Advances in digital fabrication and additive manufacturing have enabled the creation of geometrically complex glass structures and building components, opening up new design opportunities across scales. Quantifying and evaluating their optical performance, however, remains a technical challenge. In order to accurately predict light behavior, common approaches of daylight modeling utilizing light-backward raytracers are insufficient. This paper evaluates the use of the photon mapping approach within the Radiance render engine to simulate artificial and natural lighting conditions. 3D printed optically transparent glass components are used to benchmark the simulations. We present a workflow to gather geometric data of the glass objects and a series of validation experiments. Pairs of physical studies and digital simulations are compared to assess optical performance in the context of both indoor and outdoor lighting conditions. These experiments demonstrate that the photon mapping approach can reliably measure and predict caustic light patterns and indoor light levels with some limitations, specifically of glare and scattered light from the glass objects themselves. Image 1 • Complex glass structures cannot be simulated accurately with backward raytracing. • 3D printed glass structures are used to evaluate simulation performance. • A workflow for geometry capture and simulation is presented. • Photon mapping excels at simulating light behaviour with some limitations. • Interior light levels and caustic light patterns can be predicted reliably. [ABSTRACT FROM AUTHOR]
Santos, Luis, Schleicher, Simon, and Caldas, Luisa
Building & Environment. Feb2017, Vol. 112, p144-158. 15p.
Energy consumption of buildings, Computer-aided design, Computer graphics, Rapid prototyping, and Algorithms
This work presents a new methodology to automate the derivation of Building Energy Models (BEMs) from complex 3D Computer-Aided Design (CAD) geometry. The goal is to combine current parametric modeling, digital fabrication, and computer graphics techniques to automatically generate the geometric input of an energy model from any digital 3D model of a building. Such automation facilitates the use and implementation of goal-oriented design methods that integrate energy performance with other types of building performance models. In this work, mesh planarization algorithms, which are currently used in computer graphics and in digital fabrication methods, are used and adapted to automate and optimize the parsing of non-planar surfaces to EnergyPlus (E+), a popular BEM engine. The proposed methodology facilitates the modeling of thermal zones with double-curved envelopes, which is a time-consuming task that typically requires a high level of expertise from the energy modeler. The proposed single, streamlined workflow generates digital models that are suitable for both energy optimization and digital fabrication, thereby facilitating the integration of two parallel design procedures at the core of an architectural design process. Through this workflow, a single CAD model generates solutions that are energy efficient and feasibly fabricated using digital techniques. This goal-oriented design workflow is applied in the study of fritting pattern densities for three complex double-curved building geometries. [ABSTRACT FROM AUTHOR]
Scaled wind tunnel testing and Computational Fluid Dynamics (CFD) analysis were conducted to investigate the natural ventilation performance of a commercial multi-directional wind tower. The 1:10 scaled model of the wind tower was connected to the test room to investigate the velocity and pressure patterns inside the micro-climate. The tests were conducted at various wind speeds in the range of 0.5-5 m/s and various incidence angles, ranging from 0° to 90°. Extensive smoke visualisation experiments were conducted to further analyse the detailed airflow structure within the wind tower and also inside the test room. An accurate geometrical representation of the wind tunnel test set-up was recreated in the numerical modelling. Care was taken to generate a high-quality grid, specify consistent boundary conditions and compare the simulation results with detailed wind tunnel measurements. The results indicated that the wind tower was capable of providing the recommended supply rates at external wind speeds as low as 2 m/s for the considered test configuration. In order to examine the performance quantitatively, the indoor airflow rate, supply and extract rates, external airflow and pressure coefficients were also measured. The CFD simulations were generally in good agreement (0-20%) with the wind tunnel measurements. Moreover, the smoke visualisation test showed the capability of CFD in replicating the air flow distribution inside the wind tower and also the test room. [ABSTRACT FROM AUTHOR]