Roof Shape Research Articles

A Comparative Study of Cooling Performance and Thermal Comfort under Street Market Shades and Tree Canopies in Tropical Savanna Climate

Walking through street markets is the most popular outdoor activity in Thailand, promoting local economies and tourism. In the year-round hot and humid conditions, living outdoors with long heat exposure throughout the midday can result in heat-related illness. Artificial shade structures and tree shade canopies are typical cooling strategies to protect market sellers and pedestrians from direct sun exposure and improve outdoor human thermal comfort in the street market. This study investigates microclimate conditions and cooling benefits of typical street market shade structures with different settings—three roofing materials, two roof shapes, and surrounding trees with dense and sparse canopies. The dimension of the single artificial shade was 2 m × 2 m with heights varying 2–2.5 m. The vertical air temperature and sky view factor profiles were measured on winter and summer days. The calculated physiological equivalent temperatures (PET) and thermal comfortable hours beneath different shade structures were assessed using RayMan 1.2 software. A cluster of trees with a dense canopy provided more effective cooling (with a satisfied thermal condition of 9 h) than artificial shade structures. Thermal conditions under the galvanized steel roofing and HDPE tarpaulin plastic roofing shades were cooler than those of polycarbonate roofing shade. Meanwhile, the space beneath the sparse tree canopy had the warmest condition. The temperature reductions beneath the artificial shade structure varied throughout the day, with the maximum reduction occurring during midday and the lowest reduction found in the late morning and late afternoon. Our study demonstrates that the tree canopies and artificial shade structures had limited application for providing comfortable conditions throughout midday. To reduce such extreme heat, a combination of shade structures with other cooling techniques is suggested, which should be the focus for further studies.

Facilitating vehicle-integrated photovoltaics by considering the radius of curvature of the roof surface for solar cell coverage

By mounting photovoltaics (PV) on the roof of an electric vehicle (EV), solar energy can be used to supply a considerable portion of the energy demand of the EV. The roof is the best place for PV installation on the vehicle body because doors and engine hood have less yearly-average sunlight available and more stringent mechanical requirements. The roof of a modern passenger vehicle such as a sedan is not flat, and parts with high curvature or a significant slope do not need to be covered. However, there are no design rules available for mounting PV on a vehicle roof, such as determining the coverage ratio. In this study, the distributions of roof shapes and sizes were obtained from trace drawings of various commercially available passenger vehicles. This was then used to calculate the distributions of the mechanical (i.e., local curvature) and optical (i.e., local solar utilization rate) properties. Based on the results, general guidelines were developed, including a potential coverage ratio of 96% for a hemispherical roof with a radius of curvature of 1 m. These guidelines have already been successfully demonstrated and prototyped with a small module.

IMPACT ANALYSIS of CYLINDRICAL STEEL WATER STORAGE TANKS UNDER the SEISMIC ACTION

Cylindrical steel liquid tanks are widely used to store various liquids such as water, oil and industrial chemicals. In recent years, they are used in nuclear power plants for cooling purposes. Petroleum or other hazardous chemicals in steel liquid tanks can cause large financial and environmental damage due to damages in tanks during the earthquake. The main goal of this paper is to reveal buckling shape of cylindrical steel tanks with nonlinear seismic analysis according to roof shapes. Roof shapes were determined as open-top, flat-closed, conical-closed and torispherical-closed tanks. For this aim, El-Centro earthquake recording of 0.22 seconds was used for determine the significant shell buckling events. In addition, this earthquake values are ideal for impact analysis because ANSYS Workbench “Explicit Dynamics” tool provides very good results in the dynamic analysis of structures under destructive and short-term forces. In order to provide the interaction between the water and the tank wall, the "Eulerian Body" mesh technique is preferred in “Explicit Dynamics” model. As a result of this study, many collapse events were determined due to seismic ground motion in cylindrical steel liquid storage tanks. If the tank was closed in the shape of a torispherical, less buckling could occur in the tank.

