• A lot of heat is lost through windows in the winter.Pattern window image by Lena Nikolaeva from Fotolia.com
  
  In very cold winter climates, windows are one of the prime culprits for heat loss. Even good, thermopane windows, while helping to heat the house with sunlight during the day, will lose substantial amounts of heat at night if they aren't properly covered. A variety of energy saving window treatments will help to alleviate this problem.
  
  

Plastic

• Simply covering windows with plastic will help to keep a lot of heat in. This method will make more of a difference with leaky old single-paned windows than with newer windows that are already fairly efficient. You can use any plastic and simply tape it around the frame with packing tape, or you can get a nicer look and a clearer view out the window by using plastic that has been specially designed for this purpose. You can attach this purpose-made plastic to the window frame with double sided tape, and then run a hair dryer over it to stretch and tighten the plastic, making it nearly invisible.
  
  

Quilted Curtains

• Because most of the heat loss through windows occurs at night, it makes sense to have heavy, insulated curtains to hang in front of the windows at night. The best curtains for this purpose are specially made for purposes of insulation, and have insulating material built in between the front material and the lining. Some curtains hang from a rod and are pulled open and shut like normal curtains. Others are made even more effective by attaching velcro all around their edges and to the window frame. This way, the curtain can be sealed to the window at night and radically reduce the drafts that come in through the window. In the morning, the velcro curtain can be easily pulled away from the window frame.
  
  

Rigid Foam

• An effective method for extremely cold areas, or for very leaky windows, is to cut pieces of 2 inch thick rigid foam to fit tightly into the window frame. The foam can be used to plug the windows at night, and then taken out and stored nearby during the daytime. For a more attractive look, cloth coverings like pillowcases can be sewn to fit around the foam pieces. This method of window insulation is somewhat labor intensive to do every morning and evening, but if you are living in an area that gets to 40 or 50 below, as it frequently does in parts of Canada, the energy savings over many nights of winter are well worth the effort.