Roof Area Research Articles

Combining Hydrologic Analysis and Life Cycle Assessment Approaches to Evaluate Sustainability of Water Infrastructure: Uncertainty Analysis

The goal of this research is identifying major sources of uncertainty of an environmentally-sustainable urban drainage infrastructure design, based on hydrologic analysis and life cycle assessment (LCA). The uncertainty analysis intends to characterize and compare relative roles of unreliability, incompleteness, technological difference, and spatial and temporal variation in life cycle impact assessment (LCIA) data, as well as natural variability in hydrologic data. Uncertainties are analyzed using a robust Monte Carlo simulation approach, performed by High Throughput Computing (HTC) and interpreted by Morse-Scale regression models. The uncertainty analysis platform is applied to a watershed-scale LCA of rainwater harvesting systems (RWH) to control combined sewer overflows (CSOs). To consider the watershed-scale implications, RWH is simulated to serve for both the water supply and CSO control in an urban watershed in Toledo, Ohio, USA. Results suggest that, among the studied parameters, rainfall depth (as a hydrologic parameter) caused more than 86% of the uncertainty, while only 7% of the uncertainty was caused by LCIA parameters. Such an emphasis on the necessity of robust hydrologic data and associated analyses increase the reliability of LCA-based urban water infrastructure design. In addition, results suggest that such a topology-inspired model is capable of rendering an optimal RWH system capacity as a function of annual rainfall depth. Specifically, if the system could capture 1/40th of annual rainfall depth in each event from rooftops, the RWH system would be optimal and, thus, lead to minimized life cycle impacts in terms of global warming potential (GWP) and aquatic eco-toxicity (ETW). This capture depth would be around 2.1 cm for Toledo (given an 85 cm/year rainfall and 200 m2 typical roof area), which could be achieved through an RWH system with 4.25 m3 capacity per household, assuming a uniform plan for the entire studied watershed. Capacities smaller than this suggested optimal value would likely result in loss of RWH potable water treatment savings and CSO control benefits, while capacities larger than the optimal would likely incur an excessive wastewater treatment burden and construction phase impacts of RWH systems.

Feasibility study of installation photovoltaic system at a university in Indonesia: A case study

Universitas Samudra (UNSAM) is one of the new state universities in Indonesia, located in Langsa City, Aceh Province. The masterplan for developing UNSAM projected to expanding access to higher education for secondary school graduates in the province by increasing the capacity through the construction of new buildings. The plan to construct green buildings inside the campus complex is simply an effort to achieve the UNSAM mission, which is, to become a green campus. There are nine buildings on the UNSAM campus with a total roof area reaching 11,232 m2, which is structurally suitable for solar photovoltaic installation. In Langsa City, for one year, the average exposure to sunlight is equivalent to about 7,860 hours. The average annual insulation at this location is around 5.0 to 6.5 kWh / m2 / day. This study focuses on the economic feasibility of solar photovoltaic systems on the UNSAM campus. Electricity production costs, which might have economic benefits, are obtained for Rp. 1, 990 / kWh. The results of the analysis concluded that the economic potential of installing a PV system is very dependent on the geography of the building and the direction of PV installation.

ANALISIS KONSERVASI AIR BERBASIS ZERO RUN OFF (STUDI KASUS KAWASAN BLOCK OFFICE BALAI KOTA AMONG TANI KOTA BATU)

The development of Batu as a tourist and agropolitant city has led to some concern, such as water resources. The number of springs has increasingly declined due to the conversion of forest into agriculture land, residential, and tourist sites. Therefore, it’s necessary to maintain equilibrium through the process of extracting and replenishment of rain water by absorbing it into soil pores as water conservation efforts. This study examines the analysis of water conservation based on the concept of zero runoff, located in the Block Office area. It is expected to become input for the Batu City Government and be developed in those area. The analysis of surface runoff is calculated by Rational Method. The dimension of recharged well is calculated by using SNI method 03 2453 2002. The magnitude of design discharge obtained with 5 years return period is 111,408 mm. Reharged well is planned with 5 meters height and 1 meter diameter. Recharged well used for 100 m roof area is 1. Water conservation technology by using recharged well is able to collect runoff from the roof, while retention pool collect and absorb runoff from the parking area, road, and yard.

