Roof Of Building Research Articles

Energy Efficient Features of Vernacular Houses in Tropical Hilly Area of Indonesia

Energy efficient building is one of the alternative solutions to overcome the rapidly increasing use of energy consumption by the building sector. Traditional or vernacular houses rarely use mechanical means to create a comfortable living environment. Thus, the electrical energy consumed by traditional or vernacular houses was relatively low. It is believed that energy efficient features can be found in vernacular houses. Thence, this study explores the energy efficient features of vernacular houses, with a case study in the hilly area of the tropics, Palu-Indonesia. Field studies were conducted. Six vernacular houses were chosen purposively as the study samples based on building orientation, building form, roof form, wall construction, and type of opening. HOBO H21 and U12-012 were utilised to measure the internal and external air temperature, relative humidity, light intensity, wind speed and wind direction. The study result indicates that the sample houses’ thermal condition was slightly better than the external thermal condition. Sample 1 can modify the external air temperature up to 42.8 K during the daytime. The light condition, in contrast, showed poor performance. Thus, more transparent material with proper shading was needed to succeed daylighting in the buildings’ interior. Several energy efficient features of vernacular houses found in the samples are as follows: shallow building plan elongated to East – West, building geometry, resistive building materials, the use of ceilings, and side-hung or jalousie type of windows with an adequate size of the effective opening for ventilation and lighting.

Напряженно-деформированное состояние трехгранной фермы с неразрезными поясами пятигранного составного профиля

Introduction. The author considers designs of triangular trusses that can be used to design roofs of industrial and public buildings, various combined systems, and also as overpass structures of linear facilities. The design of a spatial truss as part of a patent pending development of a triangular truss cover with non-cutting closed-section chords is presented. The purpose of numerical studies is to estimate the stress-strain state (SSS) of a spanning triangular truss subjected to static nodal load and different arrangement of strut elements as well as to create a verification database for further numerical studies of non-faceted interface nodes. Materials and methods. The numerical research methodology takes into account the application of nodal static loads, modelling the placement of the enclosing structure of the pavement using purlins. The use of the unit load method is aimed at determining the response of the load-bearing system as part of a comparative evaluation and comparison with the data obtained from other research tasks. Results. In the course of numerical studies, data were obtained, characterising the deflected mode of the triangular truss model in terms of force distribution in the rods and vertical displacements of the nodes. Conclusions. Analysis of the obtained results shows that the accepted design model of a triangular truss adequately reflects its deflected mode. Practical application of the numerical research technique on the basis of application of unit nodal loads consists in the possibility of using calculation results in the form of a structured data set required in calculations by the limit states method. The results obtained can be used as a basis for verification of data obtained in further numerical studies of non-faceted node constructions within the framework of the lamellar mathematical model. The presented numerical studies are part of the complex of scientific research into the actual performance of spanning triangular trusses.

Effect of System Reliability on Design of Metal Building Roof Purlins

This paper provides a framework to incorporate structural system reliability effects in the design of roof purlins in a typical metal building. Today, every roof purlin is considered as a separate component, and the effect of spatial variation in the demand loads and potential redistribution and load sharing in the roof system capacity is ignored in design. Component reliability is established by first-order reliability methods implemented through load and resistance factor design. Based on recent work in load-bearing cold-formed steel framing systems, the load and resistance factor design framework is extended from components to systems through an additional resistance factor to account for system influence. An archetypical metal building is designed and selected for this study. Monte Carlo simulations of a segment of the metal building roof are performed with consideration of both randomness in the demands and capacity and employing geometric and material nonlinearity in the response model of the roof. The simulations indicate that the system effect in metal building roofs is beneficial, and increases in the design capacity when evaluated against demands may be justified. Sensitivity to the target reliability (allowed probability of failure), deflection limits, and modeling assumptions are observed and discussed. Preliminary factors to account for roof system reliability are provided.

