Should You Upgrade Your Old Windows to More Energy Efficient Windows?

With the price of heating and cooling rising almost daily, I started looking at my old windows and wondering if it wouldn't be worth it to replace them with newer, more energy efficient ones. I had read about Energy Star ratings and how they rate the energy efficiency of building materials and appliances so I started to research energy efficiency to see if it would be a good investment to install more efficient windows in our townhouse. I wanted to see if they would pay for themselves and how long that payback period would be.

After a little searching I found a simple calculation that will yield your payback period for installing new energy efficient windows.

According to Energy Star, who rates the energy efficiency of everything from appliances to building materials: An average household spends over 40 percent of its annual energy budget on heating and cooling costs Energy Star says that you could reduce those bills by up to 15 percent with better windows.

We can break that claim down into a simple formula:

(Your average monthly energy bill (if you have gas and electric just add them together) X 40% ) X 15% = projected savings per month. Divide this number into the cost of upgrading your windows and you have how many months it would take to recoup your investment.

To make a long story short, projected savings are 6% of your energy bill.

For our house the numbers look something like this:

Average month's electric bill: $141.20 times 6% = avg energy savings per month $8.472

The cost to replace 6 windows with Energy Star windows: Approx $330 (at the low end) per window X 6 windows = $1980 (if you have special tax rebates available in your area subtract those from your total).

Next I figured out the projected payback period:

$1980 / $8.472 = 233 months or 19.5 years

The numbers make it hardly seem worthwhile for me to do this, so I decided that if I want to save money by saving energy there may be other (hopefully better) ways for me to do it. I calculated this based on costs including installing the windows myself. If I were to pay to have them installed by a window company the cost would be higher and the payback period proportionally longer. While it doesn't seem worth it for me to do this, if you have more tax rebates available to you where you live, and/or a higher energy bill, it may be worthwhile for you. Just remember, before making any major purchase, first: DO THE MATH!