This is a tough question to answer without more information. I will give you a more general answer based on my experimentation with energy modeling software that accurately measures heat flow and energy costs based on the Florida market. For the answer I will model a 2,000 square foot home with approximately 15% of that area being single pane clear glass windows. Let’s replace those windows with a quality double pane, Low-E window. Low-E is a treatment film placed between the two panes of glass that reflects a percentage of the sun’s thermal energy, reducing your air conditioning load. The cost savings based on average cooling hours and utility costs will be approximately 15%. Let’s estimate your annual cooling cost to be $2,500. 15% savings would be $375 per year. Let’s estimate your window replacement cost at $3,500. All these numbers are for example only. You divide the cost to cool by the projected savings and you will get 9.33 years. Using these numbers it will take you over 9 years to recover your cost. Most businesses will not make upgrades that take longer than 3 years to recover. Be careful when listening to a sales persons claims, they are trying to sell you something. You can post a question here with specifics and I will give you a prompt response. My final thought, you may choose to replace your windows for many reasons, if energy savings is one of many reasons fine. If energy savings is the only reason, generally there will be other energy savings improvements that will give you more bang for your buck.
Posted in: Conservation Questions