Unblock heat flows by moving furniture away from registers
If your desk, bookcase or piles of boxes are right in front of a register or radiator, they will get very warm, but the heat can’t travel into the room, where the people are. Your heating (or cooling) system has to work harder to keep you comfortable.
Move furniture and other obstructions so there are several inches between them and registers or radiators. Consider moving excess materials to a storage room.