Roof-mounted photovoltaic generator temperatue modeling based on common brazil roofing materials

This paper examines the performance of solar photovoltaic generators on roofs of residential buildings. The primary focus is the loss of performance due to temperature increase as function of roof material and the distance from the photovoltaic (PV) generator to the roof. A heat transfer model has been developed to predict PV module temperature, and the equations of the model were solved using the Engineering Equation Solver (EES) software. The research modeling correlates the distance of the solar generator to the roof and the roofing material with the temperature variations in the PV generator. There are many models to predict PV module temperature, but this study refines the prediction by the distance from PV module to roof and the roofing material as variables. Optimal combinations of distance and materials that minimize the heating loss in the solar generator leading to increased electrical power generation. Results show an average error of 3%–4% from the temperature predicted by the model to the temperature measured under experimental conditions in Belo Horizonte, Brazil. The minimum roof-module separation required to ensure minimal PV performance loss from heating from the roof is ∼10 cm for red ceramic and cement fiber roofs. For galvanized steel, the optimal distance is between 20 cm and 30 cm. Cement fiber shows the best predicted and measured characteristics for PV-panel roof mounting among the 3-common commercial roofs evaluated in these studies. These investigations were based on roof installations and local materials in Belo Horizonte, Brazil.

Bryophyte species and communities on various roofing materials, Estonia

Considering the recent growth of interest in using mosses in creating vegetated green roofs, we set the aim of our study to get an overview of the variety of moss and liverwort species and communities growing spontaneously on roofs. Data were collected from 67 roofs of five different types of materials: fibre cement, bitumen, stone, thatched and steel from Tallinn and rural areas on Hiiumaa Island and in South Estonia. Indicator species analysis, MRPP, cluster analysis and ordination methods (DCA, CCA) were used for data analysis. As a result of this research, generalist bryophytes occurring on all types of roofing materials were studied and bryophyte species characteristics for certain material types were identified. The thatched roofs differed most clearly from the other roof types in their species composition and had the highest species diversity. Stone and fibre cement roofs had similar species composition. The results revealed significant dependence of the composition of the bryophyte flora on roofs on the density of the bryophyte carpet formed over time on the roof and the presence of a tree canopy above the roof. Other important factors were roof relief, the height of the roof from the ground and the indicator of environmental pollution NOx. However, the studied roofs in Tallinn and rural areas did not show significant differences in the species composition of bryophytes. Five communities were delimited: (1) Syntrichia ruralis – Schistidium apocarpum; (2) Orthotrichum speciosum – Bryum argenteum; (3) Brachythecium rutabulum – Hypnum cupressiforme; (4) Ceratodon purpureus – Rhytidiadelphus squarrosus; and (5) Pleurozium schreberi – Dicranum scoparium. The mentioned communities inhabited locations that differed in environmental conditions. The findings of this research can help choose the roofing material and species suitable for a certain location in creating moss greenery on 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.

Assessing Rainwater Harvesting Potential in Urban Areas: A Building Information Modelling (BIM) Approach

Water scarcity has become a major problem for many countries, resulting in declining water supply and creating a need to find alternative solutions. One potential solution is rainwater harvesting (RwH), which allows rainwater to be stored for human needs. This study develops an RwH assessment system through building information modeling (BIM). For this purpose, a hydrological study of Cfa-type climate cities is conducted with the example of Islamabad, Pakistan. The monthly rainfall data of three sites were assessed to determine the volume of the accumulated rainwater and its potential to meet human needs. The average number of people living in a house is taken as the household number. Household number or of the number of employees working at a small enterprise, roofing material, and rooftop area are used as the key parameters for pertinent assessment in the BIM. The data simulated by BIM highlight the RwH potential using five people per house as the occupancy and a 90 m2 rooftop area for residential buildings or small enterprises as parameters. The results show that the selected sites can collect as much as 8,190 L/yr of rainwater (48 L/person/day) to 103,300 L/yr of rainwater (56 L/person/day). This much water is enough to fulfill the daily demands of up to five people. Therefore, it is established that the study area has an RwH potential that is able to meet the expected demands. This study presents a baseline approach for RwH to address water scarcity issues for residential buildings and factories of the future.

