I keep my apartment at about 55F in the winter. Does this increase my basal metabolism in any significant way?
Finland is populated almost entirely by deplorable alcoholics.
The unofficial national drink of Finland is table sugar and water fermented in, and then drunk from, a plastic bucket.
If you actually feel the cold then yes. When it's cold you need to either conserve heat or generate more heat. You generate more heat by burning calories. You can conserve heat with fat and muscle and blankets, sweaters, etc.
Conserving heat doesn't raise metabolism generating it does. Put that shit down to 55 and wear normal clothes.