Cardboard Model of a Passive Solar House

In my Design for Enviromental Good class we learned about the characteristics of a passive solar house. We afterwards chose specific aspects of these and designed a house focused around them. In this post, we will learn how to make a passive solar house out of cardboard, and how to wire it so it runs solely on solar power.

Tools and Materials List

Tools:

1. Exacto knife
2. Pencil
3. Soldering Iron
4. Hot glue gun
5. Wire cutter/ stripper

Materials:

1. Cardboard (1 very big box)
2. Solar panels (2, 12 volts 0.2 amps, 1, 20 volts 0.4 amps)
3. Hots glue sticks (as many as necessary)
4. Solder (1 wheel of lead-free solder)
5. Alligator clips
6. Wires (5' of 16 gauge wire)
7. Switch with USB (1)
8. Switches on wire (2)
9. Masking tape (1 role)
10. Loads (2 fans, 3 LED's)
11. Resistors (3, 220 Ohms)
12. Euro splicer (1/2)
13. Portable charger (1)
14. Portable charger's charger (1)

Firstly you need to research some of the elements of a passive solar house, and decide which ones you want to incorporate. Then you can start sketching your house. I found that it was helpful to look at photos and other peoples sketches to get inspiration. It is most important to incorporate windows which should be south facing to get light and heat in the winter, overhangs to block the summer sun from entering the windows, and some sort of ventilation method for the summer heat. If designing a real house, it is important to learn about insulation, but thats not necessary for a cardboard model. I decided to incorporate south facing windows and solar panels, a clerestory, and the stack effect for ventilation. While designing my house, I also had to take into account the maximum panel tilt for my area, which is around 33 degrees, the size of the plot of land that I was given which was 19.5 by 34 inches, and the orientation of my house, so I know which way is south. Once I took these into account, I sketched a house design with a double roof split by a clerestory, a big family room/kitchen, a smaller bedroom with a bathroom behind it, and a small porch in front. It is also important to know what size each room is going to be and the height of all the walls. After this step you should have a clear idea of what your house structure is going to look like.

I started out by cutting the basic floor piece with an exacto knife, making sure to measure so it fit. I then cut the back wall and both side walls, then taped them onto the floor. For my house I decide to leave one of the long walls open so that I could see into my house, and the other one windowless, so that I could attach my future circuit to that wall, but it is up to you if you want to leave a wall open. The 2 walls left were south and north facing, so I added lots of windows and a door to my south facing wall, and only a few windows to my north facing wall for natural indirect sunlight. Once I added windows, I hot glued the 3 walls to the floor piece and then I built my middle wall that seperates the main room from the bedroom and bathroom. This wall is taller so my roof becomes slanted toward the bedroom and bathroom side. I then added a double clerestory on top of this where my other roof will connect. After I finished cutting out windows and doors, I hot glued all of my pieces together to finish the out line of my house. This is just how I decided to build my house, and yours should be different and unique. It is important to note that while I built my house my design changed a lot based on limits of the material, and better design ideas, but thats ok. Your house should incorporate the passive solar principles that you chose to use, so it will probably look different. Make sure to also add an easy access point for when we build a circuit. You can add furniture at this step if you would like.

In this step I will show you how I planned my circuit out. Firstly I started at the energy source or the supply which was the 3 solar panels. I knew that I wanted to wire them in parallel, so I could get more amperage, and less voltage. I then would connect them to a switch before I connected them to the portable charger or battery so that my house could be solar or battery powered. This switch would connect to a eurosplicer so that I could split the wire into 2 seperate circuits. One circuit would lead to my LED's, which I would wire in parallel and the other would lead to my fans which would be wired in series. This was my overall idea for how I was going to wire my house, and was a necessary step for planning, so that I had a strong layout for an idea for when I started soldering.

It's now time to build the circuit that will bring electricity to your cardboard model. I again started by connecting the solar panels. To connect them in parallel, I connected all 3 red wires and all 3 black wires with clips. I didn't solder mine since they're going to be reused, but you can solder them for more strength and reliability. I then grabbed the battery's charger and used an exacto knife to cut off the USB side. With that, I stripped the outershells off using my wirecutters, until I had the copper wires from the red and black sides showing that I could connect to the solar panels. I found that it was easiest to strip wires by lightly cutting the outside while rotating the wire in a circular motion, then pulling the shell off once I had cut deep enough. I added these 2 ends to the cooresponding colored clips, and connected the charger side to my portable charger. The next step is to take one of the switches, and again cut and strip one side until the copper wires are showing. Make sure not to cut the USB side this time, rather the charger side. Connect the USB side to the charger and leave the other side for now. We can now make one of our 2 circuits, the fan circuit. This one only involves stripping each of the wires on the fan if they don't come stripped. We then have to solder these 2 together. To solder you have to be very careful, and I suggest watching a beginner video for safety and tricks. For my project I used lead free solder, but it is up to personal choice. Also always wear safety goggles. Once 1 side is soldered together, solder a switch in too and set this aside with the other stuff. The last circuit we have to make is the LED's. I cut two 6' pieces of my generic wire and stripped each side of it, making one side about 2 inches long on each. With this, I laid out my 3 LED's and soldered one side of each LED to one wire, then soldered the other sides to the other wire. At the end of 1 of the wires I also soldered a switch on. With our 2 load circuits we can now add an end from each of the circuits into the eurosplicer, and the other 2 ends into the other side of the splicer. On the back side add the original circuit connecting to the battery, and then you've completed your circuit.

You're almost done, you just have to add your circuit into the house. I decided to cut a hole into the back wall of the bathroom to store my whole circuit, but this is optional because you can store it anywhere. For my house, I also had to add cardboard to support the solar panels, a box to store the wires coming off of the solar panels, and a holder for my portable charger. While installing my circuit, I used my exacto knife to cut tiny holes in the corner of rooms to thread the wire through, and masking tape to tape the loads to the roof. I put 1 fan in the bedroom, and my lights and another fan into the main room. I stored all remaining cords and wires in the bathroom, and cut holes on the bathroom walls for my switches so that they could be visible from the outside. Once I finished this my house was done and ready to be tested. Everything should work as expected. Now, we've successfully finished our solar house model. Congratulations!