Insulating Cooking Skirt

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Our team (from left to right): Marcus, Zack, April, and Kylie

Marcus: I am a fifth year Agricultural Communications student with an interest in business. I love to participate in intramural sports with my friends and create music in my free time. I am currently on track to graduate in Spring 2016 and plan on working in sales for Oracle in Redwood Shores, California after graduating. I had very little experience with developing appropriate technology prior to taking PSC 392 and embrace each challenge faced when creating our design with open arms.

Kylie: I am a third year Journalism student who has an interest in design and the arts. I love to paint, write and create contemporary graphic design. I am currently a designer for Mustang News and play polo for Cal Poly. I felt as if had no true developmental experience prior to this class.However I found that there are so many aspects involved with developing technology that I could relate to. For instance, working with others and approaching certain problems with empathy and understanding is critical for solving problems.

Zack: I am a third year civil engineering student with an interest in sustainability and water resource engineering. I have had experience with international development through working with Engineers Without Borders, but I looked to expand upon my knowledge in this class by working on different type of project than I was familiar with. When I’m not busy engineering, I love to listen to music, travel, and eat donuts.

April: I am a fourth year microbiology major. Prior to taking this course, I had no exposure to development in appropriate technology. This class made me aware of what appropriate technology is and the different impacts it has on a wide range of cultures.

Problem Statement:
According to their website, AidAfrica’s six, brick stove has
already improved the living conditions for people in Uganda by reducing smoke inhalation and improving living standards with cooking efficiency. The organization has made nearly 60,000 stoves already, which have been distributed throughout sub saharan Africa.

Half of the world cooks over open fires. (

AidAfrica is targeting a region where this has become a major health problem. Women and children who spend a lot of the day within the confines of their home are being exposed to constant smoke inhalation. This smoke within each household using open fires can cause lung and eye problems resulting in respiratory diseases and blindness. The risk of the homes catching fire is also higher with open stoves and can result in the devastation of these communities who experience widespread fires.

We are looking to improve upon the current design by implementing an additional “skirt” component that would further minimize the amount of CO2 emissions, reduce the risk of disease attributed to smoke related causes in the region and overall continue to increase the efficiency of the cooking stove. We also want to allow for better cooking efficiency to get more of the population to openly adapt to the idea of using a six brick cook stove. The skirt would not only help further reduce smoke exposure but will also improve overall cooking efficiency.


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Target People:
The group of people we are looking to help are the women and children of Sub Saharan Africa, particularly Uganda, who are being exposed to excess smoke while cooking in the home. Smoke related respiratory disease is the source of over 4 million premature deaths annually ( We are looking to reach these people in Uganda who currently cook with open fires and reduce their smoke inhalation and risk of disease.

Our Design:
How it works:
The skirt acts as a cover that keeps in heat closely surrounding the sides of the pot, rather than having the bottom of the pot be heated and the rest of the heat escaping outward. This will increase the amount of heated surface area on the pot for more efficient cooking, which means less fuel consumption. The skirt will also keep smoke from escaping and channel it through a pipe outside of the home so that minimal smoke will be inhaled in the process of cooking.

Part of our design was inspired by research by Dale Andreatta. While Andreatta’s design focused on improved efficiency, we sought to add our own spin to it with the idea of also channeling the smoke emissions away.

Design Matrix:

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  • Must only use materials readily available in country
  • Working based off of a pre existing design of Six Brick Pot stove so we had to base our design around general pots that would be used when using that technology.
  • Hard to find and ship the right type of Sheet metal we needed for our project

How we worked around the Constraints:

  • We were able to substitute aluminum foil for the sheet metal that was not going to be shipped quick enough to use for our project.
  • We also only worked with metal and did not have time to produce skirts out of clays or other materials readily available in in the country of Uganda. (Although foil could be most likely found there anyway)
  • We also did not have a six brick stove available so we tested to see if our design minimized smoke exhaust over an open fire BBQ pit and the insulation rate by boiling water and taking measurements of how long it took to bring a cup of water to a boil without the skirt and with the skirt.


