Development of Psi Factors for Thermal Bypass Due to Insulation Gaps in Low-Slope Roofing Assemblies

In commercial roofs, the presence or formation of gaps could be due to improper installation, thermal expansion, and dimensional changes in the insulation boards. The heat loss from these gaps could lead to higher thermal transmittance in the roof assembly. The current research study conducted around 70 experiments to investigate the effect of gap height, gap width and gap offset on the thermal transmittance of the roofing assembly. The measured data showed that in a staggered insulation layout with a joint offset of 610 mm (24 in), formation of 6.4 mm (1/4 in) to 12.7 mm (1/2 in) gaps at the insulation joints could contribute to an average decrease of 2% to 9% in the effective R-value of the roof assembly. As the insulation thermal resistance increases or becomes thicker, the thermal losses in the roof assembly increase. Generalized gap impact curves were developed to provide the relation between gap parameters (i.e., gap widths and height) and the thermal performance of the roof assembly. The experimental data were further analyzed using the psi factor approach of linear thermal bridging generating thermal transmittance data to support the calculation of thermal bypass from gaps in the thermal roof design.

The native - exotic plant choice in green roof design: using a multicriteria decision framework to foster urban biodiversity

Green roofs are considered key elements of the urban green infrastructure since they offer several environmental benefits, including habitat provision for arthropods. To achieve these benefits and ensure green roof success, an appropriate plant selection is an important step in the design of these infrastructures, especially where green roof technology is emerging like in South American cities. So far, decisions of using native or exotic plant species in green roofs had never been evaluated taking into account the plant potential to foster beneficial arthropods. By applying an integrative multicriteria decision framework that combined the habitat template hypothesis with the potential of plants to attract floral visitors and natural enemies, we obtained a ranked set of candidate native and exotic plant species. Among the best-ranked candidate species, we further compared the performance of six native and six exotic species in 30 experimental green roofs installed in Cordoba city, Argentina. To evaluate plant success, the occurrence and cover of each species were recorded one year after establishment under two management conditions: regular watering and weeding of spontaneous plants, and no management (15 roofs each). All selected species increased their vegetative cover one year after establishment. More interestingly, native plants had an advantage over exotic plant species as they exhibited a significantly higher occurrence and a slightly higher cover with no management than exotics. Native annuals were able to reseed the following season even in the absence of management, thus highlighting the relative importance of lifespan as a useful plant trait for future studies in green roof design. Given that green roofs are one of the possible solutions to ameliorate the negative effects of urban habitat loss on arthropod diversity, the development of an integrative multicriteria decision framework that takes into account the potential of native and exotic plant species for promoting beneficial arthropods would give a new twist in plant selection processes for green roofs.

Helipad on the building roof design features

The following items are considered: requirements, constructive decisions for helipads; covering plate design of the helipad located on the building roof; helipad modeling in LIRA CAD SP; calculation of a multi-storey building with a helipad on the roof, check for strength and rigidity; characteristics of the helipad on the building roof.

Konstruksi Atap Rumah yang Tanggap Terhadap Pasir Vulkanik pada Kawasan Wisata Gunung Agung di Bali

<p class="Abstract"><em><span lang="EN-GB">The area around Mount Agung needs a roof design that can give extra protection for the residents. The volcanic sand may cause serious danger and damage to the residents' houses since it brings a heavy load to the roof. It causes roof collapses and it dangers the residents' safety. This study was a Research and Development Research and Development by Borg and Gall with a mixed method. Roof testing was done by carrying out an FGD by inviting one expert to provide input on the quality of the product, for revising and reporting the results according to the improvements. Based on the study, it was found (1) the needs of the residents due to the roof design, (2) the suitable type of roof that is resistant to the volcanic sand, and (3) the suitable roof construction for the residents around Mount Agung. The results of the study are expected to contribute to the construction design of residents' houses around Mount Agung that can protect them from the volcanic sand. </span></em></p>

A Conceptual Review of the Potential of Cool Roofs as an Effective Passive Solar Technique: Elaboration of Benefits and Drawbacks