Experimental Study on Wind Load Characteristics Caused by Wind Damage in Vulnerable Areas of Low-rise Building Roofs

Through the wind tunnel test on the opening of different locations and local areas in vulnerable areas of low-rise building roofs, the distribution characteristics of wind pressure inside and outside the roof caused by roof damage. The results show that the influence of the wind direction angle on the internal pressure caused by the wind is obvious, and the internal pressure caused by the opening on the leeward surface is small and the change law is obviously different from that on the windward surface. The correlation coefficient on the inner side of the roof opening is higher than that on the side of the unopened roof, and the correlation between wind pressure on the measurement points near the opening is larger than other regions.

A New Methodology to Assess Building Integrated Roof Top Photovoltaic Installations at City Scales: The Tropical Coastal City Case

AbstractAs a consequence of the warm and humid climate of tropical coastal regions, there is high energy demand year-round due to air conditioning to maintain indoor comfort levels. Past and current practices are focused on mitigating peak cooling demands by improving heat balances by using efficient building envelope technologies, passive systems, and demand side management strategies. In this study, we explore city-scale solar photovoltaic (PV) planning integrating information on climate, building parameters and energy models, and electrical system performance, with added benefits for the tropical coastal city of San Juan, Puerto Rico. Energy balance on normal roof, flush-mounted PV roof, and tilted PV roof are used to determine PV power generation, air, and roof surface temperatures. To scale up the application to the whole city, we use the urbanized version of the Weather Research and Forecast (WRF) model with the building effect parameterization (BEP) and the building energy model (BEM). The city topology is represented by the World Urban Database Access Portal Tool (WUDAPT), local climate zones (LCZs) for urban landscapes. The modeled peak roof temperature is maximum for normal roof conditions and minimum when inclined PV is installed on a roof. These trends are followed by the building air conditioning (AC) demand from urbanized WRF, maximum for normal roof and minimum for inclined roof-mounted PV. The net result is a reduced daytime Urban Heat Island (UHI) for horizontal and inclined PV roof and increased nighttime UHI for the horizontal PV roof as compared with the normal roof. The ratio between coincident AC demand and PV production for the entire metropolitan region is further analyzed reaching 20% for compact low rise and open low rise buildings due to adequate roof area but reaches almost 100% for compact high rise and compact midrise buildings class, respectively.

Nonlinear evolutionary swarm intelligence of grasshopper optimization algorithm and gray wolf optimization for weight adjustment of neural network

The advent of new data-mining techniques and, more recently, swarm-based optimization algorithms have antiquated traditional models in the field of energy performance analysis. This paper investigates the potential of two state-of-the-art hybrid methods, namely grasshopper optimization algorithm (GOA) and gray wolf optimization (GWO) in improving the neural assessment of heating load (HL) of residential buildings. To achieve this goal, eight HL influential factors including glazing area distribution, relative compactness, overall height, surface area, roof area, wall area, orientation, and glazing area are considered for preparing the required dataset. A population-based sensitivity analysis is then carried out to use the best-fitted structures of each ensemble. The results showed that utilizing both GOA and GWO algorithms results in increasing the accuracy of the neural network. From comparison viewpoint, it was found that the GWO (error = 2.2899 and correlation = 0.9551) surpasses GOA (error = 2.4459 and correlation = 0.9486) in adjusting the computational parameters of the proposed neural system.

Study on Implementation of Rooftop Photovoltaic Power Plant as an Effort to Attain a Sustainable Campus

The concept of Green Campus means that the University has implemented environmental preservation activities, energy efficiency, and deliver comfortable conditions to support learning and work activities. The activity to harvest renewable energy is one of several approaches towards a sustainable campus. This study aims to analyze the technical and economic feasibility of a solar power plant erected on the roof of buildings within the campus area. Based on the University of Samudra development master plan, it has carried a technical and financial feasibility study with the assists of the System Advisor Model (SAM) software. The analysis shows that the current roof area is possible to generate electrical power of 3 MW, with economic calculations of electricity production costs of 11.7 cents/kWh.

