Moist air holds more energy at a given temperature than dry air.Warmer air means more energy flux when the air's exchanged.
but more importantly, things have different thermal densities - a liter of water will 'hold' more cold than will a liter of most dried items.
Of course this isn't really what you meant. This a cumulative time, so if you leave the door open for an hour three days in a row you're going to have to throw out a lot of food. This is a couple of hours for most potentially hazardous foods as indicated in the answer to the linked question.
In terms of food safety you can leave the door open for the same amount of time that your food can safely sit on the counter when taken out of the fridge.