This is a test of commonsense. Complete the next sentence:

How to efficiently heat a room
Replace old or damaged weatherstripping on the doors and windows.
Buy a new roll of weatherstripping at your local hardware store. Install it in the gaps around any doors and windows in the room to prevent heat from escaping and cold air from coming in.
Just pull off the old or damaged weatherstripping and apply the new roll using the adhesive that comes on the strips. Raise the door thresholds if they're adjustable.