Unfortunately, windows become less efficient after years of normal usage. Even if there is nothing technically wrong with your window fixtures, they probably aren't as efficient or insulating as they were when they were first installed. You definitely need to maintain your windows to keep them as efficient as possible. You might also be able to do a few simple things to improve the insulation of your windows. This article explains how you can improve your window efficiency by adding window film. Window films installation is simple, and these films are useful in cold climates, too.
The first thing you need to know about window films is that they are actually useful in cold climates as well. Of course, most people are familiar with tinted window films. These are great for reducing heat transfer and solar absorption. That is, your interior won't be as dramatically affected by the sun rays, making it easier to keep your home at the perfect temperature. Some people don't like the fact that tinted films can block so much light and make their rooms darker. If you value brightness, tinted films aren't for you, but clear films can still be useful.
Clear films can add insulation to your glass. It obviously won't make a dramatic difference, but you will probably notice the improvement. That is, your glass won't be so cold to the touch. This can translate to reduced heat loss and less reliance on your HVAC system. Even this small improvement, could reduce your utility bills if you are able to accordingly adjust your thermostat.
Window films are a very affordable way to make your windows more efficient, especially since you can install them yourself. Most window films come in a basic package that includes almost everything you need to apply the film to glass. You will need to supply your own utility knife, but the kit includes the film, liquid adhesive solution and squeegee. Clean your windows, then apply the liquid adhesive to the glass. You press the film onto the glass and use the squeegee to press out any bubbles. Get the corner tight against the window sash, and then use the utility blade to trim the excess film. Wipe any liquid off of the your window sashes, and double check for bubbles in the film before it dries.
As you can see, this is a simple project, but one that is worth it if your old windows have poor insulation.