Scaling method between sub-scale helium and full-scale smoke tests of smoke spread during solar roof fires

Increasing numbers of photovoltaic or solar panels have been installed on building roofs worldwide. Meanwhile, fires from solar roofs were also reported to increase when they are overheated. During a solar roof fire driven by wind and thermal buoyancy effects, the toxic smoke can spread around and infiltrate back into the building and creates major concerns over occupants’ health and safety. To understand this complex heat and mass transfer process, it is possible to conduct full-scale fire studies, which are often constrained by the cost, so the associated studies have been found inadequate in the literature. In comparison, a sub-scale experiment in a wind tunnel can be a cost-effective method for understanding the mechanism of the smoke spread from solar roof fires. However, this may require a fireproof wind tunnel, and the use of actual fires in a lab context often creates safety and cost concerns and is thus impractical. Therefore, this study proposes a scaling method for conducting sub-scale wind tunnel tests with helium to generate a similar thermal plume and smoke spread behavior as an actual fire. The method was demonstrated by comparing the similarity of a 1/15 scale helium experiment in a wind tunnel and a full-scale smoke test by computational fluid dynamics (CFD) simulations using a fire dynamics simulator (FDS). A good agreement was found with an average difference of 7.02% for dimensionless velocity and 7.87% for dimensionless temperature. The difference among all cases was less than the maximum of 21.66%, which occurred only in the transient 45° roof scenario near the free stream region close to the indoor space. Therefore, the proposed scaling method of the wind tunnel helium test is justified in this paper when studying the smoke spread during solar roof fires.

Пространственно-технологическая структура отдельных технологических процессов при ремонте фасада и кровли

Today a regional program of capital repairs of common property in apartment buildings is being implemented, which is accompanied by the need to find new ways and technologies for performing work at the lowest cost, identifying reserves and parameters that have a direct impact on improving the efficiency of the manufacturability of the repair of common property of apartment buildings. The article discusses these solutions to improve efficiency based on the method of constructing the spatial and technological structure of individual technological processes consisting of several operations on the example of the repair of facades and roofs of an apartment building.

Pragmatic analysis of solar photovoltaic system design in an institutional building in eastern India

PV systems connected to the grid are primarily designed to generate clean energy to fulfil the rising energy demand. To predict the performance and efficacy of PV systems, several installation aspects are employed, such as location, local meteorological data, orientation, optimal tilt angle, varying losses, and energy yield estimation. Siksha ‘O’ Anusandhan Deemed to be University, Bhubaneswar (Latitude 20.24°N and Longitude 80.85°E) has taken one such initiative by installing a 13 kWp rooftop grid-connected solar photovoltaic system in one of its institutional buildings. The solar PV system is fixed at an angle of 21° and is installed on the rooftop of a 25-m height building. The measured performance characteristics were analysed and compared to those of PVSyst software to determine its feasibility in campus buildings. From the result, the annual electricity supplied to the grid is 17.79 MWh, final yield of 3.80 h/d, reference yield of 4.62 h/d and performance ratio of 0.82. The solar PV system installed at the institution is predicted to have reduced 17443.02 kg of CO2, 22.07 kg of SO2, and 46.1 kg of NOx from the atmosphere per year. The lebelised cost of energy (LCOE) of the installed PV system is 9.408 INR/kWh with a payback of 9.8 years. This study provides the techno-economic feasibility of installing grid-connected solar PV systems on the roof of an institutional building and help the solar installers in establishing the most efficient solar photovoltaic system’s sizing and design.