Cool roofs, as feasible and efficient passive solar technique that reduces building energy requirements for cooling and improves indoor thermal comfort conditions, have received considerable attention in recent years and as a result, a number of concepts, methods, and experiences have been developed during the related research. Although some studies have been conducted on this subject in the form of review articles, taking into consideration the large number of publications, there is still a call for some review papers dealing with the potential of cool roofs and providing a thorough report on their energy performance and a detailed summary of their pros and cons on the basis of the relevant studies. On this account, this study contributes a systematic review of the issued paper in Scopus and Web of Science regarding the cool roof technologies to recognize the advantages and challenges of cool roofs in practice and its future trends. In addition, detailed summary of advantages and drawbacks of this passive solar measure has been developed, as itemized factors corresponded to the codified references. A total of 90 published reports were analyzed, declaring that a cool roof is an efficient approach for generating clean energy on the building scale. This article induces an overall view of the advantages and restrictions of the cool roof throughout the world. Conclusions give a valuable reference for improving the cool roof design for their more widespread use in the building industry.

Experimental Investigation of the Effects of Helical Roof on the Performance of Stairmand High Efficiency Cyclone

Cost-effectiveness of a standard and a modified Stairmand high-efficiency type cyclone was compared at various inlet gas velocities. The modified design was obtained by replacing the roof of the standard design with a helical roof. Experiments were conducted by both standard and helical roof designs at the same operating conditions. Results showed that helical roof leads to reduced pressure drop in cyclones while having a negative impact on particle collection efficiency. Reductions in pressure drop can reach up to 30%, while particle collection efficiency is reduced by up to 8% simultaneously. Overall, the treatment cost of a cyclone separator can be reduced by 14.1–20.8%. Results indicated that helical roof design cyclones can be used to reduce overall treatment cost by cyclone separators.

Investigation of snow load reduction in the industrial sheds roof design with photovoltaic systems by mathematical modelling, solar system evaluation, X-steel simulation and thermodynamic practices

Since snow load is one of the loads of designing the industrial shed roof, this research presents a new system to reduce the industrial sheds roof design. In this system, sensitive units of moisture and temperature, which can be adjusted with different areas, are installed on the shed’s roof. The mechanism of system is that the sensors in the units detect the presence of snow on the shed roof and send an order to connect electricity to the elements; therefore, the snow on the roof melts by the heat generated. In this system, solar panels are used to supply electricity. As with the help of this mechanism, snow does not remain on the roof, it is possible to eliminate the snow load in the calculations of the shed and apply at least the live load of the sixth regulation (Due to having a one-story shed, minimum live load applied and it used only for the foundation design of the structure.), this issue will create an economic plan in shed designing. According to the study conducted in this research, it is shown that the dimensions of the sheet beam used in the shed are reduced, which will significantly reduce the cost of construction and installation to some extent. In the following, two samples of sheds with a span of 20 meters in the presence of snow and the absence of snow in the software were modelled, and the results were compared with each other.

Justification of the use of square pipes in the frame of the removable roof of the open wagon

This paper reports determining the basic strength indicators for the removable roof of a railroad gondola. It has been established that the typical roof design has a significant margin of safety in the components of the supporting structure. In order to reduce the roof material intensity, the reserves of its strength have been determined and optimized based on the criterion for minimal material intensity. Pipes of square cross-section have been proposed for using as the components of the roof frame. When taking into consideration the proposed measures, it becomes possible to reduce the mass of the frame of the removable roof for a railroad gondola by almost 15 % compared to the typical design. At the same time, to apply the roof on different types of gondolas, its cantilevered parts can move in a longitudinal plane. It is possible to use deflectors on the removable roof. The roof can be attached to the body in a regular way. It is also possible to fix it using shog-connections. To substantiate the proposed solution, the strength of the improved structure of the removable roof was determined. It was established that the maximum equivalent stresses in the load-bearing structure of the removable roof did not exceed permissible ones. To define the indicators of removable roof dynamics, its dynamic loading was investigated. The calculation was performed in a flat coordinate system. The oscillations in bouncing and galloping were taken into consideration as the most common types of a railroad car oscillations when running on a rail track. The mathematical model of dynamic loading was solved in the Mathcad software package (Boston, USA). The study has shown that the acceleration of the body in the center of masses is 0.4 g and is within the permissible limits. At the same time, the ride of a railroad car is excellent. The study reported here would contribute to the improvement of the efficiency of railroad transportation.