Michela Turrin

Design explorations of performance driven geometry in architectural design using parametric modeling and genetic algorithms

In this paper we discuss the benefits derived by combining parametric modeling and genetic algorithms to achieve a performance oriented process in design, with specific focus on architectural design. The key role played by geometry in architecture is discussed in relation to performance oriented design, in which evaluations based on engineering criteria are integrated into the conceptual phase of the design. The performance attained by a specific geometric solution is considered along with its complexity in an interdisciplinarity process. A specific case study using large roofs is presented as an example. Enabling the designer to automatically generate a large range of alternative design solutions is a great advantage offered by parametric modeling in supporting geometric design explorations. However, this in turn presents the difficulty of how to evaluate the resulting myriad of generated alternatives. ParaGen is presented as a tool to support the exploration of the parametric design alternatives. ParaGen combines parametric modeling, performance simulation software and genetic algorithms, together with a database to store and retrieve the solutions for subsequent exploration. The design exploration is enhanced by means of the interaction of the designer with the process. This serves two objectives. Firstly, it addresses the genetic algorithm based creation of design solutions, while still focusing on a given fitness function. Secondly, it facilitates knowledge extraction from the generated solutions. A description of the tool and its possible uses by designers is provided. Applications of this tool are illustrated for both education and research, with specific reference to two examples in the field of modular long span roofs. The first case study has been developed as part of a teaching exercise in which ParaGen is used to explore the morphology of a dome based on structural performance. The second case study is derived from a research project which deals with solar energy transmission, and concerns the solar heat gain and daylight transmittance of a long span roof.

Sports building envelope optimization using multi-objective multidisciplinary design optimization (M-MDO) techniques: Case of indoor sports building project in China

Sports building envelopes are complex systems involving multiple architectural and engineering performance requirements that are sometimes in conflict with each other. Typically, daylight usage and energy efficiency, as two primary concerns in building envelope design, are of those conflicting aspects. To improve overall performance (including daylight and energy performance) by changing the geometries of the envelope, windows and shading elements as well as the selection of construction materials, Multi-objective Optimization (MOO) is a natural choice. Based on the generated Pareto front, trade-off decisions between competing performance objectives can be made. However, as the number of design variables from different disciplines increases, the huge design space and the specialization of disciplines make the optimization process less efficient. Therefore, two possible Multidisciplinary Design Optimization (MDO) frameworks, namely Individual Disciplinary Feasible (i.e. IDF, a single-level MDO framework) and Collaborative Optimization (i.e. CO, a bi-level MDO framework), are investigated to combine with MOO. Resorting to the capability of MDO in decomposition and coordination between different disciplines, parallel disciplinary simulations and/or bi-level optimizations can be realized, which compresses design cycle time and achieves better overall performance. Through the combination of MOO and MDO, Multi-objective Multidisciplinary Design Optimization (M-MDO or multi-objective MDO) problems are expected to be solved more effectively and efficiently. The whole process of the proposed method consists of three phases (i.e. preprocessing, solution and post-processing phases), in which variable screening, multi-objective MDO solving and Pareto front comparison are performed respectively. An ongoing real project located in China, is used as a case study to test the proposed method. For now, the research work is in the preprocessing phase. Preliminary observations and results are obtained, and future research is discussed.

Architectural DNA : A genetic exploration of complex structures

The approach demonstrated in this paper uses Evolutionary Computation (EC) to enhance and modify structural form based on biological micro structures. The forms are modified to conform to new boundary conditions associated with architectural structures. The process is based on a Genetic Algorithm (GA) which visually exposes for the designer a range of good performing solutions within the design space. The application of the GA is combined with parametric software, in this case Generative Components (GC). The program described here as ParaGen (Parametric Genetic Algorithm), uses a Finite Element Analysis (FEA) to determine the structural performance of the forms. This allows the designer to manipulate and optimize a parametrically defined model based on predefined criteria and parameters. The opportunities and limitations of this design process are explored and evaluated based on an experimental case study using topologies based on radiolarian skeletons. The design procedure described includes user interaction in the exploration of solutions that perform well both for the explicitly defined programmatic criteria (structural) as well as for the implicit criteria provided by the designer (visual aesthetic).

Impacts of problem scale and sampling strategy on surrogate model accuracy: An application of surrogate-based optimization in building design

Surrogate-based Optimization is a useful approach when the objective function is computationally expensive to evaluate, compared to Simulation-based Optimization. In the surrogate-based method, analytically tractable “surrogate models” (also known as “Response Surface Models - RSMs” or “metamodels”), are constructed and validated for each optimization objective and constraint at relatively low computational cost. They are useful for replacing the time-consuming simulations during the optimization; quickly locating the area where the optimum is expected to be for further search; and gaining insight into the global behavior of the system. Nevertheless, there are still concerns about the surrogate model accuracy and the number of simulations necessary to get a reasonably accurate surrogate model. This paper aims to unveil: 1) the possible impacts of problem scale and sampling strategy on the surrogate model accuracy; and 2) the potential of Surrogate based Optimization in finding high quality solutions for building envelope design optimization problems. For this purpose, a series of multi-objective optimization test cases that mainly consider daylight and energy performance were conducted within the same time frame. Then, the results were compared, in pair, based on which discussions were made. Finally, the corresponding conclusions were obtained after the comparative study.

Case Study ‘the Vela Roof – UNIPOL’,Bologna: Use Of On-site Climate AndEnergy Resources

The case study presented in this paper focuses on the so-called “Vela roof”. This roof is part of a larger project under construction in Bologna. The focus of the study concerns the use of on-site renewable climate (energy) resources for thermal comfort with special attention given to passive cooling and heating. The very first conceptual design developed by the architectural office is assumed as a starting point for the inclusion of performance criteria at this stage in the process, taking into account a large chain of dependencies that need to be integrated in the design process. Due to extremely low wind speeds on-site, early evaluations pointed out how wind should be caught in order to provide some cooling effect; secondly, side openings at the wrong location on the roof would contribute to a green house effect more than to a passive cooling effect. As a result, in the preliminary design of the roof uncomfortable conditions were highly expected under the whole roof in the summer, with an even higher critical level in the space between the lower buildings’ roof and the Vela. Two main issues of the Vela are therefore highlighted especially related to the improvement of the existing design (configuration and shape). On one hand, in the preliminary design the overheated air was going to be kept at the top enclosed spaces without being passively extracted. On the other hand, the system of side openings could be related better to the local wind behaviour. The latter has been analyzed and digitally simulated and the first results are presented in this paper. Integration of these main issues in larger strategies was also investigated, considering both active solar technologies and passive systems for heating and cooling.