Research on Roof Structure and Determination of Working Resistance of Shallow Buried Single Key Stratum Based on Grid Drillhole Field Method

Abstract The roof structure of the stope is the core of revealing the weighting mechanism and determining the working resistance of support. The Shenfu Dongsheng coal field of China has abundant reserves of shallow coal seam. The phenomena of strong ground pressure and step subsidence caused by the mining of shallow buried single key stratum (SBSKS) poses a serious threat to the fragile environment. Revealing the shape and movement process of roof structure of SBSKS is the primary prerequisite for ensuring safe mining of working face. Firstly, the field measurement technology of the space grid-like drill field was developed to construct vertical holes and incline holes in the auxiliary headgate gateway and tailgate airway ahead of the working face and to obtain the measured data of the broken position and vertical displacement of the roof by the drilling peep and multipoint displacement. Secondly, the key parameters of the stope roof were analyzed by the grid drillhole filed method, for example, the inclined roof break angle, the rotation angle, the thickness of equivalent immediate roof (EIR), and the roof structure-articulated level and shape. Then, we combined with the mining face comparison of compression laws revealing the time and space relationship between the movement of the roof structure and the roof weighting, and three more dangerous states of the roof were determined. Finally, the roof structure of SBSKS is moved upward through the field research on the 22201 working face, the “high step rock beam” structure and the advanced breaking position of the roof are obtained, and the calculation equation of the support resistance in large mining height face is given. The research results provide scientific guidance for the safety of SBSKS coal seam and provide technical support for green mining in ecologically fragile mining areas.

Influence of piston crown shape with different positions of spark plug and fuel injector, %EGR, and fuel system control on emissions from modified GDI engines compared with a base diesel engine

In this study, the combustion chamber profiles were developed for spray, wall, and air-guided gasoline direct injection (GDI) engines. For each combustion chamber geometry of GDI engine, the piston crown surface was modified, from hemispherical bowl, to trapezoidal bowl, and a pent roof shape that included a scoop type bowl on one side (towards injector position) to impart better squish, swirl, tumble, and turbulence effects to improve the mixing characteristics. Also, the cylinder heads were modified for each combustion chamber geometry by changing the locations of the spark plug and fuel injector. Further, the fuel split injection timings with duration, ignition timing, and the percentage of exhaust gas recirculation were optimized to reduce an engine out emissions; especially soot and nitrogen oxides. Emission tests were conducted on the base diesel engine and the GDI engine with the three different combustion chamber geometries. It is clear from the results that the emission of nitrogen oxides in the wall-guided mode was reduced by 5% till 75% of the load when compared with spray-guided and air-guided combustion modes. Overall, the GDI engine with the wall-guided combustion chamber geometry produced better results at 150 bar fuel injection pressure when compared with the base diesel engine; nitrogen oxides emission was reduced from 377 to 77 ppm and soot emissions were reduced from 29.3 to 4.5 g/km at high torque.

Ventilation performance analysis on low-rise courtyard building for various courtyard shape factors and roof topology

Residential buildings in the street canyon are highly suffering from reduced natural ventilation since the surrounding buildings completely mask the window and door openings. For such buildings, ventilation through the roof is an excellent method, and the buildings with courtyard space are believed to provide good ventilation and comfort. However, proper designing of courtyard buildings is highly essential, and for that, a complete airflow study in and around the courtyard building is required. Hence, in this research work, a low-rise residential courtyard building is considered, and the influence of courtyard space shape factor and roof topology on the ventilation performance of courtyard buildings is studied. The airflow study is made with the aid of the computational fluid dynamics (CFD) technique. Grid sensitivity analysis, validation of CFD results with wind tunnel experiments, and repeatability error analysis on wind tunnel test rig are also conducted to ensure the reliability of CFD simulation results. From this analysis, the courtyard with a wider space entraps more air from the atmosphere, and the building with low height offers uniform airflow in the courtyard space. Roof topology significantly influences the airflow around the building. Among the analyzed roof shape, pitched roof shape seems to perform relatively better and enhance the indoor air velocity by 42% with reference to the building without courtyard space. Also, the thermal comfort index for the building with courtyard space is 1.16 whereas for a building without a courtyard is 2.42 on a 3 scale. The percentage dissatisfaction index (PPD) is 52.9% lesser in the building with courtyard space.

