Best U-Factor and SHGC for Windows in Hawaii
Data updated October 12, 2026.
ENERGY STAR Version 7.0 places all of Hawaii in its Southern climate zone. ENERGY STAR windows there need a U-factor of 0.32 or lower and an SHGC of 0.23 or lower.
Across Hawaii, in the GlassBase heating and cooling model, replacing a single-pane window with an ENERGY STAR window saves 724 kWh per window per year. Upgrading a double-pane window saves 564 kWh.
What matters most for windows in Hawaii
In Hawaii, most of the modeled saving comes from cooling: 720 kWh of cooling load against 3 kWh of heating load per window per year, for a single-pane to ENERGY STAR upgrade. SHGC measures how much solar heat the window lets in. A lower SHGC means less heat for the air conditioner to remove.
Results vary inside the state; see the city table below.
Modeled savings per window per year across Hawaii
One window of 39 × 59 in (1 × 1.5 m), averaged over eight facing directions. Weather: 10 TMY3 weather stations.
| Upgrade | Heating saved, kWh/yr | Cooling saved, kWh/yr | Total, kWh/yr | Natural gas saved, therms/yr gas furnace |
Heat pump + AC, $/yr | Gas furnace + AC, $/yr |
|---|---|---|---|---|---|---|
| Single-pane → double-pane | 3 | 156 | 159 | 0.1 | 26 | 26 |
| Single-pane → ENERGY STAR (Southern) | 3 | 720 | 724 | 0.1 | 117 | 118 |
| Double-pane → ENERGY STAR (Southern) | 0 | 564 | 564 | 0.0 | 92 | 92 |
Dollar figures use Hawaii average prices, not your utility's rate. Electricity $0.4059/kWh: Hawaii residential average, 2025. Source: U.S. EIA, Electric Power Monthly, Table 5.6.B, residential sector, year-to-date through December 2025, retrieved 2026-10-06. Natural gas $5.71/therm: Hawaii residential average, 2025. Source: U.S. EIA, Natural Gas Prices: price delivered to residential consumers, and heat content of natural gas delivered to consumers, 2025, retrieved 2026-10-06. Heat pump COP 3.2, air conditioner COP 2.5, gas furnace efficiency 85%.
The single-pane and double-pane windows use values from the calculator's reference-window table; the ENERGY STAR window is at the Southern zone limits. kWh here measures heat, not electricity on a bill. Air leakage and the rest of the house are not modeled. Model version tmy3-hourly-iso13790/f4822a26309b, data run October 12, 2026. How the model works.
Cities in Hawaii
Modeled savings per window per year in Hawaii cities with a GlassBase page.
| City | ENERGY STAR zone | Total, kWh/yr single-pane → ENERGY STAR | Total, kWh/yr double-pane → ENERGY STAR |
|---|---|---|---|
| Honolulu | Southern | 755 | 587 |
Payback of each upgrade in Hawaii
Calculate savings for your ZIP code
Compare states: window energy savings by state.
Frequently asked questions
Which ENERGY STAR climate zone is my home in?
All of Hawaii is in the Southern zone. The ENERGY STAR climate zone finder gives the zone for an address.
How much can new windows save in Hawaii?
Across Hawaii, for a single-pane to ENERGY STAR upgrade, the GlassBase heating and cooling model saves 724 kWh per window per year. At Hawaii's 2025 average prices 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. Results differ from place to place; use the calculator for your ZIP code.
Is the ENERGY STAR zone the same as the building code climate zone?
No. ENERGY STAR uses four zones of its own, assigned by state and county. Building energy codes use the IECC climate zones, a separate map with its own window requirements. A window can meet one and not the other, so check both if your project needs a permit.