A. Yes and no. 

Double paned windows are manufactured as a unit: a spacer surrounded by two glass panes. The space in-between is carefully sealed and filled with an insulating gas such as Argon. 

The intention of the gas filled spacer is to help insulate the panes and provide increased energy-efficiency for your home. 

Once a pane is cracked or broken, the gas has already escaped, causing the window to lose its insulating value. Other insulating benefits are lost as well, including: heat absorption, UV sunlight protection and soundproofing.

This means that the entire window section should be replaced, but not the entire unit. For example, if your unit is a double hung window unit, then it has two parts. The upper glass section, and the lower glass section. 

Just the section where the break occurred needs replacement. 

This entails replacing both panes and re-sealing the window. Fortunately, your repair bill will be less expensive than replacing the entire unit. 

If your windows are older, and you’ve noticed your energy bills increasing, you may want to invest in new, energy-efficient window. These type windows can save you several hundred dollars a year on your utility bills.