Associations Between Historical Redlining and Present-Day Heat Vulnerability Housing and Land Cover Characteristics in Philadelphia, PA.

Historical, institutional racism within the housing market may have impacted present-day disparities in heat vulnerability. We quantified associations between historically redlined areas with present-day property and housing characteristics that may enhance heat vulnerability in Philadelphia, PA. We used color-coded Home Owners Loan Corporation (HOLC) maps and tax assessment data to randomly select 100 present-day (2018-2019) residential properties in each HOLC grade area (A = Best; B, C, and D = Most hazardous; N = 400 total). We conducted virtual inventories of the properties using aerial and streetview imagery for land cover and housing characteristics (dark roof color, flat roof shape, low or no mature tree canopy, no recently planted street trees) that may enhance heat vulnerability. We used modified Poisson regression models to estimate associations of HOLC grades with the property characteristics, unadjusted and adjusted for historical and contemporary measures of the neighborhood sociodemographic environment. Compared to grade A areas, higher proportions of properties in grade B, C, and D areas had dark roofs, low/no mature tree canopy, and no street trees. Adjusting for historical sociodemographics attenuated associations, with only associations with low or no tree canopy remaining elevated. Adjusting for present-day concentrated racial and socioeconomic deprivation did not substantially impact overall findings. In Philadelphia, PA, HOLC maps serve as spatial representations of present-day housing and land cover heat vulnerability characteristics. Further analyses incorporating longitudinal data on urban redevelopment, reinvestment, and neighborhood change are needed to more fully represent complex relationships among historical racism, residential segregation, and heat vulnerability.

Reconstructing historical 3D city models

Historical maps are increasingly used for studying how cities have evolved over time, and their applications are multiple: understanding past outbreaks, urban morphology, economy, etc. However, these maps are usually scans of older paper maps, and they are therefore restricted to two dimensions. We investigate in this paper how historical maps can be ‘augmented’ with the third dimension so that buildings have heights, volumes, and roof shapes. The resulting 3D city models, also known as digital twins, have several benefits in practice since it is known that some spatial analyses are only possible in 3D: visibility studies, wind flow analyses, population estimation, etc. At this moment, reconstructing historical models is (mostly) a manual and very time-consuming operation, and it is plagued by inaccuracies in the 2D maps. In this paper, we present a new methodology to reconstruct 3D buildings from historical maps, we developed it with the aim of automating the process as much as possible, and we discuss the engineering decisions we made when implementing it. Our methodology uses extra datasets for height extraction, reuses the 3D models of buildings that still exist, and infers other buildings with procedural modelling. We have implemented and tested our methodology with real-world historical maps of European cities for different times between 1700 and 2000.

