Thanks for your question, and thanks for giving such a detailed outline of your proposal!
We don’t know the exact number of households with fridges, but you can assume the majority on Cape York will. The Census data (found in Tips for Getting Started: Explore the Community Context) will be able to shape the number of dwellings on Cape York, but it’s important to keep in mind that the population of Cape York fluctuates throughout the year and the Census was redone earlier this year (with results yet to be announced) so there is likely to be a difference in the population. You can account for this by framing your proposal in another way, such as outlining how many people are needed for one installation and seminar and how long it will take. From there, your solution can be scaled up if necessary.
In terms of your proposal, I’d also recommend thinking about whether the savings generated by this design outweigh the potential negatives.
For example, neoprene as a material is notoriously bad for the environment in both its production and end of life – will the energy savings generated by applying this to a fridge outweigh the environmental impact of the creation, transportation and disposal of the neoprene? Will the financial cost of implementing this solution (eg. sourcing neoprene, employee wages for installation and running seminars etc) be compensated by the energy savings from making fridges more energy efficient?
There are likely going to be trade-offs in your final design choice which you will need to justify in your report, but I’d encourage you to assess your design against a broad criteria to ensure that your solution is appropriate for the Cape York context. I recommend taking a look in the Participant Resources tab at the Design Considerations and Key Development Concept pages which outline some considerations to factor into your design choice.
Hope this helps, and feel free to reach out with any further questions!