Optimizing the exchange of active power of the main and distribution network, which includes hydrogen energy accumulators, taking into account the price indicators

The paper considers the task of creating an instrumental system for optimizing the exchange of active power of the trunk and distribution networks, taking into account the price indicators of electricity in a joint and separate mode of operation. As part of the development of a simulation model of the automated control system of the local intelligent power system MicroGrid, the results of modeling the exchange of active power of the power connection from the main network of the main South of Russia main electrical networks and the distribution network of the university campus (in which classical sources of generation are combined with solar, wind and hydrogen energy) are presented.In a single model, the electrical mode of operation of networks is simulated in the voltage range of 0.4–500 kV. Simulation is carried out in steady state and transient mode. Slow, real and fast time modes are available. Simulation of emergency control systems has been implemented. The modes of synchronization of the main and distribution networks in normal and emergency circuits are considered. Reliability control and monitoring of the main operating parameters are carried out.The active power exchange module created on the basis of the results of the simulation as part of the software package « RETREN » will make it possible to use this complex to automate the management of local power system. The energy system, in addition to power from the grid, includes gas generation, solar panels installed on the roofs of campus buildings, wind turbines and stationary hydrogen power plants operating on hydrogen fuel cells. The complex of designers allows organizing human-machine interfaces of any complexity on completely domestic software products.

Optimizing PCM Integrated Wall and Roof for Energy Saving in Building under Various Climatic Conditions of Mediterranean Region

Energy conservation in buildings has been the focus of many studies since nearly one-third of global energy consumption is due to buildings. Phase change material (PCM) technology promises to be an attractive solution for energy saving in buildings since it is a passive and effective technology, as demonstrated in the literature. Therefore, this study focuses on the energy-saving performance of PCM-integrated buildings located in a Mediterranean climate to reveal their energy-saving potential. PCM is integrated both in external or internal south walls and roofs of buildings under four different climatic conditions. EnergyPlus, which is a well-known building simulation software, is adopted for building thermal analyses. The effects of melting temperature, location of PCM layer in the wall, thickness of PCM layer, type of envelope (wall or roof), and PCM double-layer system in the wall are investigated. The corresponding energy savings and CO2 emission reductions are obtained for the considered cases. The results showed that up to 41.6% reduction in energy demand can be obtained depending on the PCM application. Besides, PCM with a low melting temperature (21 °C) favored heating energy savings, while PCM with a high melting temperature (29 °C) favored cooling energy savings. Moreover, the double-layer PCM system provided higher energy savings than the single-layer PCM system, especially in warm and arid regions (Sousse and Tozeur).

Long-lasting self-cleaning daytime radiative cooling paint for building

Endowing the building exterior wall with superhydrophobicity and radiation cooling function can not only achieve building energy conservation, but also significantly reduce the cost of manual cleaning, so as to ensure the efficiency and durability of the radiant cooling function of the building exterior wall. However, it is still a challenging work to make coatings (paint films) with the above two functions on the surface of large external walls. Herein, we have developed a polyvinylidene fluoride/polydimethylsiloxane (PVDF/PDMS) composite coating composed of PVDF particles and PDMS binder, which is prepared by one-step brushing method. It exhibits solar reflectivity of 90.6%, infrared emissivity of 98.1%, contact angle of 158.2° and rolling angle of 7.9°. The PVDF/PDMS coating exhibits a radiative cooling temperature of 4.93 °C under direct solar irradiation. Importantly, both the DRC function and the superhydrophobicity of the PVDF/PDMS film exhibit excellent weatherability during the one-year outdoor weather resistance test and remarkable mechanical durability in sandpaper abrasion and sand impact tests. Therefore, the long-term self-cleaning DRC paint developed in this work has a potential application prospect in the field of building exterior wall or roof.

Beyond the Screen: Joan Jonas’s Television by Other Means

‘The resistance of distances having finally ceased, the world’s expanse will lay down its arms, once known as duration, extension, and horizon.’– Paul Virilio1 ‘The resistance of distances having finally ceased, the world’s expanse will lay down its arms, once known as duration, extension, and horizon.’ – Paul Virilio1 In the spring of 1972, a unique televisual event took place in downtown Manhattan. It was the year that the Watergate scandal broke; the first reality television show, ‘An American Family’, was in postproduction; and ‘The Price Is Right’ first aired on CBS. It was the season of the Easter Offensive in Vietnam, and the television sets that had for five years ‘brought the war home’ continued to transmit the distant conflict into American living rooms. Unlike these televisual spectacles, the event that took place on New York’s Lower West Side was not actually televised. Rather than sitting in front of the TV set and tuning in, the viewer would instead find herself climbing to the roof of a five-story building on Greenwich Street and looking out from this elevated position (Fig. 1).