КОНСТРУКТИВНЕ РІШЕННЯ ПОКРІВЛІ У ВІЗАНТІЙСЬКИХ ХРАМАХ СЕРЕДНЬО- ТА ПІЗНЬОВІЗАНТІЙСЬКОГО ПЕРІОДІВ

In this article, based on archaeological and hagiographic sources, the features of constructive solutions (techniques of construction and use of building materials) in the temples of the capital and provincial architectural schools of the middle and late Byzantine period were studied. The author focuses on the two main types of roofs of Byzantine temples – tiles and metal plates, the technology of their construction, roof shapes, the use of certain types of building materials and the specifics of using certain types of roofs in different regions of the Byzantine Empire. Each case of application of a certain technique / building material / type of roof is illustrated by the example of archeological finds or preserved mentions in the hagiographic literature. The study found that the most common version of the roof was ceramic tile, due to the cheapness of the material. A popular type for Byzantine roofs was a tile of weakly conical semi-cylindrical, sometimes flattened, shape; trapezoidal tile provided in the design of a wedge-shaped gutter for water drainage on the outside of the tile. It was found that the process of «assembling» the roof took place by connecting the tiles from the top elements (semi-cylindrical shape with a tooth-shaped end), which were driven between the already connected two tiles. During a study of the manufacture of ceramic tiles, it was found that the process was probably similar to the production of plinths (bricks) in the same kilns; instead, the main difference was that at the time of formation, trapezoidal, flat thin frames were used (so that the tile was formed on one side wider and narrower on the other – to overlap each other), and in the drying process these frames with clay were not placed on sand, and on a wooden board. The author also considered other variations of the tile – depending on the building material and shape. Thus, it was found that the material of the tile could not be limited to ceramics: in areas of construction, where there were no resources for the manufacture of ceramic tiles, stone was made and used. The most expensive and strongest variant of a material for a tile – metal – was chosen also because it was easy in processing. Particular emphasis in the study was placed on the use of metal plates for the roof. So the most popular material for this was lead – it melted at low temperatures, easily rolled into sheets (usually rectangular, but there were exceptions). The technique of construction of a roof with lead plates was that when superimposing plates, one overlapped another, for this purpose in places of seams they were bent and rolled. Lead for Byzantine construction was found to have been mined in several regions, including the northern Balkans, Pontus, and Macedonia. It is also noted that the use of lead plates for the roof contributed to the emergence and development of various forms of the roof (for example, the capital’s architectural school preferred a wavy surface).

The effect of courtyard buildings on the ventilation of street canyons: A wind-tunnel study

Using controlled tests in a wind tunnel, we simulated the pollution of four different street canyons formed by four 3D urban array models. The urban models differed by the geometry of roofs (pitched and flat roofs) and buildings (courtyard and solid buildings). We simulated traffic pollution from a ground-level source positioned in the middle of the street canyons. We show that the courtyard buildings significantly improve (by a factor of 1.3) the ventilation of the street canyons only in the cases with pitched roofs. We explain the differences between the ventilation performances of the street canyons by analysing the dynamics of the coherent structures. The buildings at the roof level shed two main vortex structures into the flow. However, the street canyon with pitched roofs and the courtyard buildings shed more stable structures that collide and penetrate deeper downstream near the wind-facing eaves. Near the pedestrian zone, ventilation is driven by advection, manifested as corner vortices at the street ends and flow convergence from the windward to the leeward side in the middle of the street canyons. The corner vortices are more pronounced in the courtyard buildings regardless of roof shape, resulting in higher concentrations than solid buildings.

Wind loads on multi-span roof buildings

This paper examines wind loads acting on multi-span roofs of low-rise buildings by performing wind tunnel tests with models whose parameters are roof shape (sawtooth, gable), roof slope (5°, 10°, 20°, 30°, 45°) and the number of spans (1–5). Large suctions can occur at either a high corner/edge or a low corner of sawtooth roofs, depending on roof slope and the location of roof span. Low corners of multi-span gable roofs experience large negative pressures on edge roofs of low-pitch roof slopes and on middle roofs of steeper roof slopes. Relatively large positive pressures on both sawtooth and multi-span gable roofs can occur at roof troughs of low-pitch roof slopes and their magnitude becomes larger as roof slope increases. For steeper roof slopes, large positive pressures are also observed at roof ridges of both roof shapes although their magnitude and the location of the roof span depend on roof shape. Both the size and the magnitude of suctions on walls between spans of sawtooth roofs increase with roof slope. Comparisons with ASCE7-16 design values were performed and the results imply that ASCE7-16 underestimates both positive and negative wind loads on most roof zones of multi-span roofs.