Study on Implementation of Rooftop Photovoltaic Power Plant as an Effort to Attain a Sustainable Campus

The concept of Green Campus means that the University has implemented environmental preservation activities, energy efficiency, and deliver comfortable conditions to support learning and work activities. The activity to harvest renewable energy is one of several approaches towards a sustainable campus. This study aims to analyze the technical and economic feasibility of a solar power plant erected on the roof of buildings within the campus area. Based on the University of Samudra development master plan, it has carried a technical and financial feasibility study with the assists of the System Advisor Model (SAM) software. The analysis shows that the current roof area is possible to generate electrical power of 3 MW, with economic calculations of electricity production costs of 11.7 cents/kWh.

Usable rainwater volume; results of a hydrological study conducted at the Universidad de Santander, Bucaramanga, Colombia

This study was carried out at the “Universidad de Santander”, in Bucaramanga, Colombia, to calculate the volume of rainwater capturable from the roofs of five campus buildings, as the blueprints for these surfaces were available to obtain their areas. Roof areas were first obtained for the Guane, Motilón, Arhuaco, Chibcha and Yariguíes buildings, from which rainwater can be captured. Intensity, duration, and frequency curves from the “Instituto de Hidrología, Meteorología y Estudios Ambientales” were then used to calculate a design flow, yielding the diameter of the pipe necessary to evacuate the water captured. In addition, data from the “Universidad de Santander” meteorological station was evaluated to obtain monthly rainfall figures. The highest-yielding structure was the Motilón building, with approximately 80 m3 in the months of May and November, 2018, as this structure has the largest roof area, and the area experienced its greatest quantity of rain during these months. The total accumulation predicted by the study was 1837.96 m3 annually, sufficient to suggest the possibility of its use in restrooms, gardens, and floor washing at the “Universidad de Santander”, Bucaramanga, Colombia. The volume of water calculated is variable on a yearly basis, and was estimated by means of one year of rainfall readings from the university’s meteorological station. Hydraulic structures designed for the purpose of capturing this water would require a specific study, taking into account the records of other nearby meteorological stations, and making necessary provision for the storage of water in excess of expected volumes.

Determining Rainwater Harvesting Storage Capacity with Particle Swarm Optimization

A reduction in the amount of available clean water is a universal problem, and the harvest of rainwater is one of the methods that can solve this issue. In this study, the smallest reservoir capacity that can collect rainwater falling on roofs is defined, using daily rainfall data spanning a 32-year period for the cities Burdur, Isparta, and Antalya. Reservoir capacities with different roof areas being able to serve different needs are expressed using graphics. Particle swarm optimization (PSO) is compared with classic methods like the mass curve method, and the minimum flaw method. While the mass curve method provides the best results among the classic methods, PSO offers similar results. This study is divided into two sections. The first section includes the optimization model, which is defined for annual fixed needs. The software created in this section is compared with the results obtained from the other methods and its accuracy is proven. In the second section, the software is created according to users’ changing needs, which is not available for the other methods. The biggest advantage of the software is to be able to define optimum reservoir capacity in accordance with changing water needs and user risk perception. In this paper, a sample study is conducted to show the difference between fixed needs and changing needs, with the advantage acquired via optimization according to changing needs being shown.

The development of private green open space in the residential area in Makassar

This study aims to 1) analyze the need for private green open space and community participation in the development of private green open spaces; 2) conceptualize the development of Private Green Open Space in accordance with the conditions of the land in the residential area of Makassar. This research is descriptive in nature. This research was conducted on residential in Tamalanrea and Mamajang Sub districts. To collect the data, it was done through collection observation, interviews, and questionnaires. Respondents involved were household heads who were randomly selected. Then, data were analyzed by quantitative and qualitative analysis. The results of the study indicate that the two research locations have the same development direction. The concept of developing private green open spaces is analyzed based on the availability of land, which is directed to the area of land for residential areas that still has open space and to the roof area for residential areas that do not have open space. In the green garden type land, it is developed a pot scaping, while in the roof field the type of green layout developed is a green roof.

