NOCO Blog

Return on Investment: Windows vs. Attic Insulation

After researching various ways to improve my 1960 built home's energy efficiency in Loveland, CO, I decided to start by replacing the original windows with modern high performance, low E, windows; in addition I had specially coated windows installed the south side of the house. It was a significant investment ($38,000 for 27 windows) and I anticipated a noticeable decrease in my energy bills and increase in comfort. However, after the rest of the summer and into the winter season, I was surprised to find that the difference in temperatures my air conditioner could achieve and that my heating costs was near zero.  One very sunny room became comfortable but that was the only perceived increase.

Motivated by the modest results from the window replacement, I then turned my attention to upgrading the insulation in my attic.  It had very little cellulose, maybe R-15) in it and it was a mess, with bird nests, rodent droppings, etc, so I removed it.  To my surprise, I could see light coming in through every can light and could feel hot air coming up through the many holes from electrical wires.  I replaced the 15 can lights with IC rated (insulation contact rated) LED fixtures, sealed them up, sealed every hole where an electrical wire came up through.  I then added 19-3/4” of fiberglass/wool insulation.

The cost of this upgrade was considerably less than the windows ($4000 vs $38,000), and the installation was quick and non-intrusive. To my astonishment, the comfort level and impact on my energy bills was immediately evident. We could only run the fireplace for 10 minutes before the living room reached 80 degrees; it would barely keep 74 running constantly before!  The first winter bill my heating costs dropped by 75% (in therms, not just cost) and the house felt warmer and more comfortable. The summers brought a similar revelation, with the home staying cooler and less reliant on air conditioning, our air conditioner could now get our house to 70 degrees on the hottest of summer days. This experience underscored the importance of prioritizing insulation to maximize energy efficiency and comfort, providing a stark contrast to the more modest benefits of window replacement in my Colorado home.

When considering home improvements, especially in areas with variable climates like Colorado, homeowners often look at insulation upgrades and window replacements as ways to increase comfort and decrease energy costs. Both of these improvements can lead to significant savings over time, but they come with upfront costs and varying degrees of return on investment (ROI). Here, we will delve into the ROI of upgrading insulation from R-19 to R-49 (or R-60) compared to installing new windows.

The windows may never pay for themselves; the attic and air sealing have nearly paid off in just three years.