The goal of this project was to develop intelligent skins for houses. More specifically addressed to the needs of learning environments. We aim to build a window with the ability to automatically detect bright light and shade itself as a result.

We considered using both electrochromic glass or polarizing films for shading the window. The mechanical solution using polarizing films offers the possibility to continuously adjust light transmission and therefore improves usability. Because of this and because of the high cost of electrochromic glass we went for the latter one.

The basic idea is twisting one polarizing film against another. When both films are perpendicular to each other the window is shaded, when both are parallel the window is transparent. We employ a luminosity sensor in order to trigger the rotational mechanism.

For the prototype we used plain film with stripes on it to demonstrate the functionality of our window, this further reduced the cost of the prototype. In reality polarized films should be used in order to assure the desired functionality.

This project was part of Multimodal Media Madness 2014, hosted by the
chair for Computer Aided Architectural Design (CAAD) and the Media Computing Group of RWTH Aachen University. For more Thinking Skins, please check this page: http://hci.rwth-aachen.de/m3_ss14

Step 1: Get necessary components

Technical supplies / Electronics

1x Arduino Uno

1x NEMA 8 stepping motor

1x stepper motor driver

1x luminosity sensor

2x photoconductive cells

2x 5mm LED

2x 1k ohm resistor

2x 270 ohm resistor

circa 25 m wire, (1 x 0,14 mm^2)


Other supplies

1x material for the frame

1x MDF, (500 mm x 500 mm x 5 mm)

1x wood, (300 mm x 300 mm x 20 mm)

1x spray paint (e.g. silver)

12x wood screw, 3,5 x 35

3x M8 screw, 55 mm

11x M8 washer, 30 mm

6x washer, suitable for ball bearing (still able to turn, when put between two washers)

3x M8 ball bearing

3x M8 screw nut

4x M2 screw, 20 mm

4x M2 washer

3x felt pads (for furniture), 20-25 mm diameter

1x glow stick connector (inner diameter 5 mm, length ca. 25 mm)

fabric of an adhesive bandage

1x colored card, black (562 mm x 562 mm)

2x plexiglass, (562 mm x 562 mm x 3 mm)

2x polarized film (500 mm x 500 mm)

1x square timber, (45 mm x 15 mm), length 525 mm

2x square timber, (45 mm x 15 mm), 262,5 mm

2x square timber (5 mm x 10 mm), length 100 mm

1x square timber (40 mm x 10 mm), length 100 mm

1 x square timber (5 mm x 40 mm) length 300 mm

4 x wood screws, 2 x 16

2x nails, 1,2 x 20

wood glue/ hot glue

1x plywood, 3 mm (522 mm x 200 mm)

cable holders


heat shrink or insulating tape

hook-and-loop tape



milling machine


folding rule

sand paper

electric drill

drill heads in the sizes 2,5 mm, 3,5 mm, 5 mm, 8 mm and 10 mm drill heads



soldering iron


wire stripper



You can turn it by hand as well
<p>This is really interesting project! I'm very curious about different smart skins now...</p>

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