A critical comparison of methods to estimate solar rooftop photovoltaic potential in Switzerland

To understand the opportunities and challenges of large shares of solar photovoltaics (PV) in our electricity mix, various large-scale studies of PV potential on building roofs have been conducted in recent years. The use of different datasets, methods and spatio-temporal resolutions leads to widely varying results, making a comparison across different studies intrinsically difficult. In this work, six studies carried out in Switzerland are compared in a quantitative way, in order to understand how different methods impact the potential estimates. We observe a strong trend towards increasing spatial and temporal resolutions, using larger and more accurate datasets for the analysis. While the earliest study relies on rules of thumb, later studies use data-driven estimations, enabled by the use of Machine Learning, scalable algorithms and powerful computational engines. Our analysis shows that the largest differences are caused by the source of the solar radiation input data, the computation of shading effects on rooftops and the estimation of available roof area for PV panel installation. The latter is the most uncertain parameter in the presented studies and offers opportunities for future work.

Experimental investigation on the effects of inter-layer gaps on wind loads of cantilevered stadium roofs

To meet the ventilation requirement, an engineer needs to design the cantilevered roof of a stadium as a layered one with gaps between the layers. In order to further understand the wind resistance performance of such structures, a wind tunnel test was carried out on a 1:200 scaled stadium model considering two roof inter-layer cases: opened gaps and blocked gaps. The laws of lift force coefficients and net wind pressure coefficients were compared for these two gap conditions. The study results indicate that the roof experiences larger mean lift force on both top and bottom surfaces when the inter-layer gaps are blocked. However, the roof gaps can reduce the fluctuating lift force on top roof surface and the net fluctuating lift force, weakening the vibration of the flexible large-span roof. The negative pressures (suctions) in the inner and middle roof areas on the leeward side decrease for the blocked gap case. The positive pressure in the outer roof area generally increases along the windward direction, while the negative pressure decreases in other wind directions, when the roof inter-layer gaps are blocked. In the highest and transition roof areas, the fluctuating pressures increase for most wind directions, while in the lowest roof area, they decrease when the roof inter-layer gaps are blocked. The test and analysis results provide a valuable basis for the wind design of this kind of roof structures.

Assessing reliability of rainwater harvesting systems for meeting water demands in different climatic zones of Iran

Assessing the performance of rainwater harvesting systems, which is one of the effective ways to cope with the water shortage crisis, leads to better management of these systems. In this paper, the reliability of rainwater harvesting systems and the overflow ratio of storage tanks were investigated for different climatic conditions, different volumes of tanks, and different roof areas. The results indicated that in the cities of Rasht, Sari, Tabriz, and Yazd, using a 10-m3 tank, non-potable water needs of a four-person family can be supplied from a 100-m2 roof area for 67.3, 42.98, 12.07, and 1.35% of the days during a year. Further, if a 1-m3 tank is used in Rasht, 50.67% of the total harvested water will be overflowed, which would decrease to 19.21% if the 10-m3 tank is replaced. For Tabriz, the ratio of overflow from the 5-m3 tank was zero, but for the city of Sari, even with use of a 10-m3 tank, 0.73% overflow occurred. In addition, for Yazd city, using a 1-m3 tank, an overflow of 48.4% occurred, but when the volume of the tank was increased to 2 m3, there was no overflow. For the city of Tabriz, the ratio of overflow from the 5-m3 tank was zero, but for the city of Sari, even using a 10-m3 tank, 0.73% overflow occurred. For a constant volume of storage, as long as the average rainfall of the area was high, the ratio of overflow was also elevated. The ratio of overflow, from the highest to the lowest, was related to the temperate climate of the Caspian Sea and the pseudo-Mediterranean climate, moderate and humid climate, mountainous climate, and desert hot and dry climate, respectively.

