Pitched Roof Research Articles

Automated generation and semantic segmentation of roof orthophoto for digital twin -based monitoring of slated roofs

Roofs are one of the building elements most exposed to environment-induced deterioration, and their deterioration can rapidly result in potential safety hazards to occupants or even buildings’ failure. In pursuit of cost-effective, efficient and pro-active building roof monitoring, this paper presents a computing pipeline for: 1. Automated roof orthophoto generation that uses as input the 3D reconstruction from structure-from-motion photogrammetry and the building’s Digital Twin (DT) model, and outputs occlusion-free panel orthophotos with metric resolution. 2. Automated orthophoto semantic segmentation using deep learning to extract visible roof sub-components from the orthophotos. Various segmentation models are tested and contrasted. The approaches are validated with three real case studies of traditional buildings with slated pitched roofs. The proposed approach employs a generic pipeline which could be applied to any element of the building fabric.

Numerical analysis of thermal mechanism in downward flame spread over inverted surfaces of discrete inclined solid fuels

This investigation is propelled by engineering challenges associated with heat transfer during fire incidents on inclined surfaces, such as those observed in pitched roof fires, which hold significant implications for fire safety engineering and energy conservation. Drawing inspiration from real-world fire dynamics, this study delves into the downward flame spread over inverted solid fuel surfaces across a range of inclination angles, bridging the gap between theory and practice. Detailed analysis of temperature distribution, flame characteristics, and gas-phase reactions reveals critical insights into the complex interplay governing heat behavior under these conditions. The observed reduction in flame thickness and standoff distance with increasing inclination underscores the influence of buoyancy-induced plumes. This work developed a dimensionless formula that accounts for both buoyancy-induced plumes and diffusion rates perpendicular to the fuel, successfully capturing the variation in flame thickness with inclination angles. Furthermore, our findings show that the average flame spread rate escalates with higher inclination angles, attributed to enhanced gas-phase reactions near the flame front that lead to intensified heat transfer and a subsequent increase in temperature within the solid phase. The study also uncovers a competitive mechanism between flame “jumps” and heat transfer to the unburned zone, causing an initial increase and then a decrease in flame spread rates with increasing discrete gap size at larger inclination angles. Conversely, at smaller inclination angles, flame progression halts as the discrete gap size increases, due to inadequate heat transfer to the adjacent discrete fuel, resulting in the cessation of flame spread. This study not only advances our understanding of the thermal processes underpinning flame spread in inclined configurations but also offers crucial insights for developing more effective fire protection strategies and thermal protection systems in engineering applications.

Building-Integrated Photovoltaics in Existing Buildings: A Novel PV Roofing System

Among renewable energy generation technologies, photovoltaics has a pivotal role in reaching the EU’s decarbonization goals. In particular, building-integrated photovoltaic (BIPV) systems are attracting increasing interest since they are a fundamental element that allows buildings to abate their CO2 emissions while also performing functions typical of traditional building components, such as sealing against water. In such a context, since one of the main challenges to decarbonizing the building sector lies in the retrofitting of existing buildings, the current paper is focused on the design, development, and testing of a novel roofing BIPV system. The entire research was carried out as part of the Horizon 2020 HEART project. In more detail, the research analyzed the requirements of typical pitched tile roofs, which are currently the most common type in Europe, and developed a universal photovoltaic tile that can be easily and quickly integrated into such a type of roof. The research was also aimed at minimizing the embodied energy of the component and promoting disassembly and recycling at the end of life, fully in line with a circular economy perspective. The adopted design and development processes are described in detail in the present paper, along with the results of several tests performed in the field. In addition, further development prospects of the component, aimed at meeting the integration requirements in historic buildings, are finally presented.

