Step 1: Simple Overview
Step 2: Gather Supplies
You can use 2 liter bottles or individual water bottles.
Step 3: Freezing Weather
Place outside and let sit until completely frozen.
Step 4: Place in Fridge
In my fridge the top is coldest, so I place my bottles at the bottom.
The idea behind placing the bottles in the fridge, is that the frozen bottles will reduce the temperature of the fridge without making the fridge work to reduce temperature.
This is a simple but effective plan, it won't save you thousands of dollars , but it can't hurt.