  • Sheet Metal (Steel, Aluminum)
  • Aluminum Foil
  • Chicken Wire and Cob
  • Natural Clay
  • PVC piping

We ended up only trying metals, but the resources we listed above with out current design of the skirt. One of the main focuses of our project was in turn not the resources we used but rather, the overall design implementation and how efficiently the skirt was able to insulate and minimize smoke being released.


Overall, we made a lot of progress throughout the quarter on our design. We started off with an idea that had not been explored before to create a skirt that would be able to both increase cooking efficiency AND eliminate indoor smoke emissions. Our design went through several stages, from the original one layer steel sheet metal with the “vegetable steamer” top for adjustability, to the two separate sheet layers for better smoke travel, to working with aluminum foil and creating a combined one piece project that was more malleable and able to work with a wider range of pot types. During each stage of the design, we identified a new problem and were able to adjust it to create a new, more effective prototype.

After testing, we found that our design was effective at performing the tasks we set out to do. It was able to improve the efficiency of heating and allow an escape route for smoke emissions. While our design was effective, though, I believe that one area we can use the most improvement on our product is the material it is made of. The two different materials that we worked with were on opposite sides of the spectrum, when we needed something more in-between. The sheet metal was very strong and durable, but proved to be very difficult to hold its shape and adjust to different pot sizes, whereas the aluminum design was very workable to create the perfect design shape to fit any pot, but wasn’t very durable.

In retrospect, there were some things that we could have done differently throughout the quarter to combat this issue. We did have the tendency to limit ourselves in our search for materials to things that we could find locally and that did not cost a significant amount of money. For example, the sheet metal was slightly thicker than we were hoping for, but was available right then and there at home depot and we purchased it anyways because we were eager to begin prototyping. We were able to find a brass sheet metal online that we believed could have been a promising intermediate between the strength of the steel sheet metal and the malleability of the aluminum foil, but unfortunately we did not think about this option until too late and the material couldn’t ship to us until after finals week.

Being in different groups for Lab made it hard to bounce ideas back and forth quickly, and build off each others concepts. We were able to use group chat to help this problem and improve internal group communication. We met up in one section the last couple of shop meetings to help finalize our project and to help everyone get on the same page with the end design of the skirt.

Overall, our group dynamic was good and everyone put in their fair share of work. We all came from different major backgrounds but were able to utilize our skills and work together to come up with a final functioning insulating skirt. We were able to work around time constraints with everyone’s busy schedules.

However, despite these difficulties, we believe our group worked well within our constraints and created an effective prototype. If we had only had more time, we believe that we could definitely continue to improve upon our design with the experience and teamwork dynamic we’ve developed throughout the quarter!

Suggestions we have for future include:

  • Ordering a sheet metal that is about 0.005 of an inch where it would be more durable than foil but less dangerous to the touch.
  • This type of sheet metal would be about the thickness of a beer can so it is able to fit the shape of the pot without warping with the skirts shape when adjusting.
  • Now that we have a design concept it might be beneficial to try natural clay or other material resources.
  • Focus on testing different materials now that the design concept of the skirt is efficient
  • potentially use beer cans to make skirt if thinner sheet metal is hard to locate or is our of budget range.

1st Design:

  • Made out of Steel sheet metal. It was significantly thicker than your average beer can. It was 0.016 inches thick.
  • It was the cleanest looking design because the metal would not wrinkle as much as the aluminum foil we used in our other prototypes.
  • However, the edges were too sharp and the sides did not hold a cylindrical shape very well. It was not very adjustable.
  • The seal under the lip of the pot was not effective either, and connected poorly.
  • The bottom of the design had no sealed connection either to keep smoke in from leaking out from underneath.