Investigation of the integration of an oscillating aerofoil-based energy harvester into the building roof

The increasing energy efficiency requirements have led to innovative renewable energy solutions being integrated into buildings. Several works have shown the potential of micro wind turbines on buildings. However, their implementations have been hindered by several challenges. Flow energy harvesting devices such as oscillating aerofoils provide potential, yet a literature gap exists regarding their integration into buildings. This study addresses this gap by investigating oscillating aerofoil wind energy harvesting system performance through numerical modelling. A coupled numerical model was introduced, integrating a novel computational approach using ANSYS Fluent with one degree of freedom in rotational motion. This methodology was introduced to analyze the dynamic behaviour and predict mechanical power output of the oscillating aerofoil wind energy harvesting system, which is a novel exploration in existing literature. Moreover, validation of the computational fluid dynamics model was conducted through using experimental wind tunnel data in the literature, and results demonstrated agreement between numerical and experimental results. To improve the wind energy harvesting system of a single oscillating aerofoil, it was integrated into building roof to take advantage of acceleration effects of building roof shape. The design improvement comprises of a novel wind energy harvesting system design of an oscillating aerofoil integrated into three different building roof including flat, pitched, and curved shapes to enhance energy efficiency. The numerical analysis demonstrated that integrating an oscillating NACA 0012 aerofoil into a curved roof resulted in the highest average power output. Specifically, the integration of the curved roof and the aerofoil yielded 18 watts, while the flat roof generated only 0.6 watts at a wind speed of 3 m/s. Integration into a pitched roof achieved 12 watts at 9 m/s. Comparatively, integrating the curved roof with the aerofoil increased power output by 50% compared to the pitched roof design at 9 m/s wind speed. Thus, variations in wind speed significantly impact performance. In addition, changes in wind direction from 0 to 10 degrees led to reduced efficiency and lower predicted power output. Lastly, the power spectral density for NACA 0012 integrated into the pitched and curved roof buildings revealed peaks at 5.8 Hz in 9 m/s wind speed conditions.

Безопасность возведения эксплуатируемых кровельных покрытий с системами озеленения с использованием современных систем обеспечения безопасности работ на высоте

The relevance of the study relies on the fact that works at height are classified as highly dangerous. The number of injuries caused by falls from heights is threatening, compared with other factors of injuries. According to the statistics, the share of injuries caused by falls from heights is 28 %. According to the legislation, construction works are classified as works at height if there is a risk of fall for an employee from a height of 1.8 m and higher. At the same time, an employer must ensure the implementation of measures to minimize the existing level of injury rate at the construction site following the effective legislation. The basic measures of protection of employees working at heights can include personal and collective protection equipment and the use of protective fencing. In addition, the measures of protection include stationary anchoring devices mounted on the roofs of buildings. There are several versions of construction of anchoring lines; e.g., for concrete, metal, or green roofs. The structure of the anchoring device changes depending on the type of roof; e.g., a flexible anchoring line can be used in locations where the architectural appearance of the building must be preserved; due to its low visibility it is used for pitched roofs. A rigid line is more visible, and it is more appropriate to use it in locations where its impact on the architectural appearance of the building will be minimized. According to the conducted analysis, the existing safety systems used for roof works, to a certain extent, depend on the greening systems of the roof in use.

A Proposal to Revive the Brewster Wheeler Recreation Center: An Architectural Approach

This research dives into the historical roots and proposed revitalization of the Brewster Wheeler Recreation Center, located in downtown Detroit with a focus on the city's progress and the preservation of its heritage. Almost all previous renovation plans for the city of Detroit have come to a halt due to the lasting effects of COVID-19. However, as the pandemic has come to an end, Detroit has been making huge leaps in its revitalization efforts. The paper’s main objective is to contribute to the city of Detroit and have applications to the real world. The proposal presents a pitched roof design that shows remnants of the building’s historicalness and highlights its novelty, creating a balanced blend between the two. The proposal also takes advantage of the expansive surrounding land to position the recreation center as a central community hub by including sports fields and a historical museum inside the building. The museum would serve as the history of the building’s evolution and notable figures from its humble beginnings as a library in 1917 to its present state.

