How Much Will New Windows Lower Your Utah Energy Bills?

How Windows Affect Your Energy Bills

Windows are the thinnest, least-insulated surfaces in your home's building envelope. A typical exterior wall provides R-13 to R-19 of insulation. Your attic should be R-38 to R-60. But even a good modern window only delivers R-3 to R-6. That makes windows the primary weak point for heat transfer in every Utah home.

The Department of Energy estimates that windows account for 25 to 30 percent of residential heating and cooling energy use nationwide. In Utah, where winter heating loads are substantial and summer cooling loads are significant, windows can be responsible for an even larger share of your energy costs.

Heat escapes through windows in three ways: conduction through the glass and frame, convection (air leakage through gaps and failed seals), and radiation (infrared heat passing through the glass). Old windows with single-pane glass, aluminum frames, and worn weatherstripping allow all three mechanisms to operate at full throttle. Modern energy-efficient windows with Low-E coatings, gas fills, and thermally broken frames attack all three pathways simultaneously.

The result is measurable, significant savings on your monthly utility bills. How much depends on what you are replacing, which is the focus of this guide.

Utah Energy Rates and Baseline Costs

Understanding your savings potential starts with knowing what Utah homeowners pay for energy.

Natural Gas (Heating)

Dominion Energy serves most of Utah for natural gas. As of early 2026, residential rates average approximately $1.00 to $1.10 per therm. A typical 2,000-square-foot Utah home uses 600 to 900 therms per year for heating, costing $600 to $990 annually. Heating season runs roughly from October through April, with December through February being the peak months.

Electricity (Cooling and Some Heating)

Rocky Mountain Power provides electricity to most of the Wasatch Front. Residential rates average approximately $0.105 to $0.115 per kWh. A typical Utah home uses 800 to 1,200 kWh per month in summer for cooling. Annual electricity for cooling costs approximately $400 to $600 for homes with central air conditioning.

Total Window-Related Energy Cost

If windows are responsible for 25 to 30 percent of heating and cooling energy, a typical Utah household spends $250 to $475 per year on energy that is lost through or influenced by window performance. For homes with poor windows, this number can be significantly higher.

Savings by Current Window Condition

Your savings depend almost entirely on the condition and technology of your existing windows. Here is what to expect for different starting points, based on replacing all windows with modern Low-E, argon-filled units (U-factor 0.22 or lower).

Replacing Single-Pane Windows

Single-pane windows with aluminum frames, common in Utah homes built before 1980, have U-factors of 1.00 to 1.10. Replacing them with modern double-pane or triple-pane Low-E windows delivers the largest savings:

• Heating savings: 35 to 40 percent reduction in window-related heating loss
• Cooling savings: 20 to 30 percent reduction in solar heat gain
• Annual dollar savings: $600 to $1,200 depending on home size and energy rates
• You will feel the difference within hours of installation

Replacing 1990s-Era Double-Pane (No Low-E)

Many Utah homes built in the 1980s and 1990s have double-pane windows without Low-E coatings, often with aluminum or early vinyl frames. These units have U-factors around 0.45 to 0.55. Upgrading to modern Low-E units delivers:

• Heating savings: 20 to 30 percent reduction in window-related heating loss
• Cooling savings: 15 to 20 percent reduction in solar heat gain
• Annual dollar savings: $350 to $700
• Condensation problems will likely disappear entirely

Replacing Early 2000s Double-Pane Low-E

Homes built from 2000 to 2010 often have first-generation Low-E double-pane windows with U-factors around 0.30 to 0.35. These are still reasonably functional, and the upgrade to current technology delivers more modest savings:

• Heating savings: 10 to 18 percent reduction in window-related heating loss
• Cooling savings: 8 to 12 percent reduction in solar heat gain
• Annual dollar savings: $200 to $400
• The comfort and noise reduction improvements may be more noticeable than the bill savings

Replacing Seal-Failed Windows

If you have double-pane windows where the seal has failed (visible fogging between the panes), those units have lost their insulating gas and are performing far below their original rating. A seal-failed double-pane window with depleted gas fill performs only slightly better than a single-pane unit. Replacing seal-failed windows delivers savings in the upper range of the categories above.

Heating Savings Breakdown

Let's walk through a specific example to show how the math works.

Home: 2,200-square-foot two-story in South Jordan, built 1995 Current windows: 18 double-pane, non-Low-E, vinyl frame (U-factor 0.48) Total window area: 216 square feet Annual heating therms: 780 Annual heating cost: $820

Window-related heating loss is approximately 28 percent of total heating energy: 218 therms, or $229 per year.

New windows: Triple-pane Low-E, argon fill (U-factor 0.18)

The U-factor drops from 0.48 to 0.18, a 62 percent reduction in heat transfer through the windows. But windows are only 28 percent of the heating load, so the whole-house heating savings are: 62% x 28% = 17.4% reduction in total heating cost.

Annual heating savings: $820 x 17.4% = $143 per year on natural gas.

This matches the 15 to 20 percent range commonly cited for this type of upgrade.

