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Wout Parys • Piet Houthuys
Today’s building enclosures face ever greater demands regarding their thermal performance. In cold climates, the required total U-value of the façade is often very low. With thicker insulation layers, the relative impact of thermal bridges increases. Point thermal bridges, such as façade anchors, are due to single penetrations of the insulating layer. More and more, their impact is required to be calculated to account for the heat loss through them.
At the same time, BIM (Building Information Modelling) and the proliferation of easily accessible modelling tools such as Rhino have made 3D modelling of building enclosures pervasive. Performing a thermal calculation of a façade containing small point thermal bridges is however not straightforward, as this poses a 3D problem with large differences in the level of geometrical detail in the model.
In this paper, a new meshing algorithm is described that allows to solve complex 3D thermal problems consisting of larger models containing smaller, significant, details. The meshing algorithm is adaptive, creating non-conformal meshes with smaller meshes in some areas and larger meshes in others. This new meshing algorithm is implemented in SOLIDO, by Physibel. When importing STL geometries of a façade in SOLIDO, the new meshing algorithm results in thermal models consisting of a smaller number of calculation nodes. The significantly lower calculation time is shown in a case study of the calculation of a balcony slab thermal bridge.
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Vito Lamberti • David Russell Lehrer
This paper describes the development of an interactive map that highlights case studies of advanced facade design strategies and technologies from around the world. The overarching goal of this project is to disseminate information about best practices for climate responsive building design as showcased through facades. The non-profit project, led by the Center for the Built Environment at UC Berkeley and the Polytechnic University of Bari, Italy, was launched in 2020 and aims to serve design professionals, students, academics and others.
This curation process required the authors to grapple with numerous subjective and objective measures, and defining exactly what constitutes a high-performing facade. (Can a glass curtainwall in a desert climate ever be considered an appropriate solution?) The authors deliberated about what performance metrics can be applied in the selection process, while also allowing for a wide range of innovative and diverse examples. The authors ultimately focused on nine facade considerations relevant to the creation of sustainable and comfortable buildings: daylight and solar control, natural ventilation, noise control, embodied carbon, energy generation, and innovative insulation systems.
An additional goal of this project has been to include as much detailed technical information as possible. As part of this process, the authors devised a comprehensive taxonomy of building and facade data. This taxonomy has been integrated into the map and website design, so users can filter the case study projects based on the characteristics of interest or relevance to a specific investigation or design question. To capture such detail, an online form allows design team members, who are generally the gatekeepers of such technical details, to directly and conveniently provide project information. Such information has been provided by team members from firms such as Foster + Partners, DIALOG and Transsolar/KlimaEngineering.
The project has been online since 2021, and the project team continues to identify and add projects, at https://facademap.cbe.berkeley....
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Andrea Zani • Jamie Reyes • Guido Lori • Jacob Hanke • Giacomo Zangiacomi
In recent years, the desire for increased performance, transparency and visual flatness of glazing elements in curtain walls has generated renewed interest in thermally induced fractures. Glass fractures are one of the causes of premature failure in glazed curtain walls. They typically occur under climatic conditions that induce a large temperature difference across the glass. Once the glass tensile capacity is exceeded, fractures can appear across the glass pane. As a consequence, glass replacement is required, associated with high costs and inconvenience for the end-users. During design, approximate tools are available to assess the expected temperature gradients that the glazing might be exposed to, however, they sometimes fail to adequately evaluate the actual induced thermal stresses. Additionally, current standards lack uniformly defined procedures and often carry simplified assumptions that lead to over-conservative results. Modern complex building envelopes often require the use of detailed calculations and simulation methodologies to more accurately estimate the risk associated with thermal stress fracture.
This paper presents an advanced simulation workflow to accurately assess the temperature and stress distribution in glass lites for complex curtain wall applications. First, the project climate conditions are examined: exterior air temperature and solar radiation. Second, a 2D steady- state heat- transfer analysis is completed, followed by a simplified 2D transient simulation considering typical year weather data to identify the high risk boundary conditions. Lastly, a refined 2D-3D transient thermal model is created, whose outputs are translated into thermal stresses on the glass surface and edges through mechanical finite element modeling. This combined thermal-mechanical analysis allows for a more accurate temporal and spatial assessment of the temperature and stress distribution on each glass lite compared to typical linear approaches.
This paper presents a case study to showcase the proposed workflow and prove how 2D steady state assessments tend to be more conservative by 50-60% when compared to 3D transient assessments. And lastly, how calculated thermally induced stresses through current standards tend to be about 70% larger when compared to a combined thermal-mechanical analysis.
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John Medina • Jorge Moya • Maria Moral • Guillermo Saavedra
Building façade inspections have multiple objectives, such as forensic investigation of a failure, maintenance code compliance, etc. Architects, Engineers, and technicians doing façade inspections must gather all the technical information needed to be used by others. General contractors, building managers, lawyers, and other forensic investigators use this information obtained during the façade inspections. The results of the façade inspections must be clear, objective and traceable.
Traceable information requires that every deficiency/defect receives a unique identification that allows other professionals to follow its evolution since the day it was discovered/reported, up to the day when it is addressed. The data management aspects of traceability identify and reference the necessary requirements for capturing and sharing data using a simple model.
This simple model has been developed. This method can be used to report and trace all the deficiencies discovered during façade inspections. This method is based on the use of databases that allow for the identification of every deficiency and links all the information that must be prepared for others. The deficiencies are recorded according to the severity of the defect and the time required to be resolved. The simplicity of the software’s interface accelerates the data entry and the management of the information. The database software responds to these questions: What (what is the deficiency?), Where (where is it precisely located in the facade?), When (required time for repair?), and Who (who is responsible for the defect and/or repair?).
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