Analysis of Roof Collapse Cases Caused by Snow Loads in Russia (2001–2021)

Cases of building decay and structural damage caused by the impact of snow loads are registered every year throughout the world. Such destruction not only results in property loss, but also leads to human losses. A database on 266 cases of roof collapse caused by snow loads in Russia for the period from 2001 to 2021 was collated for this study. The data were analyzed by date and place of collapse, building data, and number of victims. The analysis showed that civilian buildings are the most vulnerable, comprising 78% of the total number of collapses, followed by industrial buildings with 15% and agricultural buildings with only 7%. The relationships between roof shape, roofing material, number of floors, and type of collapsed building were determined. The data processing results showed that low-rise residential buildings (one to two floors) with a gable roof covered with fiber cement should be considered the most vulnerable. A linear relationship was revealed between a collapse area of more than 150 m2 and the cumulative number of collapse cases. The obtained results have practical application for rating building vulnerability to natural hazards and assessing the risk of emergencies associated with snow loads.

Numerical simulation of a conical roofed low-rise building to estimate the wind pressure coefficients

The roof shape and the slope of the roof are both significant constraints for the protection of the structure against wind load. The present study aims to investigate the variation of wind pressure coefficients on the conical roof and to observe the wind behavior around the building. CFD (Computational Fluid Dynamics) software ANSYS has been used for modeling and simulation. It is found that the 35° roof slope is the optimum roof angle for the present study, as there is the least area-weighted average pressure coefficient for this roof angle. While the roof slope 30° is found the most critical roof angle in terms of wind load resistance among all the roof angles of the present study.

PASAR RAKYAT NATUNA

The market is a place where buyers and sellers meet to conduct buying and selling transactions of goods and services. The characteristic of a market is the existence of transaction or buying and selling activities. The market has at least three main functions, namely distribution function, price formation function, and promotion function. Natuna is an area where one of the sources of the regional economy relies on natural resources and tourism sector. Natuna supports an important role in both trade and service activities. Along with the development of trade and services activities in Natuna Regency, the development of facilities and infrastructure that support trade and services activities. The role of the market is very important for the Natuna community to make it easier for people to obtain the goods and services needed so that people in Natuna no longer go outside the island or out of town just to shop for clothes and basic daily necessities. The purpose of the design of Natuna People's Market is to produce the design of the people's market in Natuna Regency as a shopping center and trade center. The application of passive cooling in the design of Natuna People's Market is one of the objectives to solve design problems that serve to provide thermal comfort by maximizing natural delivery. The attraction of Natuna People's Market building is from the dynamic form of buildings following the concept of the roof shape of the traditional house in Riau Islands. Another application is in the secondary skin of the building in the form of mats using brown iron plate material to create a color that looks classic and neutral.

Pengembangan Taman Rendo Menjadi Taman Bermain Anak Di Kota Ende (Dengan Pendekatan Arsitektur Hijau)

Ende City is one of the cities in East Nusa Tenggara which has a children's playground called Taman Rendo. Rendo Park's initial function when it was built was as a recreation area with interesting photo spots. Rendo Park for the past dozen years has not been noticed so that it looks neglected and is not used by the public for recreational purposes. This is because there is no representative playground for children, so the government feels the need to develop Rendo Park into a children's playground. In the design plan, Green Architecture is the right design solution for the planned object. The method used is an architectural design method with a Green Architecture approach as a design reference. The analysis used in this design are environmental analysis, actor analysis, spatial analysis, mass shape analysis, and outdoor space analysis. Green Architecture is the right design solution for the planned object. The result is a playground that uses architectural elements as design principles to be explored. The purpose of green architecture in the design of the playground is applied to three points, namely: Building, which is a climate-responsive building concept that is in accordance with the characteristics of green architecture from mass form, roof shape, material, and structure. Landscape is an energy-efficient garden concept and the use of recycle sclupture which becomes site furniture later. Circulation is through convenience and comfort