РАЦИОНАЛЬНЫЕ КОНСТРУКТИВНЫЕ РЕШЕНИЯ КРУГЛОГОДИЧНЫХ АНГАРНЫХ ТЕПЛИЦ

The subject of the study is year–round greenhouses of the hangar type for individual and farm farms. The costs of the construction and operation of greenhouses significantly affect the cost of agricultural products grown in them. Optimization of the design solutions of hangar greenhouses is important to reduce internal forces in the frame elements, reduce the material consumption and cost of greenhouses. The purpose of the study is to determine the optimal design solution for hangar greenhouses up to 6 m wide. The study was conducted with the help of the Russian certified software package "Lira-CAD". Calculated models of hangar greenhouses with arched, gable-roofed and lancet-shaped greenhouses with a width of 3 to 6 m have been developed. The design solutions of the greenhouses were developed taking into account the requirements of the code of rules SP 107.13330 "Greenhouses and greenhouses", based on the possibility of using polycarbonate sheets in enclosing structures. Comparative calculations of greenhouse structures in the Lira-CAD software package have been performed. The calculation results are analyzed. Conclusions have been drawn on optimizing the design solutions of hangar greenhouses up to 6 m wide. The study showed that among the considered types of greenhouses, the most rational in terms of metal consumption are lancet-shaped greenhouses. The specific consumption of metal in lancet greenhouses is 42..53% lower than in greenhouses with an arched roof, and 34...64% lower compared to greenhouses with a pitched roof. The specific consumption of metal decreases with an increase in the width of greenhouses, the greatest decrease in the specific consumption of metal is observed in greenhouses with a pitched roof. The most technologically advanced from the point of view of manufacturing and installation are greenhouses with a pitched roof, the manufacture of the frame of such greenhouses from galvanized steel pipes is possible in building conditions, and both polycarbonate and glass can be used for translucent fences.

A pitched roof-like hybrid piezo/triboelectric nanogenerator with reliable supply capability for building a self-powered industrial monitoring system

As a result of increasingly stringent power supply requirements and diverse application scenarios, the development of hybrid nanogenerators that can combine multiple power generation modes has gradually become a hot research topic. In this work, the PR-HNG, a piezo/triboelectric hybrid nanogenerator based on a pitched roof structure, is proposed and is used efficiently to perform discrete mechanical energy harvesting. Using the flexible connection of its separated roof-like trigger mechanism, the PR-HNG operates through inertia under vibration conditions and achieves a satisfactory working state with very low mechanical loss. At 10 Hz, the instantaneous open-circuit voltage VOC and short-circuit current ISC of the PR-HNG can reach 800 V and 9.6 mA (1.60 A/m2), respectively, and no obvious attenuation occurs during high-intensity and long-term operation. After connection to a load via a rectifier bridge, the PR-HNG has a maximum power output of 575 μW/cm2 and can charge a 2 mF capacitor up to more than 2.5 V in only 30 s; these two performance parameters are better than the reported values for other similar types of HNG. In practical applications, this PR-HNG can easily drive more than 1440 commercial light-emitting diodes and can drive small electronic devices in real time. Therefore, the PR-HNG has been demonstrated to provide a credible and promising solution for fabrication of self-powered monitoring systems for use in industrial environments.

A Review on the Roofs’ Design Influencing the Physical Environment in the Naturally Ventilated of Mosque Buildings

The modern pitch and domed roofs design of the Malaysian mosques was created as a symbolic of Muslim place of worship besides functioning as a filter to the outdoor climate. Malaysia is a country that is famous for the high air temperature and relative humidity and inconsistent air movement of local climate which can influence the indoor environment. The different roof designs of Malaysian mosques also give impact to the believers in conducting prayers and other activities inside the mosques. Therefore, this study is to investigate the difference of roof design that influenced the thermal comfort and believers’ convenience in the mosque's building. It was found that the traditional roof design of mosques in Malaysia was the pitched roof with two and three-stacked mosques whereas most of the modern roof design was the domed roof. Both the pitched and domed roof of the mosque's design had the ability to control the indoor air distribution inside the mosque building. The pitch roof had the ability to control the circulation of the indoor air movement to achieve the equilibrium state whereas the domed roof could stratify the outdoor cool air to replace the hot indoor air inside the mosque building. Therefore, the future researcher could focus more strategies in order to improve the roof design of mosque for better indoor air inside the mosque building.