Target-based visibility assessment on building envelopes: Applications to PV and cultural-heritage values

Solar energy applications have, in recent years, become a common element in the urban landscape, especially on roofs and facades. However, it is important that the integration of solar energy in the built environment do not distort the fabric or expression of the existing building envelope, not at least in areas of high cultural-heritage values. The aesthetics depend, to a large extent, on how visible the new technology, such as photovoltaic (PV) panels, is. This paper describes a method for visibility assessment of building envelopes. It is referred to as target-based as it, in contrast to previously reported methods, bases the assessment from the perspective of the building envelope itself, rather than possible vantage points on the ground. The method was evaluated for two Swedish cities; Stockholm and Visby. In Stockholm, each building was evaluated based on its cultural-heritage values, solar irradiation and visibility. Deploying PV only on the roofs with the lowest cultural-heritage values, with insolation > 900 kWh/m2, and with no visibility from ground, results in a total PV yield of up to 2% of the total electricity demand. In Visby, various definitions of the vantage area were evaluated, from which the building envelope can be seen. It was found that the choice of vantage area greatly impacts the solar energy potential. If the vantage area is defined by the public domain, i.e., streets and other public open spaces, the non-visible roof area doubles compared to if all ground/terrain defines it. Compared to previous studies, the use of a vantage area, instead of discrete vantage points, seems to result in higher visibility of the roofs.

Assessing the Potential for Potable Water Savings in the Residential Sector of a City: A Case Study of Joinville City

The objective of this study is to evaluate the potential for potable water savings by using rainwater in the residential sector of Joinville, a city located in southern Brazil. Data on roof areas of residential buildings were obtained from the Joinville city council. By considering the roof areas and typologies of residential buildings, representative models were created. The following parameters were used to determine the rainwater tank capacity: the number of dwellers; the total daily water demand per capita; and the rainwater demand. To carry out the simulations for determining the optimal rainwater tank sizes and potential for potable water savings, the computer program Netuno was used to run 33,720 different scenarios. By considering the occurrence percentage for each representative building model (weighted average), the average potential for potable water savings by using rainwater was calculated. The average potential in the central region of Joinville was 18.5% when there is rainwater use only in toilets, and 40.8% when there is rainwater use in toilets and washing machines. The rainwater harvesting system showed a better performance for a rainwater demand equal to 20% of the total daily water demand. The results indicate the necessity to properly size rainwater tank capacities to meet water demands, thereby encouraging more people to adopt rainwater harvesting as an alternative source for non-potable water in buildings. The demand for rainwater should be carefully evaluated, especially in multi-story residential buildings, due to the low availability of roof areas.

A study of the dynamic movement rule of overlying strata combinations using a short‐wall continuous mining and full‐caving method

AbstractAt present in China, short‐wall working face coal‐mining methods are among the main methods used for the high‐efficiency recoveries of boundary coal pillars and residual pillars. In traditional short‐wall mining methods, overlying roofs are supported by coal pillars. However, issues such as the excessive number of coal pillars, low coal recovery efficiency, large areas of hanging roof arches, etc, have been encountered. In view of the aforementioned issues of the current short‐wall mining technology, this study took the short‐wall mining of the Yujialiang Mine in the Shendong mining area as the project background. The study then proposed a judgment method for the key stratum on the working face of the mine using a short‐wall continuous mining and full‐caving method. The proposed method was based on the theory of elastic plates and was verified using the theoretical analysis results of similar material simulation experiments. FLAC 3D software was adopted to analyze the stress and displacement evolution processes of the overlying rock strata during the advancement of the working face using a short‐wall continuous mining and full‐caving method. The results showed that the short‐wall continuous mining and full‐caving method not only had the ability to improve the recovery rate, but was also able to realize the effective control of the roof areas, thereby avoiding any large areas of hanging arches. The short‐wall continuous mining and full‐caving method is potentially of important significance for the improvement of coal recovery rates, as well as for the safe and highly efficient mining of boundary coal pillars and residual pillars in mines under special conditions.

