Don’t Waste… Insulate

By Will Townley Porter and Elliot Mairet
Intermediate Category (Grades 9-10)
Innovation | Environment

Polyester is one of the most wasted fabrics in the world, making up approximately 40% of all clothing waste. Many textiles are ending up in landfills due to the uprise in fast fashion. At this rate, by 2050, 25% of all carbon emissions will come from wasted clothing that takes years to decompose. Only 10% of the clothing donated actually finds its way to a second-hand market, while the other 90% goes to the landfill. If only there was a way to repurpose some of that wasted fabric and recycle it into something every home needs, insulation! Our experiment is to test polyester as insulation and compare it to fibreglass. Our goal is to divert and repurpose polyester waste into ground-up insulation, essentially creating a fleece for your home using commercial, retail and consumer polyester waste. Polyester has been tested on many levels as a clothing insulator and has shown to produce premium quality insulation ratings. Polyester is also itch-free, extremely durable, not toxic and flexible making it a very intriguing material for home insulation that could benefit the environment.

Is ground-up polyester a low-cost insulation solution that saves the environment and is comparable to fibreglass?

If we repurpose polyester as an insulator, then it will perform equally or better than fibreglass. We think this because polyester has been tested on multiple levels and has shown and demonstrated that it has premium insulating properties that can compete with fibreglass.


  • Pure premium high-loft polyester
  • Fibreglass insulation 15 cm W x 37 cm D x 117 cm L
  • 2 x 54 oz (7 cups) plastic containers with 6 cups of around 100 (℃) water
  • 3 x thermometers
  • Tape
  • 3 x cardboard boxes 16” W x 12” D x 12” L (40.64 cm x 30.48cm x 30.48cm)
  • Nail, the width of the thermometer
  • Styrofoam the size of the base of the containers


  1. To eliminate heat sink and provide a solid base for the containers, place a styrofoam piece in the middle of both of the cardboard boxes.
  2. Puncture a hole with the nail the width of the thermometers into the container lids.
  3. Place both containers on styrofoam.
  4. Fill the first box with pure premium high-loft polyester surrounding the styrofoam and
  5. the container.
  6. Fill the second box with fibreglass insulation surrounding the styrofoam and container.
  7. Fill containers with 6 cups of 100 (℃) water.
  8. Place thermometers into containers.
  9. Document room temperature.
  10. Document the temperature of both containers of water.
  11. Cover container with polyester.
  12. Leave for one hour.
  13. Document the temperature of both containers of water.
  14. Repeat steps 6 to 12, 6 times in a row.
  15. Compare data.


Controlled variables:
Initial water temperature, the water bottles, the environment, the length of the experiment, the box, the styrofoam and the nail that punctured the holes in the container lid.

Independent variables: The insulation

Dependent variables: The end water temperature

Technically our hypothesis was incorrect, but practically speaking the performance difference was insignificant. We proved that polyester can compete with fibreglass as an insulator. The polyester dropped an average of approximately 4.46 °C an hour, while fibreglass dropped at an average of 4.16 ℃ per hour. Based on our evidence, generic polyester from a fabric store that wasn’t designed to insulate can compete with scientific fibreglass insulation very well. On top of polyesters’ great insulation performance, it was much easier to handle than fibreglass and may make for a simpler installation process. This begs the question, how much better could polyester get as an insulator if it was designed and manufactured at the level of fibreglass? Through this process, we have learned about the factors that make up a great insulator and about the ways to repurpose wasted fabrics and eliminate fabric pollution. This experiment was very fair, as we made sure that all of our controlled variables were kept the same over the length of the experiment. We also made sure that our data was as accurate as possible by setting alarms for the exact time we needed to check the water temperatures. One way we could have made our experiment more accurate was starting with the same water temperature in each container. The difference in the water temperatures of the containers was 0.5 ℃. This was a very small difference in temperature so it wouldn’t have affected the results in the end, as we were testing the decrease of the water temperature every hour for a long period of time. The next step would be to actually convert generic polyester fabric into a high-loft fill to form realistic insulation and run the experiment again.

Now we are wondering if we can actually make polyester insulation into a viable option as realistic home insulation. We are also wondering what further steps in different directions we could take with the same idea of repurposing used polyester to create different alternatives to everyday problems.

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