Cooling Savings Breakdown

The cooling calculation works differently because solar heat gain through windows (SHGC) matters as much as conduction (U-factor).

Using the same South Jordan home:

Annual cooling electricity: 3,600 kWh (June through September) Annual cooling cost: $396

Window-related cooling load comes from two sources: solar heat gain and conductive heat transfer from hot outdoor air. Windows typically account for 30 to 40 percent of the cooling load in Utah, where afternoon sun hits west-facing windows relentlessly from May through September.

New Low-E windows with SHGC of 0.25 (versus no Low-E coating at approximately 0.65) reduce solar heat gain by approximately 60 percent. Combined with the U-factor improvement for conductive gain, total cooling savings are typically 20 to 25 percent.

Annual cooling savings: $396 x 22% = $87 per year on electricity.

Combined annual savings for this home: $230 per year, or approximately $19 per month averaged across the year.

Calculate Your Estimated Savings

Use the calculator below to estimate savings based on your specific situation. Adjust the inputs to match your home's window count, current energy bills, and the expected efficiency improvement.

For help choosing the right savings percentage, use these guidelines:

• Replacing single-pane: use 35 to 40 percent heating, 25 to 30 percent cooling
• Replacing 1990s double-pane (no Low-E): use 20 to 30 percent heating, 15 to 20 percent cooling
• Replacing 2000s Low-E double-pane: use 10 to 18 percent heating, 8 to 12 percent cooling

Factors That Affect Real-World Savings

The numbers above are based on typical conditions, but several factors push your actual savings higher or lower.

Factors That Increase Savings

Large window-to-wall ratio. Homes with lots of glass (common in modern Utah construction) have more surface area affected by window upgrades. A great room with 80 square feet of windows benefits more from better glass than a bedroom with 20 square feet.

West-facing windows. If your home has significant west exposure, the cooling savings from Low-E coatings will be substantial. West-facing windows receive the most intense solar heat load in Utah summers.

Air leakage from current windows. If you can feel drafts around your existing windows, much of your heat loss is through air infiltration rather than conduction. New windows with factory-sealed sashes and proper installation will eliminate this pathway entirely, often delivering savings at the high end of estimates.

Extreme elevation. Homes in Park City, Heber, and the mountain communities experience colder winters than the valley floor, amplifying heating savings.

Factors That Reduce Savings

Well-insulated home. If your walls and attic are already well-insulated, windows represent a smaller fraction of total heat loss. The percentage savings from windows remains the same, but the dollar savings are smaller because your total energy use is already lower.

Small home. A 1,200-square-foot rambler with 12 small windows has less total window area than a 3,000-square-foot two-story with 24 windows. Absolute dollar savings scale with window area.

Moderate thermostat settings. Homeowners who keep their thermostat at 66 degrees in winter have lower heating bills to begin with, so the dollar savings from better windows are proportionally smaller.

Shaded windows. Windows shaded by trees, overhangs, or neighboring structures have lower solar heat gain regardless of the glass type. Upgrading shaded windows still improves insulation but yields less cooling benefit.

Maximizing Savings Beyond Windows

Window replacement delivers the best return when it is part of a broader envelope improvement strategy. Consider these complementary upgrades that multiply the effectiveness of your new windows:

Attic insulation. If your attic has less than R-38, adding insulation is one of the most cost-effective energy upgrades available. Utah has excellent contractors who can blow in cellulose or fiberglass insulation in a single day.

Air sealing. Sealing gaps around penetrations, rim joists, and attic hatches prevents conditioned air from escaping through pathways that even new windows cannot address.

Weatherstripping on doors. While your windows are being replaced, check the weatherstripping on your exterior doors. Doors account for 10 to 15 percent of air leakage and are inexpensive to seal.

Programmable or smart thermostat. Reducing heating and cooling when you are asleep or away complements window efficiency by reducing total energy demand.

The Payback Timeline

The energy payback for window replacement in Utah depends on the total project cost and annual savings.

For a $10,000 project saving $500 per year: 20-year simple payback. Add $1,100 in tax credits and rebates and the effective payback drops to approximately 18 years.

For a $12,000 project saving $800 per year: 15-year simple payback. With incentives: approximately 13 years.

For a $15,000 project saving $1,100 per year (replacing single-pane in a larger home): approximately 14-year simple payback. With incentives: approximately 12 years.

These timelines do not account for rising energy costs. If natural gas and electricity rates increase at their historical average of 2 to 3 percent per year, the actual payback shortens by 2 to 3 years because your savings grow each year while your window cost is fixed.

The payback also does not account for increased home value. Our analysis of window replacement ROI shows that energy-efficient windows recoup 65 to 75 percent of their cost at resale, which effectively subsidizes the payback further.

For details on available financial incentives that reduce your upfront cost and accelerate payback, see our guide on Utah energy rebates and tax credits for windows. And for a comprehensive understanding of window energy technology, including U-factors, Low-E coatings, and gas fills, start with our complete energy-efficient windows guide.