Cup Insulator


Last week, Mr. Pray’s and Ms. Mona’s Science class went to the design lab together to work on a design challenge. Our Challenge was: our teachers would usually get a cup of coffee from the lounge to enjoy in the classroom. However, their coffee would turn cold by the time they reached their classrooms. So, we had to design a cup insulator to keep our teacher’s drinks warm.

The criteria that we had to work within:

  1. The insulator must fit the teachers’ cups and not fall off;
  2. It must reduce the heat loss of liquid inside
  3. It must look good-something you would buy in a store
  4. It should not interfere with drinking the liquid
  5. It should be reusable
  6. Must be removable

My partner on this project was Jen. I am so glad to work with Jen again after we successfully made a cardboard arcade game together in Design class. After looking at the materials available, we decided to make two layers of the insulator– one layer of foam, one layer of felt. We chose these two materials because they were one of the thickest materials, and are good insulators. We would put the layer of felt on the outside, since it looked nice. We would also decorate it with buttons, and a ribbon on the outside to make sure the insulator did not slip off.


We had three lessons to create and test our insulators, it was quite a time crunch! Jen and I managed to finish in the nick of time. We mostly followed our original plan, but we did not put a ribbon on because the two layers were already very secured. We also put a handle on top, and added two straps to secure the cup’s cover, because the steam from the water may push it off. One big change we made to our design was not gluing the foam and felt insulators together. This was mainly due to the fact that the two insulators were designed differently. One was to be put on from the front, one to be put over the cup’s handle. So, they could not be glued together, but we managed to come up with a solution to remedy the situation: the foam insulator would be shorter so that the teachers did not have to take it off while drinking the liquid, and it would continue to partially insulate the drink.

Last lesson, we tested our insulator, using a software called “Logger pro”. We linked the thermometer to the computer, and the temperatures the thermometer recorded were put into a graph. In all, I think we did a good job because from the temperature readings, the heat loss of the drink was reduced to some extent. Also, our insulator looks nice. The only major problem was that our straps fell off. This is because the steam from the liquid melted the hot glue, which ultimately also made our lid fall off.



The heat loss of a hot liquid in a mug is reduced with an insulator.


I can support this from various data I collected, including the thermometer readings: The temperature from 0 minutes was: 88.1º ; the temperature at 5 minutes was: 81.6º; the temperature at 10 minutes was: 76.6º. So in all, out heat loss was 11.5º. I also realized that the cover of the lid was very wet. Jen and I are insure whether this was because of the fact that the water spilled when we put the thermometer in or because of water vapor. Additionally, one of our straps on our cover fell off because the hot glue securing it melted due to the extreme temperatures of the hot water.

However, throughout the experiment, our insulator did not get any warmer but mostly just felt like normal cloth. It did not heat up and we could not feel any heat from the liquid.


Based on our testing of the insulator, the heat loss of a hot liquid can be reduced with an insulator.

The reason that the teacher’s hot drink would lose heat is because of conduction, convection, radiation, and evaporation.

Conduction happens within a medium and in this case it happened within the cup’s inner and outer walls. The wall layer of the cup was heated and received heat from the hot liquid, and it conducted this heat into the outer layer of the cup.

Convection is when hot air rise higher into the atmosphere and cold gases take its place. This happens at the brim of the cup when the heat from the liquid rises up, since there is nothing blocking, and making the liquid colder.

Radiation is when heat is sent away from the object producing it. In the case of the experiment of the hot liquid and the cup, radiation happens after the heat of the liquid reaches the outer layer of the cup. With nothing else for it to conduct the heat to, it radiates the heat out, causing it to feel warm when we touch the cup, or in extreme cases, put our hands near it.

Evaporation is when water changes forms into water vapor. During this experiment, because the liquid is hot, some of the water particles that have more energy may evaporate, leaving us with water particles with not as much energy. This is also a subtle form of heat loss.

In our cup insulator design, and throughout our test, we managed to reduce heat loss. By wrapping a layer of foam and felt around the side of the cup and on the bottom, we managed to prevent radiation. Even though we did not block conduction of the liquid’s heat into the outer layer of the mug and the layer of foam and felt, foam and felt were not good conductors, and were thermal insulators, the heat stayed mostly trapped between that layer.

Jen and I also managed to partially stop Convection and evaporation by making a cap, although it got pretty wet in the end. The felt cap stopped some of the hot air from passing through and kept it in. It also blocked some of the water vapor from escaping which meant that the more hot water was still inside the cup. We can see this because our cap was really wet in the end and it soaked through 3 paper towels. Of course, this might also be the case that the water was already full to the brim and it spilled when we put in the thermometer.

All of this is true because of the results of our insulator testing listed above, and the graph pf the temperature change of the water below. The control group’s heat loss was 20.9º over 10 minutes, and the heat loss for the hot drink with the cup insulator was 11.9º over 10 minutes. The heat loss was reduced by 44%, which is considered quite a big leap.

So in all, we can conclude that Jen and I’s insulator design worked well, and that foam and felt good insulators. However, I am not entirely sure whether foam is the better insulator or felt, as they were not tested individually; or whether individually foam still works as an insulator; or whether they were only good insulators because they worked together and had the advantage of having two layers.

Two things to think about:

What I was proud of

I was really proud of and really enjoyed  collaborating and building each others ideas Jen successfully again, and make another wonderful creation together. I was especially proud that we managed to improvise on certain measurements and plans, even when our original plan did not work out as expected. Especially since we couldn’t glue the two insulators together, due to the way we structured them. I also think that our insulator looks really nice appearance wise, something I would buy in a shop. It had bright background colors with buttons to add the touch. We also other set criteria such as the insulator being reusable, and it not interfering with drinking the drink in the cup itself.


There were several limitations, the largest being that there was a time limit. Our paper prototype was not entirely successful, however we did not have time to make another one, which affected our future measurements, and made us a bit doubtful when we started cutting out the real materials.The material was limited even though Jen and I made the best of it. We also had a limit that the insulator had to be reusable- and could be taken off; which makes the design harder as we need to give more thoughts to the removing process, and how to deal with the handle of the mug. If the insulator did not have to be reusable and we did not have to take it off the mug, I would’ve just glued everything straight on the mugwithout a second thought.


In all, I really enjoyed this Design challenge, and look forward to more challenges in the future! I also appreciated the change in surroundings, and the people that we sit with, since the other Science class was there too.


1 -2 (left to right ) Jen and I’s Design paper. We did not do prototype two because we only had three lessons to complete the cup insulator and 1 partner. Left bottom up and down, our insulator on a mug  Right bottom. The different parts of our insulator. Most Bottom picture: Graph measurements of temperature of hot liquid over 10 minutes. ( there was a drop because our thermometer fell out)