Prototype component for a data-driven 2.5-dimensional façade to increase visual comfort

Liss C. Werner

Prototype component for a data-driven

2.5-dimensional façade to increase visual comfort

Open Access via institutional repository of Technische Universität Berlin

Document type

Conference paper | Accepted version

(i. e. final author-created version that incorporates referee comments and is the version accepted for publication; also known as: Author’s Accepted Manuscript (AAM), Final Draft, Postprint)

This version is available at

https://doi.org/10.14279/depositonce-12168

Citation details

Werner, Liss C. (2021). Prototype component for a data-driven 2.5-dimensional façade to increase visual comfort. In: Williams, Kim; Leopold, Cornelie (Eds.): Nexus 20/21 – Architecture and Mathematics. Kim Williams Books, ISBN 978-88-88479-49-1, pp. 187–192.

Terms of use

c bThis work is licensed under a Creative Commons Attribution 4.0 International license:

https://creativecommons.org/licenses/by/4.0/

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Introduction

Contemporary office building facades usually offer an equal distribution of the same modules across a facade; some act as windows, others remain closed panels. The impact of sunlight within the building differs across the facade; the larger the area is, the larger the impact. As a result, visual comfort inside of a standard office building can only be achieved through additional mechanical devices, such as blinds. In their study Sun et al. (2019) suggest “that it is necessary to design personalized illumination environment for particular workplace” to increase productivity. The quality and quantity of light within a given space is referred to as Visual Comfort.

The current state in standardized natural lighting in interiors is explained in the CEN European Daylight Standards EN17037 (Darula 2018) Relevant parameters are:

1. Daylight and visibility, assessing whether an interior warrants visual comfort for users.

2. Spatial daylight autonomy (sDA) examining whether a space receives enough daylight during daily occupation hours annually.

3. Annual sunlight exposure (ASE) intending to help designers limit excessive sunlight in a space.

4. Daylight factor (DF) measuring the subjective daylight quality in a room;

describing the ratio of outside illuminance over inside illuminance.

5. Daylight glare probability (DPG) index considering vertical illuminance at average human eye level.

A disturbing glare arises when a person looks out of a window toward the sun or when direct sunlight reflects on surfaces that are in the person’s field of vision.

Discomfort results from both low levels and high levels of lights, as well as unstable light intensity. This may cause human eye fatigue. Marta Benedetti et al, in a specifically targeted study, investigated the “light’s direct influence on human physiology, cognitive performance and mood” (Benedetti et al. 2019). Low visual comfort in existing office buildings and correlated performance and well-being was the starting point of the project.

Two prototypes for a façade module acted as proof of concept. A digital prototype (simulation) representing an optimized geometry across a façade driven by data in accordance to the EN17037 and a physical prototype. The latter materialized part of one optimized facade module. It served for understanding the architectural and spatial quality of such a geometry, with focus on scale, producibility and various possibilities of digital tectonics and assembly logic. A computational workflow within limited

1 Institut für Architektur, Technische Universität Berlin, Germany, liss.c.werner@tu-berlin.de

2 L.C.WERNER, Prototype Component for a Data-Driven 2.5-Dimensonal Façade to Increase Visual Comfort

domains for Euclidian transformations on top of a transformable geometry provided numerous iterations with different attributes.

An evaluation and final geometry of openings in the facade modules was enabled by introducing evolutionary solvers. Goal was to design and then optimize a modular triangulated facade that would increase visual comfort on one hand and act represent an architecturally articulated facade on the other. The different positions of the modules resulted in a 2,5-D facade with unique elements. The paper presents a case study showing the workflow for a performative facade element informed by driven visual comfort input data.

The Research 1. Case Study Set-Up

The case study was carried out utilizing the west-facing facade of the building of the Institute of Architecture at Technical University Berlin. The building was designed by Bernhard Hermkes and constructed in 1963- 1968. The city of Berlin is located on 52,5200N latitude with a low position of the Sun during the winter months October to March. The facades of the prefabricated concrete building are equipped with large glass- panes adjacent to each other. Thus, interior spaces can be exposed to disturbing glare through natural sunlight. The carried-out daylight analysis of the case study façade showed an average daylight exposure of 4-6 hours daily. In the research each opening was to receive a new ‘cover’, collectively acting as a secondary skin. The preliminary analysis of the west-facing facade identified six different types of modules–varying in length and height. A type with the dimensions of 6.20m-3,20m was chosen. Planar triangulation allowed for structural soundness, sought after aesthetics and sufficient flexibility to arrive at a 2.5-dimensional structure, that could be described as vertical topographical landscape (Werner 2017).

The surface of each module was defined by folds, faces, edges and vertices. The corners of the rectangle were set as anchor points, while the diagonal was initially populated with six deployable points; three for the panel on south-top (ST) and three for the panel on north-bottom (NB). A drawn line from every other respective anchor point to the deployable points resulted in a second level of triangular resolution. By moving the deployable points along the local XY plane, the geometry started shaping, and creating voids for controlled light distribution. Introducing the local Z motion axis for the deployable points allowed increased flexibility in designing a 2,5-D geometry (Fig. 1).