Energy and indoor climate measurements in Denmark’s first energy neutral block of flats

Denmark’s first energy neutral multi-family house, BOLIG+, is constructed at Søborg near Copenhagen and consists of 10 flats divided on 4 floors. BOLIG+ was the first attempt to construct a multi-family block of flats that complies with a set of criteria and dogmas that defines the BOLIG+ concept. Energy production on the building needed e.g. to meet not only the buildings energy demand, but also the residents’ electricity energy use for light and appliances. Additionally when exchanging energy with the grid, energy “sold” should have at least the same exergy level as energy “bought”. Building multi-family houses that are energy neutral on annual basis, is, therefore, much more difficult than for a single-family house. One of the reasons for this is the small amount of roof area available (per. dwelling) for local electricity production compared to the roof area of a single-family house. Last, but not least, the buildings was constructed under normal economical market conditions, i.e. without any subsidies for the construction.When designing the building, the normal standard conditions for calculating the buildings energy performance was offset in order to ensure better coherence between the design energy demand and the following energy measurements. The indoor temperature was set higher, and so was the domestic hot water demand. Additionally, free loads (gains) from persons, light and appliances was set lower than the standard.To meet the goal of being energy neutral, several low-energy solutions are used e.g. compact thermal envelope; highly insulated constructions; highly insulating windows; hybrid decentral ventilation; heat recovery on grey wastewater; PV on facades and roof; buffer zones. Additionally, an electric battery was installed to improve the economy of the PV installation by optimizing the amount of electricity used inside the meter (tackling the feed-in tariff issue).This paper presents results from 1½ year of measurements of energy performance and indoor climate carried out in the building during the period 2017-2018.Measurements of energy consumption showed that if the PV installation has produced as expected and the residents had used electricity as expected, the building would have been only 11% from being energy neutral.Indoor climate measurements show high temperatures in a large share of the period.

Coal Seam Roof: Lithology and Influence on the Enrichment of Coalbed Methane

To identify the lithology of coal seam roof and explore the influence of these roofs on the enrichment of coalbed methane, low-frequency rock petrophysics experiments, seismic analyses and gas-bearing trend analyses were performed. The results show that the sound wave propagation speed in rock at seismic frequencies was lower than that at ultrasound frequencies. Additionally, the P-wave velocities of gritstone, fine sandstone, argillaceous siltstone and mudstone were 1,651 m/s, 2,840 m/s, 3,191 m/s and 4,214 m/s, respectively. The surface properties of the coal seam roofs were extracted through 3D seismic wave impedance inversion. The theoretical P-wave impedance was calculated after the tested P-wave velocity was determined. By matching the theoretical P-wave impedance of the four types of rocks with that of the coal seam roofs, we identified the lithology of the roofs. By analyzing known borehole data, we found that the identified lithology was consistent with that revealed by the data. By comparing and analyzing the coal seam roof lithology and the gas-bearing trends in the study area, we discovered that the coal seam roof lithology was related to the enrichment of coalbed methane. In the study area, areas with high gas contents mainly coincided with roof zones composed of mudstone and argillaceous siltstone, and those with low gas contents were mainly associated with fine sandstone roof areas. Thus, highly compact areas of coal seam roof are favorable for the formation and preservation of coalbed methane.

Analysis of building energy efficiency dataset using naive bayes classification classifier

The phenomenon of global warming has become a very important and serious issue in recent years. One effort to reduce emissions by applying the green architecture concept to buildings. The purpose of this paper is to classify energy efficiency data sets. The method used by the Naïve Bayesian Classifier algorithm. Results obtained by Kappa statistics Y1 (0.3357) and Y2 (0.4203); Mean absolute error Y1 (0,0368), Y2 (0,0335); Root mean squared error Y1(0,1491), Y2(0,1412). The results of the analysis showed overall height, relative compactness, wall area, and glazing area affected the heating and cooling loads, while the surface area affected the heating load and the roof area affected the cooling load.