Skip to main content

«  View All Posts

Window Replacements

How Much Can Replacement Windows Save On My Energy Costs?

February 20th, 2013 | 6 min. read

How Much Can Replacement Windows Save On My Energy Costs?

Print/Save as PDF

It’s a very fair question to ask how much you can expect to save on your energy bill by replacing your windows. After all, the benefits must necessarily outweigh the cost, or it wouldn’t be worth the investment. Well, there are many factors are involved in determining the energy savings you will see when you upgrade the old windows in your home to energy-efficient windows.  I have been in this business for 18 years and have seen savings vary, but everyone saves a significant amount.  Out of the last 4,000 window jobs that I have been involved with, I have had clients tell me they have saved 26%, 33%, 52%, and so on.


There is no doubt that you will save money on your utility bill by installing insulated replacement windows.  But exactly how much is a very tricky question.  Let’s focus on some of the key factors involved that will change your energy bills.



  • U values and Solar Heat Gain Coefficient ratings of the window (see the National Fenestration Rating Council website)
  • Material used in the frames of the windows
  • Window installation methods
Most of the savings on heating and cooling will depend on the difference between the energy-efficient characteristics of your old and new windows. For example, let’s say your home has old aluminum single-pane windows, as do many in the San Antonio area.  Your current windows do not insulate your home well, so if you upgrade to gas-filled, double-pane windows with non-conductive frames, you will see very large utility savings.  However, if you upgrade when you already have double-pane vinyl windows, you will still see savings, but not as drastic.

Architectural and Landscaping Considerations

  • Amount and size of windows (total square feet of glass in the entire home)
  • Placement of windows (i.e. west or south walls)
  • Shade around the home from trees or other buildings
  • Glass that is covered by a patio or 36” overhangs


How light and heat enter your home can determine how much you can save on utilities by upgrading your windows.  For example, if you have no trees to block the sun and many large windows on the south side of your home, with no eaves or overhangs, energy efficient windows will reduce your cooling costs in the summer significantly.  If you have windows on the west side where the setting sun shines into your dining room at the end of the day, upgrading your windows will make dinner much more comfortable. In comparison, if you have a porch or deck with 36” overhangs or a patio cover, which protect from the sun, replacement windows will have less of an impact.

I have had clients brag about rooms in their home that they can actually enjoy using again after getting new windows. New windows that block UV rays can also keep your carpet, floors, and pictures from fading out in rooms that get the most light.


Your Utility Habits and Other Factors:

  • Where you set your thermostat
  • Age of the air conditioning unit in the home
  • Amount and type of insulation in your home
How do you use heating and cooling in your home?  If you like to keep your home a much higher or lower temperature than the outside world, high-end windows will help you do this at a lower cost.  With new windows, your air conditioner will run less, which will add more life expectancy to your system.


How To Calculate Energy Savings From Replacement Windows? 

Calculating the energy savings from replacement windows involves several factors, including the type of window, the size of the window, the climate where you live, and the energy costs in your area. Here's a general formula you can use to estimate your potential energy savings:

  1. Determine your current energy costs: Look at your energy bills over the past year to determine your average monthly or annual energy costs.

  2. Estimate your new energy costs: Use an online energy savings calculator or consult with a window expert to estimate the potential energy savings you could achieve by upgrading to energy-efficient windows.

  3. Calculate the difference: Subtract your estimated new energy costs from your current energy costs to determine your potential energy savings.


For a more detailed calculation, you can use the following formula:

  1. Determine your current U-factor and Solar Heat Gain Coefficient (SHGC) ratings for your existing windows. These ratings can be found on the window label or by contacting the manufacturer.

  2. Calculate the U-factor and SHGC ratings for the new windows you're considering.

  3. Use a window energy performance calculator or consult with a window expert to estimate the energy savings you could achieve with the new windows based on your specific climate and energy costs.

  4. Calculate the difference in energy costs between your current windows and the new windows to determine your potential energy savings.

It's important to note that these calculations are estimates and the actual energy savings you achieve may vary based on several factors. It's recommended to consult with a window expert or use an online calculator to get a more accurate estimate of your potential energy savings.


Are Replacement Windows Worth It?

Whether or not it is worth the investment to replace your energy-efficient windows depends on a variety of factors. Here are some things to consider:

  1. Age and condition of your current windows: If your current windows are old and in poor condition, they may be causing drafts and energy loss, even if they are supposed to be energy-efficient. In this case, replacing them with new energy-efficient windows could make a significant difference in your energy bills and overall comfort.

  2. Energy savings: Energy-efficient windows can help reduce your energy bills by improving your home's insulation and reducing air leaks. Over time, the energy savings can help offset the cost of the new windows.

  3. Return on investment: While energy-efficient windows can be more expensive than standard windows, they can also provide a good return on investment over time. According to the U.S. Department of Energy, homeowners can save up to $465 per year by replacing single-pane windows with energy-efficient windows.

  4. Comfort: Energy-efficient windows can also improve the comfort of your home by reducing drafts and keeping your home warmer in the winter and cooler in the summer.

In summary, if your current windows are old and in poor condition or you are experiencing high energy bills due to air leaks and poor insulation, it may be worth the investment to replace them with energy-efficient windows. However, if your current windows are in good condition and you are not experiencing high energy bills, it may not be necessary to replace them at this time.


Even though there is no set scientific formula, it is easy to see that some people will save more than others when installing replacement windows, but everyone will certainly benefit from them.  If you choose a high quality window and have a well-qualified, professional, experienced installer install the windows, you can expect a minimum of 25% and a maximum of 52% savings on your energy bill.  For example, you may spend $10,000 on replacement windows but end up saving around 40% of your annual $3000 energy bill, amounting to a savings of $1200 a year. Not only will your savings end up paying for the cost of the windows, but more importantly, you will experience a more comfortable home with enhanced beauty and value. You will also have a greater appreciation for your home and will want to show off your new windows, and probably brag to your friends and neighbors about your magically reduced utility bills.

If you have any further questions about pricing on high quality patio doors, please contact us directly, because we’d love to give you any information that could be helpful to you in your decision-making process.