Panes

• Single-pane windows have only one layer of glass. Double-pane windows have two layers of glass with a space between them filled with a gas.
  
  

Cost

• Single-pane windows are the cheapest type you can get. Double-pane windows will cost more up front but can save money over time.
  
  

Noise

• Single-pane windows transmit sound easily, so outside noise is easier to hear. Double-pane windows are naturally more resistant to noise transmission because of the layer of gas between the layers of glass.
  
  

Heating and Cooling

• Single-pane windows transmit outside heat and cold more easily, driving up the heating and cooling costs of a home. Double-pane windows provide a thermal barrier with the gas trapped between the layers of glass.
  
  

Types

• Single- and double-pane windows come in all types--horizontal, single and double hung, shuttered, and wood, vinyl or aluminum.