Every time you open a walk-in refrigerator or freezer door you dramatically impact the interior temperature of your unit. The interior air escapes and mixes with the interior air before you even take your first step. As a result, your equipment works harder (and uses more power) with every trip to the cooler. Consider purchasing strip curtain swing doors which are made specifically for units with swing doors. These curtains sit just inside the door and help maintain the cool, interior temperature every time you enter.