Introduction: Arduino Powered Moss&Solar Facade Element

The idea behind this unique facade element is to produce power AND to filter fine dust. We planed it to function autonomously and react to high fine dust pollution.The facade element is made of three rotating prisms.

The different surfaces of each prism are covered with moss, which can filter the dust out of the air, and photovoltaic modules to produce power. Sensors are use to control the automatic rotation of the element depending on the air quality. If the moss gets too dry the element will be turned to put the moss into the shadow at the back of the module.

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:


Cristin Schroeder, Maximilian Rein, Georg Röhl, Clemens Röhl

Step 1: Required Tools

  • CNC mill
  • laser cutter
  • wood glue
  • wood drill
    • 1mm
    • 2mm
    • 6mm
    • 9mm
  • superglue
  • duct tape
  • ruler
  • soldering bolt
  • screwdriver
  • hacksaw
  • wire stripper
  • blow drier

Step 2: Required Components

frame: 525mm x 525mm x 280mm (we got this at the beginning of our project, see picture)

Arduino Uno

3x stepper motor (we used Stepper Motor with Cable)

3x motor driver (we used A4988)

3x ball-bearing (we used SKF BA 9)

optical dust sensor (we used GP2Y1010AU0F)

luminosity sensor (we used TSL2561)

RGB-LED (we used WS2812-Breakout)

temperature sensor (we used NTC Thermistor 4.7k Ohm B57164K)

3x reed contact (we used reed contact)

3x photo voltaic panel 465mm x 160mm (we didn't get these)

coaxial power connector male (we used Steckverbinder-Buchse)

12 V/DC power supply 1000 mA (we used Stecker-Netzteil)

valve-regulated lead acid battery 12 V 0.8 Ah (we used this) + charging control

150ohm resistor

220uF capacitor

a lot of wires + shrinking hoses

9x M3-16 thread screw

18x M3 nuts (we used: Sechskantmuttern DIN 934 M3)

plexiglas 240mm x 80mm x 5mm

steel rod 6mm ø x 42mm

plastic tube 9mm ø x 7mm ø x 102mm (we used two old pens)

moss: 465mm x 633 mm

3x magnets

3x washer

3x small hinge + screws

2x soil moisture sensor (we built our own with these instructions)

10mm MDF:

  • 2x : 525mm x 525mm (inner and outer back panel)
  • 1x: 525mm x 145mm (top panel floor box)
  • 6x triangle 115mm side length

5mm MDF:

  • 1x: 525mm x 150mm (top panel)
  • 3x 465mm x 160mm ('solar side' of prisms)
  • 3x: 465mm x 108mm (moss side of prisms)
  • 3x: 465mm x 103mm (moss side of prisms)
  • 1x: 525mm x 40mm (front panel floor box)
  • 1x 525mm x 30mm (back panel floor box)
  • 1x 455mm x 30mm (middle panel floor box)

sawing template.pdf

Step 3: Wiring

In this section you can see all the wiring in detail. We will later only explain which electronic parts we connect. So regard this picture if you want to know how to connect one of the sensors or the motor drivers.

We also attached the sketch as pdf file to give you a more detailed look.

Step 4: Prepare the Hardware - Gears and Floor Box

As our project is very unique we decided to laser and mill some things on our own:

4.1) make annular gears and gearwheels:

Take the Plexiglas to your laser cutter and make three annular gears which will end up in the top panel of the floor box and three gearwheels for the stepper motors. (see the file 'laser template')

4.2) prepare the "floor box":

4.2.1 top panel of the "floor box":

Next you need to mill three notches into the top panel so you cant see the annular gears from the front side. In the center of the notches you should leave some wood so the ball-bearing will stay there. (see the file 'milling template')

Afterwards drill 9mm ø holes into the center of the notches so we can put cables through this axis. And you need to drill the holes for the reed contacts. We got another template for that. (drilling template top panel floorbox)

4.2.2 front panel of the "floor box":

We decided to mount the electronics (except the moisture sensors and the motors) into the "floor box". The front panel will hide the ugly electrical things and will let in air to the dust sensor and the light of RGB-LED out. Use the 5mm MDF 525mm x 40mm from the components list and drill a hole into it. Then mill a square on the right edge into it. That's how we get an even front surface although we are mounting the luminosity sensor onto the front.

