Superposition Reflective Louver

A Bio-inspired Daylight System for Atriums

One of the most fundamental issues in modern architecture is the provision of indoor illuminance using daylight, especially in the deep spaces that are far from the openings. In nature, organisms are equipped with some unique strategies to manage light for survival. Nature consistently considers the optimal response to take advantage of environmental conditions. In the this study, reflecting superposition, the process of lobster vision in directing light toward the retina, is investigated as an optimal solution for directing light through architectural space. First, the function and structure of a reflective superposition eye are studied and practical biological principles are extracted from relevant biological databases. Then, these extracted principles are applied in the design of reflective louver, and considering the climatic and operational parameters, the process of simulation and parametric design of the reflector louver is described. Finally, the data extracted from simulation stage are evaluated and directly compared to the base state. The results indicate an appropriate performance of the designed louver in improving atrium illuminance.

You can find the full paper here:

DOI: 10.1061/(ASCE)AE.1943-5568.0000414.

Superposition Eyes of Decapod Crustaceans

Although most of the optical structures of eyes are based on the refraction process and most compound eyes have one lens in each channel, the eye of long-bodied decapod crustaceans such as shrimps, lobsters, prawns, sea crabs, and crayfish uses reflection instead of refraction. In fact, the optical structures of these creatures’ eyes are square structures made of homogeneous jelly with a low refractive index. The jelly blobs are not lenses but rather are silvered and so can be called “mirror boxes”

Extracting the Biological Principles

Biomimicry of nature can be classified into five different fields:
(1) Mimicry of Form; (2) Mimicry of Material; (3) Mimicry of Construction; (4) Mimicry of Process; and (5) Mimicry of Function. In the biomimicry of the lobster’s eye, biological principles related to form (structure) and function are particularly noteworthy, which are discussed in the paper.

The structural principles of decapod eyes include the general form, geometry, and proportions of the biological structure and its components. On the other hand, there are two main interesting approaches in the study of the functional principles of superposition eyes: (1) the number of times that light beams are reflected from the faces of the mirror box; and (2) the direction of incoming light rays.

Bio-inspired Reflective Louver Design

The bio- inspired reflective louver is expected to have an optimal function in directing the light coming from a variable radiation source (the sun). To design and analyze this structure, it is necessary to simulate this structure in software with parametric design capabilities. In this study, several plugins of Rhinoceros software were used: Grasshopper for simulation of the louver geometry, and Diva and Ladybug plugins for simulation and analysis of illuminance, sun path, and light rays path in the atrium well.

The goal was to design the optimal reflective louver structure in terms of form, proportions, and performance to increase the illuminance on the base of the atrium during the day and year. The defined numerical variables include the curvature variable, the angle of the louver to the horizon line, the number of network divisions, and the proportions of a prism’s faces.

Optimal reflective louver simulation algorithm in Grasshopper.

Alternatives to a sphere sector models. In the algorithm, the points are defined as fixed and the radius of the sphere is defined variable (simulated by the authors in Grasshopper).

A basic 3D model of designed superposition reflective louver installed on top of an atrium.

Data Extraction & Analyze

Finally, the data obtained from the simulation of this structure should be evaluated scientifically. To this end, the average of illuminance level and the distribution of light at the atrium base floor in the two modes of with and without (basic mode) reflective louver are compared. As shown in Figures, the reflective louver improves the distribution of light on the base of the atrium, and in all cases, most points receive the desired illuminance level of 200–500 lx.

Daylight distribution diagram on the base of the atrium. Comparing two different modes without the reflective louver(Left) and after installing the reflective louver(Right) .

Simulation on the first day of the first month of each season (solar month) at 9:00 a.m., 12:00 p.m., and 3:00 p.m. (simulated by the authors in Diva and Grasshopper).

Average illuminance level on the atrium base floor on the first day of each season. Comparison of simulation data of base atrium with and without reflective louver.

Physical model: How a bio-inspired superposition louver can help to improve daylight distribution in atriums.

More details and information is available on ASCE Library: (DOI: 10.1061/(ASCE)AE.1943-5568.0000414.)