Windows are one of the most poorly insulated parts of an apartment, but upgrading the glass isn't an option when you rent. Fortunately, you do still have options that can lower your energy usage while keeping your apartment cooler in summer and warmer in the winter.
Cut the Drafts
If your apartment windows are letting in drafts, chances are they aren't sealed properly. To check for drafts, turn off your heating and cooling system and close the window.