Limited domains guaranteed both, freedom of movement and avoidance of collision between the elements themselves or the elements and the existing building. The geometric flexibility and fabrication potential (due to a large panel size) as well as the resolution of the triangulation was not considered as sufficient for the intended design quality. An additional layer of increased triangulated square grid resolution on each face was added. The result was an origami-like façade (Bellamy et al. 2019) (Andreozzi et al. 2016) proving flexibility, showing a certain level of curvature, the likelihood of industrial digital producibility and functioning towards an increase of visual comfort, e.g. shading. (Pesenti et al. 2018).

Fig. 1. Left) the division of the secondary facade module in elevation; right) the perspective.

It was divided by a diagonal into two regions: south top and (ST) and north bottom (NB) 2. Methodology and Optimization

Evolutionary solvers for multi-objective optimization were introduced to the design process as a methodology to generate a number of geometric possibilities to be analyzed and evaluated; (Mirjalili et al. 2018) at a later stage also against objectives that the solver cannot cover. ‘Daylight autonomy’ (sDA) and ‘Annual Sunlight Exposure’ (ASE) were chosen as objectives for the optimization. ASE was maximized and sDA was minimized. The NB hardly influenced the solution;

therefore, the optimization process considered the ST only. It was constructed of four adjacent primary triangular faces with a secondary layer of nested triangulation within each face. The genomes of the solver were the deployable points on the diagonal of the openings (Fig. 1, right). The position of the ST points moved 3- dimensionally whereas the Z value was absolute.

To perform the optimization a test plane was divided into equal squares measuring 0.7 m edge length. Figure 2 shows the sDA on the test plane for each floor.

Algorithmic possible solutions were presented in a 2-dimensional solution space (Fig.

3) where each solution is the most feasible and optimal according to defined fitness.

Figures 4 and 5 show a visualization of the solution finally chosen.

4 L.C.WERNER, Prototype Component for a Data-Driven 2.5-Dimensonal Façade to Increase Visual Comfort

Fig. 2 (left and center) Daylight Availability on 31.10.2018

Fig. 3 (right) Diagram showing possible solutions derived through iterative fitness testing, whereby solution s2 was chosen

Figure 004: part of the façade elevation after optimization

Fig. 5. Chosen solution based on MOOS (multi-objective optimization solvers) showing a variety of daylight exposure across four façade modules

3. Fabrication

Fabricating a physical prototype was intended to understand architectural and design qualities, scale, possibilities for tectonics and geometric amendments and industrial producibility. The prototype, a part of a standard module (6.20 m–3.20 m), measured 1.80 m x 2.30m and counted 47 triangular components (Fig. 6). Geometries were nested manually on three 2050 x 1250 mm plates of 16 mm thick MDF (Fig. 7).

Fig. 6 (left) Unfolded front elevation with fabrication tagging logic and folding angles Fig. 7 (right) Nesting on MDF panels for minimal waste

A tool, such as the plug in opennest in Shape Diver for Grasshopper, automating nesting would have optimized the cutting of the components (Hemmerling et al.

2018). It applies single objective optimization to reduce the amount of waste material and cutting time by computing an efficient component layout on the sheet material and economic cutting path. The components were cut on a standard CNC machine.

Assembly logic was simplified by tagging corresponding edges with to locate each component during the assembly process. Each letter had an angle assigned to it to identify the pre-defined angle between adjacent components. Pre-bent metal strips fixed to the back of the components facilitated the correct angularity. The strips were bent using an analog swivel-bending machine. Using standard bolts timber components and metal plates were connected. The prototype was presented at the Make City Festival in Berlin in Summer 2018.

Conclusion

The paper introduced a process of parametrically designing, fabricating and constructing a prototype module for a secondary façade. A morphing geometry spanning across the facade was achieved through combining European standards for visual comfort with the design approach of triangulation. The design methodology included multi-objective optimization solvers. A functional evaluation of the façade increasing visual comfort was carried out digitally. An architectural evaluation of the geometry was carried out by manufacturing and testing a physical prototype of a partial module. A first step toward a proof of concept for enhancing visual comfort in existing office buildings through a data-informed-parametrically designed façade geometry was achieved. A desired architectural expression of a building in the urban landscape through the application of morphologically changing geometry on a global and local (component) level was accomplished. The work opens up new research on the feasibility–economical, technical, architectural–of producing secondary facades that combine digital automated data input and architectural design principles to finally present a high level of function through geometric articulation.

6 L.C.WERNER, Prototype Component for a Data-Driven 2.5-Dimensonal Façade to Increase Visual Comfort

Fig. 8 (left) Assembled prototype 1.80 m x 2.30 m

Fig. 9 (top right) Assembled prototype showing assembly logic tags Fig. 10 (left) Detail assembled prototype

Acknowledgments

The Project was funded as part of the activity ‘Built by Data’ Project ID18101 by the European Union through Horizon 2020, EIT Digital.

Participants: Pawel Unger, Suryaveer Patnaik, Valmir Kastrati, Stefanie Holzheu, Theresa Lohse, Louai Samah Mesharrafa, Narjes Ghasghaei, Gülsah Dumaz, Adrian Krezlik and Parametric Support, ARUP.

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Bellamy, A. et al.2019. Towards resilient adaptive origami-inspired diagrid building envelope. Paper presented at the Active and Passive Smart Structures and Integrated Systems XII.

Benedetti, M. et al. 2019. Impact of dynamic lighting control on light exposure, visual comfort and alertness in office users. Paper presented at the Journal of Physics:

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Hemmerling, M. et al. 2018. Design to Production. In: Informed Architecture, M.

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