How do you know its time to replace your windows?

As the owner of a window installation company, I get this question a lot from people that have thought about replacing their windows, but just dont know enough to make that sort of commitment.  The first thing I would tell any one in the Houston area is, start by taking a closer look at your windows.  Start inside.  Look at the window stools.  Do you see debris like dust and small bugs?  Is the paint cracking?  Is the stool sweling in certain areas?  How about the drywall?  What condition is the caulk in?  If the answer is not a good one, then these are signs that the window is no longer doing its job.  

Now take a look at the outside.  Is the caulk in good condition?  this is even more important outside given that cracks will invite small bugs and your walls will provide a nice home for them.  Also, look at the condition of the glazing beads around your glass.  These are small plastic strips that help keep the glass in place, but on older windows they tend to be falling apart.  

But none of these issues have anything to do with the window itself.  Up until about 2010 almost all windows in the Houston area had aluminum frames.  The reason being that they were durable, strong for their weight and corrosion resistant. The problem is that they also transfer heat easily.  And in Texas, thats a problem.  These days, aluminum framed windows will be thermally broken which helps with the insulative characteristics of alumunum framed windows, but 15+ years ago, it was rare to have that feature.  Then came along double paned windows, argon gas and more efficient Low-E coatings which all help with the overall efficiency of modern windows.  Then the aluminum frame was replaced with vinyl, which is a much better insulator.  All of this adds up to lower electric bills, quieter interior, fewer bugs, dust and an overall more comfortable house.  

 I tell people, the debate over whether to replace your windows or not is a lot like debating replacing an older car.  If all your car needs is new brakes or tires, its hardly worth it, but when your car needs new brakes and tires and gets 15 miles to the gallon, doesnt have a infotainment screen, and goes 0-60 in 10 seconds, then it starts to make more sense to replace it.  All too many people dont pay attention to the signs.