Temperature-Responsive Double-Network Cooling Hydrogels

Skin inflammation can occur due to the immune response of the body, infections, and injuries and lead to an increase of skin temperature. Cooling inflamed skin can relieve pain and efficiently dissipate heat. Evaporative cooling hydrogels are hence promising materials for preparing flexible dressings for cooling inflamed skin because of the high latent heat of water vaporization (∼2450 J·g–1 at 100 °C and 1 atm). We fabricate here a double-network hydrogel formed with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) and poly(N-isopropylacrylamide) (PNIPAM). Water can be released by the PNIPAM network above ∼32 °C, which is close to human’s skin temperature, and provides heat dissipation and cooling through evaporation. The network formed with PAMPS delays the release of water from the hydrogels. Large and prolonged cooling performance of a skin model and enhanced mechanical properties are obtained with the proposed design. Compared to other reported hydrogels for passive cooling, our material demonstrates a superior cooling power with lower temperature. This design of the hydrogel can be adapted for cooling other structures such as photovoltaic panels or roofs of buildings.

:Architecture in Ancient Central Italy: Connections in Etruscan and Early Roman Building

:<i>Architecture in Ancient Central Italy: Connections in Etruscan and Early Roman Building</i>

Experiments and simulations on the energy performance of semi-transparent photovoltaic roof-integrated skylight glazing

Photovoltaic (PV) cells integrated with building roof skylights not only generate electricity but also influence the thermal performance of the roof. In this paper, the thermal mathematical model of a semi-transparent photovoltaic insulating glass unit (STPV-IGU) integrated with the roof is established and validated by experiments. Case studies are conducted by using the roof-integrated STPV-IGU in Shanghai, and an equivalent electrical method is used to evaluate the energy performance of roof-integrated skylight STPV-IGU. The equivalent electricity of heat-gain entering the room through STPV-IGU and total equivalent electricity of roof-integrated STPV-IGU is 16.6 kWh/m2 and 12.1 kWh/m2 in summer, respectively. The equivalent electricity of heat-gain entering the room through STPV-IGU and total equivalent electricity of roof-integrated STPV-IGU are −16.3 kWh/m2 and −4.0 kWh/m2 in winter, respectively. Compared with traditional insulating glass unit, the STPV-IGU can significantly reduce the heat-gains through glazing in summer, but increase indoor heat-loss in winter.

Contrasting determinants of land surface temperature in three megacities: Implications to cool tropical metropolitan regions

Megacities in tropical regions are among the urban centers most vulnerable to increasingly intense heatwaves. However, the complex interactions between urban characteristics and thermal environments are yet to be fully understood. Here, we investigated the relationship between urban characteristics and land surface temperature (LST) for three megacities in the tropical savannah climate zone, Chennai, Dhaka, and Kolkata. LST values were retrieved from Landsat 8 data, and urban features were constructed using digital surface models, building footprints, and satellite imagery. Model-agnostic approaches were adopted to analyze the impacts of urban characteristics on LST. The boosted regression tree (BRT) model was used to capture the nonlinear effects of six most important factors on LST changes. The dominant influencing factors of LST were normalized difference built-up index, albedo, and normalized difference vegetation index. Building roofs, roads, and other hardscapes with high-albedo materials are preferred in alleviating surface urban heat island effect in Dhaka and Kolkata. The placement of urban parks with woody vegetation in an area larger than 0.6 ha produced effective cooling effect. In Chennai and Kolkata, urban policies to increase sky view factor are recommended. The application of BRT model with integrated urban data provides unique insights for thermal resilience planning.

