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    Window Energy Savings by State, 2026

    Data updated October 12, 2026. Model version tmy3-hourly-iso13790/f4822a26309b.

    Replacing a single-pane window with one that meets the ENERGY STAR Version 7.0 limits for its climate zone saves the most energy in North Dakota: 793 kWh of heating and cooling load per window per year. The saving is smallest in California, at 369 kWh. The median across 50 states and the District of Columbia is 568 kWh. These are GlassBase model results for one window of 39 × 59 in (1 × 1.5 m), averaged over eight facing directions, with NREL TMY3 typical-year weather.

    Key findings

    • The largest heating saving from a single-pane to ENERGY STAR upgrade is in Alaska: 706 kWh per window per year.
    • The largest cooling saving from the same upgrade is in Hawaii: 720 kWh per window per year.
    • For a home that already has double-pane windows, an upgrade to ENERGY STAR saves the most in Hawaii: 564 kWh per window per year.
    • At Hawaii's 2025 electricity price of 40.6¢/kWh, from the U.S. Energy Information Administration (EIA), the single-pane to ENERGY STAR upgrade is worth about $117 per window per year with a heat pump.

    The figures measure heat (thermal load), not the electricity or gas on a bill. How much fuel that heat represents depends on the heating and cooling equipment. Your own savings depend on your window size, facing, shading and house.

    Estimate savings for your ZIP code with the GlassBase calculator

    Energy saved per window per year, by state

    Heating and cooling load saved by one window of 39 × 59 in (1 × 1.5 m), averaged over eight facing directions. Sorted by the single-pane to ENERGY STAR total, highest first.

    State ENERGY STAR zone(s) Heating saved, kWh/yr
    single-pane → ENERGY STAR    		 Cooling saved, kWh/yr
    single-pane → ENERGY STAR    		 Total, kWh/yr
    single-pane → ENERGY STAR    		 Total, kWh/yr
    single-pane → double-pane    		 Total, kWh/yr
    double-pane → ENERGY STAR    		 Weather stations
    North Dakota Northern 634 159 793 551 242 18
    Arizona Southern, Northern, South-Central, North-Central 99 654 753 301 454 25
    South Dakota Northern 533 206 739 484 255 22
    Minnesota Northern 577 150 727 504 223 63
    Hawaii Southern 3 720 724 159 564 10
    Alaska Northern 706 4 710 582 128 73
    Nevada South-Central, Northern, North-Central 194 512 706 323 383 19
    Nebraska Northern 431 269 699 416 283 30
    Iowa Northern 463 226 689 429 260 51
    Montana Northern 520 155 675 467 207 24
    Wyoming Northern 495 167 662 451 211 20
    Utah Northern, South-Central 354 302 656 369 286 18
    Wisconsin Northern 511 137 648 452 197 35
    Idaho Northern 423 221 644 404 240 17
    Michigan Northern 460 165 625 415 210 34
    Illinois Northern, North-Central 408 215 623 386 237 35
    Colorado Northern, North-Central 408 210 619 390 229 33
    Oklahoma South-Central, North-Central 238 377 615 313 302 28
    Vermont Northern 513 102 615 446 168 9
    Maine Northern 518 93 612 451 160 18
    New Hampshire Northern 474 133 606 422 184 12
    Indiana Northern, North-Central 396 207 603 374 229 19
    Florida Southern 45 553 598 178 421 45
    Texas Southern, South-Central, North-Central 117 479 596 239 358 71
    Kansas North-Central, Northern 333 240 573 343 229 36
    Arkansas South-Central, North-Central 228 339 568 288 279 23
    New Mexico Northern, North-Central, South-Central 267 297 564 303 261 25
    Ohio Northern, North-Central 399 164 562 366 196 24
    Mississippi South-Central, Southern 158 402 561 243 318 19
    Missouri North-Central, Northern, South-Central 323 229 552 330 222 37
    Louisiana Southern, South-Central 107 436 543 212 333 22
    Rhode Island Northern 397 145 542 363 179 5
    Massachusetts Northern 410 128 538 370 168 22
    Pennsylvania Northern, North-Central 374 154 528 346 181 32
    Alabama South-Central, Southern 165 359 524 236 288 25
    Tennessee North-Central, South-Central 242 282 524 280 244 18
    South Carolina South-Central, Southern 170 351 521 239 283 14
    New York Northern, North-Central 371 148 519 342 177 34
    Georgia South-Central, Southern 181 335 517 246 271 27
    Kentucky North-Central 321 194 515 314 201 19
    Connecticut Northern 382 132 514 348 166 14
    West Virginia North-Central, Northern 356 153 508 328 181 22
    Delaware North-Central 331 175 506 317 189 4
    Maryland North-Central, Northern 313 192 505 310 195 19
    Virginia North-Central, South-Central, Northern 286 219 505 296 208 39
    North Carolina South-Central, North-Central 212 292 504 258 246 35
    New Jersey North-Central, Northern 336 165 501 320 182 17
    District of Columbia North-Central 287 211 497 299 198 1
    Oregon Northern 321 136 457 302 155 29
    Washington Northern 345 89 433 312 121 34
    California South-Central, North-Central, Northern, Southern 138 230 369 184 185 80

    Download the data (CSV) · License: CC BY 4.0

    Estimated dollar savings per window per year

    Single-pane to ENERGY STAR upgrade, priced at each state's average energy prices. These are state averages, not your utility's rate.