Analysis of wind loads in the building with a variation of roof shapes

The Indonesian’s geographical position, which makes Indonesia frequent disasters due to wind, objects unable to withstand the wind can lift or shift these objects. This condition causes damage, such as a roof that is raised or floating. Buildings in Indonesia generally use gable roofs, hip roofs, and one-sided sloping (shed) roofs, while several types of roofs can be used in buildings, such as mansard roofs and curved roofs. This study uses a quantitative approach, which records and analyzes research data and performs data calculations with statistical calculations. This research compares wind loads based on SNI 1727-2013 Minimum Load for Planning of Buildings and Other Structures with different roof shapes in Bandung to determine the effect of each roof shape on wind loads on buildings and obtain roof shapes. With the smallest and largest wind load influence. Based on the research results, the displacement value in the roof structure due to wind loads is 0.025118 m (Hip and Gable), 0.018352 m (One-sided Sloping z1), 0.036073 m (One-sided Sloping z2), 0.027238 m (Mansard), 0.017629 m (Curved). Buildings with curved roofs produce minor wind load effects, and buildings with one-sided sloping roofs have the most significant wind load effects.

Simulation of the roof shapes and building orientation on the energy performance of the buildings

Simulation of the roof shapes and building orientation on the energy performance of the buildings

Effects of roof configuration on natural ventilation for an isolated building

Numerical analyses based on CFD steady RANS were conducted to investigate the effects of roof configuration on wind-induced natural ventilation for an isolated roofed building. Gable roof and saltbox roof building models were tested with 15˚, 25˚, 35˚ and 45˚ roof pitch in present study. The flow field information and flow characteristics were obtained from the contours and plots generated by CFD. In accordance to the increment of roof pitch, the turbulence kinetic energy and mean velocity ratio show vigorous response. The flow separated at the windward corner do not reattach onto the roof, thus induced higher velocity gradient and form a large vortex at the roof ridge. The vortices behind then building caused by the flow separation at the roof ridge extend along the mixing layer and spread up to the roof. The pressure differences mainly rely on the roof shapes. Greater pressure differences between the upstream, interior and downstream was observed in saltbox roof cases. This is due to the extended roof height which boosted the impinging effect caused by the incoming wind. Generally, the saltbox roof configuration exhibit better performance than gable roof in terms of the measured parameters.

Electromagnetic energy in buildings: analysis of the effect of roof shape and treated materials

This paper introduces a scientific approach for the simulation and analysis of electromagnetic radiation (EMR) patterns indoors. It applies physics laws in analyzing EMR interaction within real-like 3-D buildings with plastered walls, illustrated by a visually scalable representation. The research objective is to investigate the effects of different roof shapes and some architectural parameters on EMR patterns in buildings using a CST simulator. The effects of new materials such as treated cement mixtures and sheets of Carbon Nanotubes composite materials are also examined. The shielding effectiveness within the zones of human activity of the model buildings are evaluated. The results identify the determinant parameters for EMR shielding and pinpoint potential locations for energy harvesting. The simulation results of the multi-layered wall are verified using MATLAB. Field measurements are performed on an actual building. The measurement results support the efficiency of the simulator in evaluating EMR levels indoors with an acceptable error.

Numerical simulation and experimental validation of solar greenhouse dryer using finite element analysis for different roof shapes

The word greenhouse dryer is used for a building which is highly glazed with thermal conditioning for desired range and it is used for cultivating crops, plants, vegetables, etc. The actual working of a greenhouse is that the short-wave radiations falling on the greenhouse are absorbed by the outer glazing material thereby heating the interior area of greenhouse and providing ambient heat for plants, vegetables growth respectively. The heated space is retained within the enclosure of greenhouse. This phenomenon is called as greenhouse effect. The important role played during the greenhouse effect phenomenon are atmosphere, insulating roofs, walls, etc. The current study focuses on the numerical and experimental validation of Solar Greenhouse which is utilized for drying phenomenon. The numerical simulation is performed using Finite Element Analysis method. The various roof shapes have been incorporated to have emphasis on maximum solar gain to drying phenomenon.