Determination of wind loads on porous sunshade roof cover sheets using conversion factor

Porous sunshade roof cover sheets installed on building roofs are new structures for mitigating heat absorption. Thus, there have been few studies on wind flow and its effects on wind-permeable structures, and there is no provision for these structures in the major international wind load standards and codes. Unlike wind loading on building roofs, wind loading on porous sunshade roof cover sheets is a combination of wind pressures on both the upper and lower surfaces, which complicates the calculation of wind loading. From the viewpoint of structural design, we need a simple method for determining wind loading on these structures. Wind tunnel tests have been carried out for various wind angles, three porosities (ratio between area of orifices and area of sheet), and five gaps between sheet and roof, and results have been analyzed. As a result, the author proposes a simple formula for calculating wind loading on porous sunshade roof cover sheets from wind loadings on normal building roofs available from wind loading codes and standards. The calculated results based on this formula and the Japanese wind loading standard (AIJ-RFLB (2015))[4] are compared with those of wind tunnel tests. There is a good similarity between them.

Novel lightweight Portland Pozzolana cement (PPC) stabilized mud composites using crumb rubber & agricultural waste: physico-mechanical and thermal performance

Mud is one of the oldest and most commonly used construction materials on the planet. Mud is used in building construction to provide shelter and as a heat-insulating medium, which is why mud is being used to cover the roofs of buildings in many hot climates. The goal of this experiment was to make Portland Pozzolana Cement (PPC) stabilized mud composites (masonry blocks: 400x200x200 mm and tiles: 300x300x25 mm) using less cohesive soil with the agricultural wastes. It was necessary to add binding material to the mix proportion for manufacturing composites out of earth materials because soil had very low plasticity. In this study, PPC (up to 10%) was used in the mix design along with optimized water binder (w/b) ratios. Each mix proportion was prepared by replacing and adding straw, crumb rubber, and bagasse with soil. In total, 15 different mix-proportions were made. The mix design for making such composites was created by targeting different properties, i.e., thermal conductivity (k)-value, dry density, and compressive strength. After casting, cubes were cured using two methods: water curing and moist curing. It was discovered that wet cured samples outperformed water cured ones. According to the trial results, a 7.5 percent mix proportion of crumb rubber and wheat straw in the soil and cement mix achieved the specified compressive strength of 5.86 MPa. Following that, two model dwellings (LxBxH = 430x510x330 ± 5 mm) were made in order to investigate the heat insulation properties of the composites. Finally, it was found that, with an average temperature differential of roughly 6 °C, the PPC-stabilized mud composite structure was found to be cooler than the typical model home.

The Effects of Roadside Buildings Roof Shapes and Tree Plantings on the Vehicle Exhaust Gas Pollution Dispersion in the Urban Street

In this study, the effects of roadside building roof shapes and roadside tree plantings on the dispersion of vehicle exhaust gas pollution in the urban street have been carefully explored. Three typical roof shapes, i.e., flat, triangle and round shapes, are considered in the present work. Firstly, the numerical simulations of air pollution transport in the atmospheric turbulent boundary layer with/without the vegetation canopy have been performed using Computational Fluid Dynamics (CFD). Secondly, the mean flow patterns and the distribution of turbulent kinetic energy (TKE) are then examined. Finally, the concentrations of the air pollution have been carefully explored. It is found that the triangle roof could result in a lower concentration of air pollution in the street canyon. The existence of the roadside trees could decrease the air pollution concentration, although its influence is much weaker than the roof shape. It is also found that the concentration of air pollution is quite related to the flow pattern and TKE distribution. This study could provide helpful guidance on the urban planners on the design of the urban street in the future.

