Excessive dust buildup will make the refrigerator work harder and run longer. Let foods cool before placing in refrigerator unless the recipe specifies otherwise. Warm food will cause your refrigerator to run more. Thaw frozen foods in the refrigerator rather than on a counter top. This is safer plus frozen items will help cool the refrigerator as they defrost and may help reduce its running time .
Freezers work better fully loaded.
The foil may block heat or air circulation reducing oven temperature as much as 50 degrees. It may also interfere with even browning. Cooking with tops on pots will bring liquids to a boil more quickly and will allow continued cooking at lower temperature settings. Also, trapped steam in the pot will cook food faster. This reduces energy use and heat in the kitchen.