Now take a trip to the furnace with a brand new filter. You should buy a filter that matches the specifications of your furnace exactly. The old filter should be somewhere near the air inlet, although that varies depending on the furnace. Remove the old, dusty filter and slide in the new filter, paying attention to the markings on the filter that point in the direction of airflow. Read the packaging material as to how many months your filter should last. If it says a month, change it again in a month.

Check out all your windows, especially those in areas you’ll be spending a lot of time in. Feel along the edges for any breezes or cool air coming through. Check the window panes for condensation or frost on the inside. Check for breezes around exterior doors as well.

Windows that form condensate, form frost over, or around which you can feel a breeze need to be treated with weatherizing plastic. You can buy kits with enough plastic per box for a couple of windows. When you open the package, there should be some clear cellophane in a single sheet and some double-sided tape.

Tape around the window with double-sided tape and apply the cellophane as tightly as possible over the window. Trim off excess and use a hairdryer to further tighten the cellophane so there are no wrinkles or defects. Repeat for all windows you need.

With doors that leak beneath them, purchase or make a cloth tube filled with plastic pellets. The tubes should have a diameter of around 4-5 inches. Set them up against the door to keep the draft out.