Start by turning off your fridge. You do this by turning the knob by the light to 0, or by unplugging the fridge.
Make suds in a bucket with green soap (or a scoop of baking soda and some lemon juice). Using less hot water and properly dosing your detergent is the most sustainable. Use about 1 tablespoon of green soap per litre of water or about 2 tablespoons of baking soda per litre of water.
Remove all food from your fridge. Put the food temporarily in a grocery crate or box. If it's colder than 10°C outside, it's fine to put the crate or box outside to keep your food cold. Is it warmer outside? Then it's wise to put cooling elements with your food so it doesn't heat up too much. Place a blanket or bath towel on top of your crate of food to keep your food cooler.
Pull all drawers, shelves and racks out of the fridge and clean them in your bucket of soapy water with a soft brush or cloth. Let these items drain and dry them well with a tea towel.
Take a clean cloth and thoroughly clean the rubbers of your doors. Immediately check whether the rubbers still allow your door to close properly. If not, consider buying new rubbers. A door that closes properly ensures that the fridge uses less energy.
Wipe the inside and door of your fridge well with your cloth. Clean the condensation drain of your fridge especially well. Dirt can remain here, preventing the condensation from draining away properly. Is the drain blocked? Clean it with a cotton swab or cloth over the back of a teaspoon (an old toothbrush often works well too). Let the fridge air dry or use a tea towel to dry it. This prevents a lot of moisture from staying in your fridge, which costs more energy to cool.
If you have a freestanding fridge, pull it off the wall. Carefully vacuum the dust off the grill with a brush and then clean with your cloth. A dusty grill prevents your fridge from getting rid of its heat properly and increases your appliance's energy consumption. Put your fridge back, but make sure there is enough space between the wall and your fridge for the cooling to work optimally.
Put your drawers, shelves and racks back in your fridge and put your food back in the appliance. Extra tip: immediately check the best-before date of your food. Are products nearing their expiry date? Then put them at the front to be used up immediately. Is it spoiled? Get rid of it!
Turn your fridge back on and close the door.
Bonus tip: check the temperature of your fridge after a few hours. Ideally, the temperature in your fridge should be around 4°C. This is how food stays good the longest.