt;/p&gt;

Obtaining the NZEB target by using photovoltaic systems on the roof for multi-storey buildings

Photovoltaic (PV) systems are often used for the attainment of the NZEB (Net Zero Energy Building) target. The lack of sufficient roof area for the plant installation is, however, a common issue that limits the spread of this technology mainly in urban areas characterized by high density of buildings. This work evaluates the possibility of obtaining the NZEB target for residences and offices in Mediterranean area, using only “on site” PV systems, i.e., on the roof slab, considering different typologies of building. An in-depth analysis is provided for obtaining the building geometric parameters that would allow to establish, in the first stages of the design process and avoiding dynamic energy simulations, whether it is possible to achieve energy self-sufficiency for a certain building, taking into consideration the characteristics of the plans and the number of floors. The results show that, for the investigated square-based residential building, the energy self-sufficiency, and therefore the NZEB target, is obtainable up a maximum of 7 levels (6 levels for rectangular shape building, 5 for L and courtyard shapes), while, for another case study building intended for offices, the energy self-sufficiency is obtainable up to a maximum of 7 levels. For early design analyses about geometric characteristics and intended use of new buildings, it would be possible to use the results reported in this study to achieve a first evaluation of NZEB target attainment.

Evaluation of environmental comfort in a social housing prototype with bioclimatic double-skin in a tropical climate

The aim of this paper is to broaden understanding of the social housing prototype that students and researchers at the University of Seville developed in response to tropical climate conditions to achieve the maximum level of hygrothermal comfort through the use of passive retrofit strategies.This prototype, known as Aura 1.0, was presented at the Solar Decathlon competition where hygrothermal conditions inside the prototype were monitored over a ten-day period. Nevertheless, as the monitoring period of the environmental conditions was so reduced, the aim of this research is to assess the environmental behaviour of the prototype for a full year, under tropical climate conditions. To do so, energy and environmental simulation instruments will evaluate the performance of the architectural proposal and its passive construction systems, in particular the double skin designed with different objectives (architectural, construction, socio-economic).The simulation model has been verified by the data monitored during the exhibition phase and the performance of the building. Various hypotheses have been analysed which demonstrate that employing a double skin in the dwelling contributed to improving interior thermal comfort, especially in the roof area as opposed to the facades, given the sun's path at a latitude close to the equator.

Self-consumption possibilities by rooftop PV and building retrofit requirements for a regional building stock: The case of Catalonia

European Union policies are encouraging the implementation of renewable energies to reduce fossil fuels dependency. This is further motivated by the effects of global warming and the relevant temperature rise in large cities. Thus, it is increasingly important to analyze the large-scale potential of solar energy, making use of the roof availability for renewable energy generation in cities. Furthermore, it is important to couple this analysis with the energy demand of the buildings analyzing the self-consumption possibilities and help in the decision-making process in regional investments. The proposed methodology estimates and matches the roof potential for electricity generation by PV and the building's energy demand, including the building characteristics as a novelty. As a result, we calculate the self-consumption possibilities and the retrofit requirements of a selected housing stock. Our methodology starts with the quantification and classification of the residential stock. This includes the characterization of the types of dwellings in the regional residential stock, taking into account the size of the municipalities. Then the energy demand of the dwellings, depending on the characteristics of the buildings and the roof generation potential, is compared. Catalonia region (Spain), including the city of Barcelona is studied to show the contributions of this methodology to the energy transition. Results indicate that between 8 and 30% of the residential electricity demand of the municipalities can be covered by rooftop PV. Important energy retrofits (reductions of 80% of the energy demand) are required to approach the feasibility of self-consumption. Nevertheless, there is a limited potential impact in larger cities due to the reduced available roof area per habitant.

Damage Mechanism and Stress Distribution of Gypsum Rock Pillar Subjected to Blasting Disturbance

The room-pillar mining technology of underground gypsum resources results in numerous gypsum rock pillars for controlling and supporting mined gobs, which forms a large area of roof hanging gobs. Owing to weathering and mining activities, gypsum rock pillar damage and failure will occur, thereby inducing a large area of gypsum mined-gob collapse accidents and disasters. Blasting is vital to the stability of gypsum rock pillars and is indispensable in mining engineering. Based on field blasting tests and using wave velocity as the basic parameter to characterise the integrity of gypsum rock, the damage mechanism of gypsum rock pillars subjected to blasting disturbance is investigated. With ten blasting tests, the maximum damage rate is 7.82% along the horizontal direction of pillar, and 3.52% along the vertical direction. The FLAC numerical simulation calculation software is used to analyse the stress distribution law of gypsum rock pillars with disturbances of different strengths from different distances. As the disturbance strength increased, the stress increased with no clear linear relationship; as the disturbance distance increased, the stress decreased gradually with a linear relationship. All stress after disturbance is greater than the original static stress, and lower than the ultimate compressive strength. However, the correlation between blasting tests results and numerical simulation results is poor and is discussed for many factors. The results can provide important guidance and reference for clarifying the damage mechanism of gypsum rock pillars subjected to blasting disturbance, as well as reveal the collapse mechanism of gypsum mined gobs.