A French Residential Retrofit toward Achieving Net-Zero Energy Target in a Mediterranean Climate

Cities are paying more attention to building energy use and carbon footprint for attaining sustainability. Within this building sector, there is a growing attention toward development and adoption of energy efficient retrofit strategies. Plagued by the lack of efforts in achieving comprehensive energy efficient retrofit solution sets (passive, active, and renewable energy systems), the authors acknowledge the concept of NZEB toward achieving energy efficiency by 2050. Toward this end, a numerical energy simulation modeling is carried out to retrofit an existing French “Puccini house” using ‘passive, energy efficient building systems and renewable energy’ strategies toward an NZEB target in the Mediterranean climate of Nice. Using Design builder 7.0, the simulated baseline energy model (Case A) is retrofitted through variations in the proposed energy efficient retrofit measures using two case scenarios (Case B: passive retrofit; Case C: energy-efficient building) to achieve NZEB (Case D). Assessing the performance of energy efficient retrofits using % energy reduction, the implementation of a high-performance building envelope is achieved using a thermally insulated external wall (46.82%), upgraded airtightness (20.39%), thermally insulated pitched roof component (33.03%), and high-performance window type—a glazing system (3.35%) with maximized window-to-wall ratio (5.53%). The maximum energy-saving retrofit solutions provide an ambitious reduction in energy consumption by approximately 90% from the baseline. A deep retrofitting of the French house meets the NZEB targets, as it reduces the baseline energy consumption from 194.37 kWh/m2/year to 23.98 kWh/m2/year using both passive and active strategies. The remaining energy demand is met by the integration of on-site PV panels (EUI= −27.71 kWh/m2/year), which achieve an increase in energy production by 15.5%, while returning energy back to the grid (−3.73 kWh/m2/year). Findings of this study serve as a guideline for retrofitting traditional French single-family residences, while contributing toward the NZEB goal.

Fluid Flow and Heat Transfer Characteristics of Clerestory-Shaped Attics Heated from Below

In this study, a finite volume analysis of the aerodynamics and heat transfer in attics of a clerestory roof design with pitch angles 14o, 18o, 30o and 45o and Rayleigh number range 3 x 105≤ Ra ≤ 2 x 107 is carried out. The shape of the enclosure has strong influence on the structure of the flow and temperature fields. The flow field is characterised by counter-rotating vortices enclosed by aerodynamic boundary layers. The size, strength and direction of rotation of the cells are controlled by the forces propelling the thermal plumes and the cold jets. The reduction of the number and size of the counter-rotating cells and their formation within the enclosures provide an analogous reduction of the total heat transfer rate as the roof pitch angle increases. The velocity and temperature profiles across midheight and midlength of the enclosures enable the prediction of appropriate position in the attic with the right condition to place sensitive items. On the heat transfer, the relationship between the mean Nusselt number and the Rayleigh number is presented in form of a correlation. Results obtained in the study are of significance to building engineers engaged in the analysis and design of building attics and tropical agriculturalists for the control of produce drying rates. Keywords: Heat transfer, heated below, natural convection, pitch roof, clerestory-shaped

Neighborhood, Topography, and Wind Direction Effects on Wind Pressure Distribution on the Low-rise Building Roof

Low-rise buildings are the majority of the houses that are constructed all over the world. Experiments of the wind loads acting on these buildings provide vital information to design secure structures and adverse weather conditions resistants, considering the basic parameters as roof slopes and the wind direction. This study estimated the distribution of wind pressures around the contour of buildings with gable roofs, considering diverse neighborhood conditions, namely the number and geometric configuration of buildings on the ground, in conjunction with the different angles of wind incidence and topography. The simulations took place with Ansys Workbench software, and the RNG K-Epsilon turbulence model and tetrahedral mesh were employed. The application validation of the CFD technique occurred in the double-sloped pitched roof structure. The results showed good concordance with the literature. The pressure coefficients were analyzed, as well, in the flow visualization, highlighting the attachment points and the recirculation zones.

