You may not realize this, but Susan is saving energy on her energy bill right now without really trying. Susan is making dinner.

The water that she's boiling is in a pot with the lid on top, helping keep more heat in and boil the water faster. This saves her time and energy.

She's also chosen to match the pot to the same-sized burner. This ensures that all of the heat generated by the burner goes into cooking her food, not heating the room.

By using the microwave instead of the oven for her potatoes, she's saving even more energy. And because she's thawing tomorrow's main course in the refrigerator instead of under running water, she's going to be saving all night long as well.