4.2.3 back panel of the "floor box":

Here you only needed to drill one hole to be able to put the wires for the DC connector through.

Step 5: Prepare the Hardware - Turning Prisms, Rotation Axis and Back/top Panels

5.1) prepare the three turning elements:

The footprint of these elements are triangles. Use the drilling template to make the holes into three triangles (for the motor axis, the screws to mount the motor and the rotation axis where the cables go through). The other three triangles (for the top end) need each only one 6mm ø hole for the rotation axis. This has to be only 5mm deep and not the whole way through. (see 'drilling tamplate triangles.pdf') To get the cables to the solar panels you need to drill another 2mm hole into the wider siedes (465mm x 160mm) of each prism. For the soil moisture sensors we only need wholes in one of the turning prisms on the two smaller sides.

5.2) the rotation axis:

Cut the 42mm steel rod in three equal 14mm pieces. The 75mm plastic tube should be cut in 3 pieces á 9mm and 3 pieces á 25mm.

5.3) backpanels / top panel:

Next you need to drill a hole into each back panel (the inner and outer big square 525mm x 525mm). Into the former for the DC wires and into the latter to mount the DC connector in it. Last but not least drill three 9mm holes into the top panel for the axis mounting with this drilling template: (see 'drilling template top panel.pdf')

Step 6: Start Building: the Three Turning Elements -> Prisms

If you had a look at the 3D-file of our element there isn't much to say about building the three turning three-face prisms. You should have all the parts near you and then the only other things you need are a screwdriver, wood glue and some time.

To make it easy for you we created a time lapse video when we built one of our turning elements. At the beginning you can see all the needed parts and in the end you can see one finished element.

To sum it up in a three quick steps:

  1. mount the hinges on one of the smaller pieces
  2. glue the triangles and the 2 smaller panels together
  3. mount the wider panel with the hinges to rest

NOTE: In the video you can see us gluing in a third triangle in the middle of the module. We did this because we thought it was to unstable without it. But after finishing the three modules we now know: The modules are stable without the middle triangle.

Now you can put the stell rugs into the top triangles and attatch the longer (25mm) plastic tubes to the bottom triangles. You should also glue the top element of the ball-bearing onto it.

Next you should put all the cables you need inside the prisms through the axis which are:

  • for the motor
  • for the photo voltaic panels
  • for the soil moisture sensor

Now you can mount the motors into the three-face prisms. If you take a close look at the 3D-file or picture this picture

you can see that we used the nuts to get the right spacing between the motor and the bottom triangle.

Next up are the magnets and washers: Each element gets a pair of magnet and washer as closing mechanism for the 'door' and to trigger the reed contact. We used the superglue to fix them to the right places.

Step 7: Build the Floor Box

Start of by flipping the top panel to the side with no milling done and glue the front, the middle and the back panel onto it.

(The spacing between front and middle panel is 50mm.)

Next glue the annular gears and the bottom of the ball-bearings onto the other side.

Then you can put in the reed contacts and use some duct tape to fix the cables at the bottom.

Step 8: Lets Put the Pieces Together

This part is a bit tricky. You should have at least 6 hands to do this step. So go ask some friends for help. We put the inner back panel on the table and the prisms on it. Pulled the cables through the middle part of the ball-bearings and then through the holes in the floor box. The next step is to first glue floor box to the panel and then glue the top panel, too.

Now your module should look like this:

NOTE: This pictures are from a prototype where the magnets were located differently, don't get irritated by that.

Step 9: Soldering

As we described the detailed circuit layout in step three we just made another video to show you how we did the soldering.

Afterwards you can connect the battery with the charging control as well as the solar panels to the circuit.

Step 10: Programm the Arduino

When this is done you should push your construction into the frame.

Step 11: Further Ideas and Information

We attached an pdf with information on vertical moss growing.

Furthermore this is only a prototype and probably not suitable for outside use because the wood would swell. We think you should probably use stainless steel or some kind of plastic for this.

We also planed the module to have room for insulation. That's why we only used the half dephts of the module.

Home Technology Contest

Second Prize in the
Home Technology Contest

Epilog Challenge VI

Participated in the
Epilog Challenge VI

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Participated in the
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