Features of the seasonal dynamics of airborne fungal spore concentrations in Ukraine

Fungi represent a distinct kingdom of ubiquitous living beings. Most other organisms are constantly in contact with elements of the fungal body. In particular, the widespread vegetation of fungi in the environment, their sporulation and the further spread of spores and mycelia by air currents make the contact of fungal particles with human respiratory organs inevitable. This can lead to the development of sensitization and allergies. Therefore, the aim of the presented study was to determine the taxonomy of airborne fungal spores, the qualitative and quantitative changes in this composition at different times of the year compared with previous sporulation seasons, as well as the prevention of allergic diseases. The study of fungal sporulation was carried out from 2011 to 2021 by volumetric method using Burkard trap of a Hirst type in a 24-hour mode (from February to November). The device was installed on the roof of the chemical building of the National Pirogov Memorial Medical University, Vinnytsya. Reading of the microscopic slides obtained from air samples was carried out using light microscopes with a magnification of 400 and 1000 by the method of 12 vertical transects. It was found that spores of various taxonomic groups of fungi, namely, of Asco- and Basidiomycetes were observed throughout the growing season from March to October with the highest concentrations in mid and late summer. Thus, in June, July and August, peak concentrations of spores of the fungi Ganoderma, Coprinus, Cladosporium were observed; in July, September and October – of Ustilaginales; from July to November – of Alternaria, Epicoccum; in October – of different Basidiospores, and also Periconia, Stemphylium and Uredinales; in September – of Agrocybe. Among all studied micromycetes, concentrations of Cladosporium spores were the highest. However, significant sporulation persisted even in the autumn period, which made fungal spores a specific causative agent of airborne respiratory diseases at this time, especially against the background of low pollen concentrations. Climate change can lead to modification in the length of the fungal growing season. This information should be taken into account when predicting the symptoms of seasonal allergies in the population.

Wind Tunnel Experiments on Interference Effects of a High-Rise Building on the Surrounding Low-Rise Buildings in an Urban Block

High-rise buildings cause accelerated winds around them. However, the interference effects of high-rise buildings on the surrounding low-rise buildings in urban blocks have not been evaluated. This study investigated the wind pressure coefficients on the roofs and walls of low-rise buildings surrounding a high-rise building through wind tunnel experiments. Seventy-two wind directions were considered from 0° to 355° in 5° increments, and the influence of the wind direction on the wind pressure coefficients of surrounding buildings was evaluated. At a 30° wind direction angle, the positive and negative peak wind pressure coefficients occurred in a low-rise building at the leeward side of the high-rise building. The positive peak pressure, approximately 1.4 times that without a nearby high-rise building, occurred at the windward corner on the front wall of a low-rise building. The negative peak value, approximately three times that without a nearby high-rise building, was observed at the windward edge on the roof of a low-rise building. Thus, accelerated winds caused by high-rise buildings may result in unexpected damage to the surrounding low-rise buildings.

Vision-Based Detection of Low-Emission Sources in Suburban Areas Using Unmanned Aerial Vehicles.

The paper discusses the problem of detecting emission sources in a low buildings area using unmanned aerial vehicles. The problem was analyzed, and methods of solving it were presented. Various data acquisition scenarios and their impact on the feasibility of the task were analyzed. A method for detecting smoke objects over buildings using stationary video sequences acquired with a drone in hover with the camera in the nadir position is proposed. The method uses differential frame information from stabilized video sequences and the YOLOv7 classifier. A convolutional network classifier was used to detect the roofs of buildings, using a custom training set adapted to the type of data used. Such a solution, although quite effective, is not very practical for the end user, but it enables the automatic generation of a comprehensive training set for classifiers based on deep neural networks. The effectiveness of such a solution was tested for the latest version of the YOLOv7 classifier. The tests proved the effectiveness of the described method, both for single images and video sequences. In addition, the obtained classifier correctly recognizes objects for sequences that do not meet some of the initial assumptions, such as the angle of the camera capturing the image.