Experimental and numerical simulations of air quality in an urban canopy: Effects of roof shapes and atmospheric stability

The roof shapes of buildings and atmospheric stability play vital roles in dispersing and transporting pollutants in urban canopies. This study investigated the influence of roof shapes and atmospheric stability through experimental and numerical simulations. Wind flow and gas diffusion simulations were conducted around buildings in urban canopies using wind tunnel experiments and computational fluid dynamic models based on Reynolds-averaged Navier–Stokes models. Four building roof shapes and three atmospheric stability conditions were used in this study. The results of the experiment and numerical simulations were validated using quantitative computational models based on the validation metrics. The numerical simulation results corresponded with the experimental results for the flow and dispersion. The simulation results showed that the flow velocity of the slanted roof was higher than that of the other roof shapes. The pollutants accumulated near the slanted and pitched roofs' leeward side were higher than those in the flat and hip-shaped roofs. Pollutants in the building increased under stable atmospheric conditions and decreased under unstable atmospheric conditions.

Overheating in the Attic Space Classroom in Summer

Abstract The presented study deals with the space located in the attic of an older building after reconstruction. Originally, the attic space was not used, as it did not have sufficient headroom. The reconstruction was designed in such a way that the entire original pitched roof was gradually raised by 1.2 meters in parts, creating a full-fledged space under the pitched pitched roof. The visual connection of the interior space with the exterior was ensured by continuous strips of vertical windows around the perimeter of the building, each window measuring 600x600 mm. The space is also illuminated by several skylights at roof level, which, although they ensure sufficient penetration of daylight from above into the interior, at the same time allow for considerably unpleasant overheating. The task was to find a way to optimize the size of transparent surfaces and determine the accumulation of building structures in order to achieve an acceptable cumulative effect of daylight and overheating, i.e., permissible increase in indoor air temperature in summer. It means trying to theoretically design a suitable and comfortable interior space in the attic in an already existing building.

Using forensic reports to manage the probability of lawsuits being filed in relation to pitched roofs: the case of Madrid

Roofs are among the construction units in buildings with the highest number of deficiencies and problems. Given their direct and constant exposure to weather (temperature, wind, rain, snow…), even minor issues can lead to important pathology processes if not addressed early on. This research examines unresolved issues of pitched roofs in the capital of Spain which eventually led to the filing of lawsuits. Different types of deficiencies were detected (humidities, condensations, fissures…) and classified according to their recurrence. The thousands of pages of forensic reports presented to the courts were consulted and analysed to determine the probability/risk of recurrence, based on a number of factors. Among them is the causal origin (according to the properties/characteristics of the materials or to the placement/application conditions) and the respective building typologies (single-family houses or multi-storey buildings). The results that were obtained were calculated through weighted risk matrices of the existing interrelations, before determining the levels of joint severity and the classification categories according to the final operational value.

COMPARATIVE THERMAL PERFORMANCE ANALYSIS OF ROOFTOPS WITH ELEVATED CEILING CONFIGURATION

In this study, thermal performance of different pitched roofs with elevated ceiling configuration is analyzed and compared. Three different ceiling shapes, viz., cathedral, barrel-vault and A-frame, at the same pitch angle and ceiling material, under winter heating are examined numerically by solving the steady-state air and heat flow problems simultaneously. In all the roofs, the airflow fields show counter-rotating recirculating cells. The multicellular flow field promotes uniform temperature distribution within the enclosures. Heat loss to the attic from the space below increases with the closeness of the hot ceiling to the cold inclined walls. In the A-frame roof, there is uniform convective heat transfer. But in the cathedral and barrel-vault roofs, near the bottom corners, conductive heat exchange predominates. In all, the thermal performance of the barrel-vault is least while that of the cathedral is best. This observation is useful on the application of insulation when using such ceiling shapes.

Reassessment of the potential for centralized and distributed photovoltaic power generation in China: On a prefecture-level city scale

The successful development of solar energy primarily depends on the scientific and effective evaluation of the photovoltaic power generation potential. This study re-estimated the installed potential of centralized large-scale and distributed small-scale photovoltaic power stations in 449 prefecture-level cities in China based on a geographic information system and Google Earth Engine combined with Baidu map data and related geographic information data. The factors considered in selecting the areas suitable for photovoltaic power generation were economy, terrain, environment for the centralized stations; illumination time, roof type, and shadow obstacles of the building for distributed systems. The results showed that a total area of 583 thousand km2 in China can be utilized to install solar panels, with a technical potential of approximately 55.1 TW. In particular, the technical potential of the centralized power stations was approximately 42.8 TW, primarily distributed in Naqu, Tibet and Haixi, Qinghai. The potential of the distributed systems was approximately 12.3 TW (including 4.9 TW for flat roof, 3.5 TW for pitched roof, and 3.9 TW for building facade), primarily concentrated in Yulin and Guigang, Guangxi; and Meizhou, Guangdong. The findings can clarify the spatio-temporal distribution of photovoltaic potential nationwide and provide decision support for regional planning.