Review of White Roofing Materials and Emerging Economies with Focus on Energy Performance Cost-Benefit, Maintenance, and Consumer Indifference

This article performed a comprehensive review of the different state-of-the-art of roofing technologies and roofing materials and their impact on the urban heat island (UHI) and energy consumption of buildings. The building roofs are the main sources of undesirable heat for buildings, especially in warm climates. This paper discusses the use and application of white roofing material in emerging economies. The use of white roofing material is a suggestion because of its cooling, evaporative and efficiency characteristics compared to traditional black roofing materials. Many research studies have shown that the darker roofing surfaces that are prevalent in many urban areas actually can increase temperature by 1 to 3 degrees Celsius to the environment surrounding these urban areas. Additionally, improved temperature control and heat reflection also work to reduce the energy requirements for the interior spaces of the structures that have white roofing surfaces. The white or lighter colored roofs tend to reflect a part of the solar radiation that strikes the roof’s surface. Consequently, one might believe that white roofing material would be commonplace and especially so within emerging economies. Yet, this is hardly the case at all. This paper examines the issue of white roofing materials in emerging economies from a dual perspective. The dual perspective includes the technical details of white roofing material and its impact on lowering the interior temperature of the affected structures, which consequently reduces hours of indoor thermal discomfort and use of air conditioners in indoor spaces. The other element in this study, however, involves the marketing aspect of white roofing material. This includes its adoption, acceptance and cost-benefit in emerging economies.

Organizational-and-technological solutions for installation of prefabricated roof coverings from roll materials

Implementing the modern technological methods is recommended in the article, as well as performing some operations. It should be considered that small and medium-sized enterprises involved in the construction of industrial and civil facilities are also installing the roof coverings. The algorithm of technological operations is as follows: preparatory work; gluing a two-layer waterproofing roofing on freshly formed reinforced concrete panels; double rolling of the uncooled roll roofing after removing the panel from the steam chamber. The process of installing the waterproofing roofing has to be carried out in a specially equipped enterprise area. It is recommended to use the following domestic and foreign tools and equipment for above-mentioned operations. Such equipment is a truck crane (for example, KS-45717), a roof crane (KL-3), a temporary fence, a metal ruler, a tape measure, roller or a brush, a scraper, a roofing knife and a roller (weight is 100 kg).The rational methods of roofing installation (based on labor intensity) are presented. As was substantiated, the calculation of labor can change while improving the technology and the tools and equipment used. The quality control of operations is described, it involves visual inspections and the necessary measurements performed with a ruler. Optimal organizational and technological solutions, which allow to manage processes taking into account the safety of workers, were obtained. Fulfilling the labor safety requirements during construction (part 1 and part 11) is primary while installing the roll-up waterproofing roofing made of melting roofing material with the help of a solvent. In addition, it should be noted that the workplaces and storage locations with flammable materials and substances have to be provided with a portable fire stand, as well as with fire extinguishing and medical equipment. The conclusions and recommendations on organizational and technological solutions forin stalling the prefabricated roofing from roll materials by using mechanization means are presented. They are intended for developers of organizational and technological documentation, including flow charts, work projects, regulations, codes of rules. They will be useful for students, masters, graduate students studying for professions related to the production of building, erection and special works.

Suitability of Wooden Shingles for Ventilated Roofs: An Evaluation of Ventilation Efficiency

Wooden shingles are a traditional roofing material on many culturally important building artifacts. Currently, the roof space of many traditional buildings is used for residential purposes and, consequently, cold roof constructions with ventilation layers are applied. In this study, it is evaluated whether the moisture content of wooden shingles is adversely affected by such constructions, compared with unvented shingle roofs over cold attics and whether a temporary closing of the ventilation gaps at the eaves contributes to a lower wood moisture content. Various sensors were installed in and around a building with wooden shingles on a ventilated roof and temperature, air moisture, and air speed in the ventilation layer were measured throughout a year. The findings show that the air speed in the ventilation layer can be adjusted from 0.06 to 0.25 m/s depending on the layout of the eaves. A hygrothermal model was applied to evaluate the effects of different ventilation operation modes and cardinal orientations of the roof on the moisture content of the wooden shingles. The results show that roof ventilation results in a 1% lower shingle moisture content on average than an unventilated roof over a cold attic. Finally, it is shown that the wood moisture content repeatedly reaches dangerous levels above 25% throughout a year, which is worse on north-facing roofs and, hence, measures to increase the dry-out are relevant.