    State Electricity, ¢/kWh (2025) Natural gas, $/therm (2025) Heat pump + AC, $/yr Gas furnace + AC, $/yr
    North Dakota 11.8 0.91 31 31
    Arizona 15.3 1.81 45 47
    South Dakota 13.4 0.92 33 31
    Minnesota 15.8 1.04 38 34
    Hawaii 40.6 5.71 117 118
    Alaska 26.1 1.31 58 38
    Nevada 13.2 1.26 35 37
    Nebraska 12.3 1.08 30 32
    Iowa 13.7 1.00 32 31
    Montana 13.0 0.85 29 26
    Wyoming 13.4 1.11 30 31
    Utah 13.1 0.97 30 30
    Wisconsin 18.2 1.02 39 31
    Idaho 11.8 0.74 26 23
    Michigan 20.0 1.03 42 32
    Illinois 17.7 1.07 38 33
    Colorado 15.9 1.05 34 31
    Oklahoma 13.1 1.39 30 33
    Vermont 22.9 1.72 46 45
    Maine 27.8 1.82† 55 48
    New Hampshire 24.6 1.79 49 47
    Indiana 16.2 1.09 34 31
    Florida 15.2 2.49 36 38
    Texas 15.5 1.91 35 39
    Kansas 14.6 1.43 29 33
    Arkansas 12.8 1.88 27 35
    New Mexico 15.1 0.96 31 28
    Ohio 17.0 1.30 32 32
    Mississippi 14.0 1.63 30 33
    Missouri 13.5 1.46 26 31
    Louisiana 12.6 1.70 26 29
    Rhode Island 29.5 2.11† 54 51
    Massachusetts 30.5 2.43 55 56
    Pennsylvania 19.3 1.45 34 34
    Alabama 16.1 1.70 31 34
    Tennessee 13.2 1.16 25 26
    South Carolina 15.0 1.64† 29 32
    New York 26.4 1.70 46 41
    Georgia 14.7 1.98 28 34
    Kentucky 13.2 1.36 24 28
    Connecticut 29.4 1.63† 51 41
    West Virginia 15.4 1.27 27 28
    Delaware 17.1 1.54 30 33
    Maryland 19.5 1.55† 34 34
    Virginia 15.3 1.60 27 32
    North Carolina 14.0 1.58† 26 30
    New Jersey 22.6 1.37 39 33
    District of Columbia 21.9 1.61 38 37
    Oregon 15.4 1.55 24 28
    Washington 13.1 1.61 19 27
    California 32.5 2.15 44 42

    Energy prices from the U.S. Energy Information Administration (EIA). Electricity: U.S. EIA, Electric Power Monthly, Table 5.6.B, residential sector, year-to-date through December 2025, 2025. Natural gas: U.S. EIA, Natural Gas Prices: price delivered to residential consumers, and heat content of natural gas delivered to consumers, 2025, 2025. Retrieved October 6, 2026. † Price for an earlier year: EIA has not published a 2025 figure for this state.

    Heat pump + AC = heating kWh ÷ 3.2 × electricity price + cooling kWh ÷ 2.5 × electricity price. Gas furnace + AC = therms saved × gas price + cooling kWh ÷ 2.5 × electricity price; therms assume a furnace efficiency of 85%.

    How these numbers were calculated

    • Model: the same calculation as the GlassBase window energy calculator: heat loss through the window (U-factor × area × heating degree-hours), solar gain through the glass (SHGC × solar radiation on the wall), and the useful share of winter sun under ISO 13790. Window U-factor follows ISO 10077-1.
    • Weather: NREL TMY3 typical-year data. Each ZIP code uses its nearest weather station, as the calculator does. A state figure is the population-weighted average over the state's ZIP codes; the station column counts the stations behind it.
    • Windows compared: the single-pane and double-pane windows use the values in the calculator's reference-window table. The ENERGY STAR window is at the Version 7.0 limits of each ZIP code's zone: the highest U-factor allowed and the SHGC limit (in the Northern zone, the lowest SHGC allowed). In states that span more than one ENERGY STAR zone, each location uses its own zone's limits.
    • Facing: results are the mean of eight facing directions (N, NE, E, SE, S, SW, W, NW).
    • Not included: air leakage, the rest of the house (insulation, internal gains, thermostat schedules) and installation quality. The values are model estimates, not NFRC ratings or ENERGY STAR certification.

    Read the full calculator methodology and how ENERGY STAR zones and limits work.

    Frequently asked questions

    Which state saves the most energy with new windows?

    In this data run, North Dakota shows the largest saving for replacing a single-pane window with an ENERGY STAR window: 793 kWh of heating and cooling load per window per year. The ranking can change between upgrades and between kWh and dollars, because energy prices differ by state. Use the table to compare all 50 states and the District of Columbia.

    Will my windows save this much?

    Not necessarily. The table shows one window of 39 × 59 in (1 × 1.5 m), averaged over eight facing directions, in a typical weather year. Your result depends on window size and count, which way each window faces, shading, the windows you have now and the windows you buy. The calculator takes these inputs for your ZIP code.

    Why are the numbers in kWh rather than dollars?

    kWh describes the heat the window saves, which does not depend on fuel prices. Dollar savings depend on your heating system and your local prices. The dollar table converts kWh with each state's 2025 average prices from the U.S. Energy Information Administration (EIA).

    Can I use this data in an article or report?

    Yes. The data is published under the CC BY 4.0 license (https://creativecommons.org/licenses/by/4.0/): you may share and adapt it, also commercially, if you credit "GlassBase, Window energy savings by state" and link to this page. Please cite it as shown in "How to cite this data" and include the data run date, October 12, 2026.

    First published October 12, 2026.