Simulation of solar thermal panel systems with nanofluid flow and PCM for energy consumption management of buildings

The present study simulates a solar thermal panel using the finite element method (FEM) in COMSOL Multiphysics. A cropper pipe of a water-Al2O3 nanofluid flow was used under a solar panel. A number of elliptic fins were attached to the pipe. The fins were holed and configured in three models. The system of the pipe and fins was placed in a chamber filled with CaCl2.6H2O as a phase change material (PCM) under the panel. The proposed solar system was used on a pitched roof to partially supply the energy demand of the Boarding clinic. The energy calculations were carried out in Design Builder. It was found that PCM began to melt at t=40 min. The fins with a central hole led to 10.4% higher melted PCM than double-hole fins at t=100 min. The centrally-holed fins minimized the output flow temperature. However, they also minimized the PVT temperature. It was also found that the proposed system could supply 9.11% of the heating demand of the building in the coldest month of the year. In hot months, however, up to 33.3% of the energy required to heat water could be supplied by the PVT + PCM system.

Thermal comfort optimization through bioclimatic design in Mediterranean cities.

Background: Bioclimatic design is an approach based on local climate which improves thermal qualities and indoor comfort. Buildings follow this process to minimize negative effects on the environment. However, this approach is still not suitable in developed countries. This study aims to investigate Mediterranean local bioclimatic strategies' impact on thermal comfort efficiency in housing, by examining architectural elements and treatments. Methods: We adopted a descriptive, analytical, and comparative methodology, complemented with a software simulation, within a qualitative and quantitative approach. Investigation and methodological tools were based on technical information including plans, elevations, photos, and documentation. The approach consisted of multiple stages: a literature review interpreting the concept of bioclimatic design, as well as thermal comfort variables and common Mediterranean building features. Moreover, the paper showcases three examples of successful Mediterranean passive houses. Furthermore, the paper presents a case- studyhouse in Alex West, Alexandria, designed in the Mediterranean Revival style. Results: The results showed that the most influencing building features on thermal comfort were the low-pitched roofs and the top chimney, which achieved 12.6% and 5% improvement in the summer and 13% and 6.8% in winter, respectively. The pergola and porch elements barely had an effect when placed on the northern façade. However, on the southern façade, a positive contribution in the summer by 1.4% and 3.4% respectively were reported, but a slight negative impact in winter by 0.5% and 2% respectively. Conclusions : We examined the impact of common Mediterranean building features , and compared thermal comfort results between case-study houses. Features focusing on passive design for cooling rather than heating, allowing wind flow for maximized natural ventilation, using ventilated pitched roof spaces, using sun shading elements in the proper facades and angles, help passive thermal regulation. The study proposes recommendations for optimizing thermal comfort in residential buildings in Alexandria, Egypt.

Improving the Air Permeability of Ventilated Roofs

In hot climates, ventilated pitched roofs help dissipating the excess heat, thus reducing the cooling energy demand. The key factor is the so-called Above Sheathing Ventilation (ASV) that depends on the air entering and leaving at the eaves, ridge and the gaps among tiles. A strategy for increasing the ASV is the enhancement of the roof air permeability through the development of new tile shapes, as proposed in the European Life HEROTILE project. The performance of a ventilated pitched roof are experimentally analysed by comparing some covering options: the new tile shape designs against the standard ones, available in the market, and a metal cover. A real scale pitched roof mock-up was built and equipped with a comprehensive monitoring system. The air flow and temperature in the different roof layers, as well as the heat flux passing through the roof and the cooling energy demand, were monitored according to the local weather conditions during the summer season. The analysis showed that the new tile design increases the ASV in comparison with the standard ones, and better thermal performance was achieved by reducing the heat gain due to solar radiation.