2nd Design:

  • The concept of the second design worked a lot better with substitution of the steel sheet metal for aluminum foil.
  • We were able to fit the adjustability problem by using malleable foil with no sharp exposed edges.
  • The smoke was able to enter and exit properly with the addition of connecting the layers at the bottom better by using one piece of material and bending it into shape.
  • Problems we faced with this second prototype included the fact that it was overly malleable and did not hold its shape very well post testing.
  • The pins did not sufficiently enclose the prototype
  • The hole was too large which allowed excess smoke to escape

Changes we made for our 3rd and Final Design:

  • Smaller hole and addition of smoke stack to effectively draw the smoke upwards and out.
  • Made the Final design entirely out of aluminum foil with the exception of the chicken wire, foil wrapped pieces which acted as spacers between the inner and outer layers.
  • We also extended the length and layer count from 16 layers to 20 aluminum foil layers in order to enhance the adjustability aspect.

Our Documented Progress:

  • We have began to experiment with bending sheet metal into a shape that will fit stove pot
  • Tested different materials (aluminum, galvanized and non-galvanized steel) and thicknesses for formability
  • Created “vegetable steamer” style design to allow easier folding

Next Steps:

  • Create full sheet metal prototype
  • Come up with plan for how to attach smoke escape valve to our design
  • Experiment with design on different materials


  • Establish appropriate materials and general design for prototype
  • Use paper model to visualize possible design ideas
  • Research current models
  • Take parts we like and build off what has already been done


  • We bought aluminum to start the first model of our skirt design.
  • We first made a aluminum foil design to help visualize how the aluminum sheet metal will be bent and cut
  • After sizing the pot we cut sheet metal and bent it into its first design, shown below
  • We are going to try to use a pin like design to create an adjustability feature to the skirt allowing for it to fit different size pots
  • Our next step is to attach the two components together, and test the prototype

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  • When we were deciding on material we initially thought that an steel sheet would be malleable enough to bend and hold in place.

  • We bent the metal and cut it to form our initial two later design but it had dangerously sharp edges and was hard to adjust.

  • We decided we needed to work with a larger pot to base our skirt size off of because the one we first had was way to small when realistically looking at the size pots the people in Uganda regularly use.

  • We found and order brass that would insulate well and was 0.005″ (vs. 0.016″) which would allow for easy sculpting and provide a stronger hold without cutting the user.

  • We found that the bottom should be sealed and the metal should be one piece bent into two layers that would bend at the bottom to produce this flat bottom seal.

  • PROBLEM: The metal we initially ordered from the home depot that was the correct thickness was not going to arrive in time.

  • SOLUTION: We are going to layer and flatten aluminum foil with roller in the shop to get a malleable yet some what durable metal to work with. Hopefully we can get it sturdy enough to where it will hold shape and not tear as easily as regular aluminum foil


  • We flattened and layered aluminum foil to create a new material to build with

  • Bent the new material into new one piece design

  • Created aluminum spacers to keep two layers at a set distance apart from each other

  • Cut smoke escape hole out of outer layer


  • Tested design on open flame to see if smoke would escape out of the hole we hoped

  • Overall, smoke behaved how we expected it to!

  • There was some smoke leakage out of the top, but this can be solved by creating a better seal

  • Also, we will need to create a stack for smoke to rise out of side hole


  • Reconstructed design with thicker aluminum foil and 5 extra layers for more durability

  • Came up with new more effective spacer design using wire and foil to hold place from both inside and outside

  • Tested for efficiency by boiling water and timing in a pot with and without skirt


Above are two videos of our testing of the insulating skirt. First we tested our prototype over an open fire to see if the smoke would travel the way we wanted and was contained. Overall, despite the smoke coming out from the unsealed flame under the pot, the smoke that did get captured in our skirt was able to successfully exit through the hole we made in our outer layer.

We also tested the insulation rate by boiling a 1 cup of water. One trial with the skirt and one trial without it.

We saw that the insulating skirt was able to heat the water to a boil in 2 minutes and seven seconds and the trial without the use of the skirt brought the water to a boil in 4 minutes and 7 seconds, successfully proving that our skirt had efficient insulation capabilities.