Which method of heat transfer can occur in empty space?.

Heat radiation.

This is the form of heat transfer that doesn’t need a medium to transfer through.

That’s how heat from the sun gets to earth, even though empty space is very cold.

Radiation is a heat transfer process that does not depend upon the contact between the heat source

Some reasons why .
*Air flow is being restricted between the furnace to the registers.
*Ductwork is not the right size or hasn't been sealed properly.
*Your furnace or air conditioning system isn't the right size for your home.
*Thermostat is only reading the temperature of the floor that is being heated/cooled.