Using reflectix and vinyl we created a cover for the top of the fridge. This is a super easy and cheap project that improves fridge efficiency significantly . Ventrally we will do the same thing behind the kitchen utensil holder on the front of the fridge. If you slide your hand between the reflectix and the top of the fridge it feels very cold. However on top of the vinyl covered reflectix it is room temperature.
This is a link to the the insulation. We have used it to make ducting for our window ac unit to vent it down through a top hatch into the salon. We are gradually insulating the cabin walls and overhead with it as we do projects that expose those areas as well as the above project.
Reflectix BP24025 24-Inch by 25-Feet Bubble Pack Insulation
we used hvac tape to secure the vinyl to it.