Best U-Factor and SHGC for Windows in South Carolina
Data updated October 12, 2026.
ENERGY STAR Version 7.0 splits South Carolina into 2 climate zones: South-Central, Southern. The limits for each are in the table below. Check your address with the ENERGY STAR climate zone finder.
| ENERGY STAR zone | U-factor | SHGC |
|---|---|---|
| South-Central | 0.28 or lower | 0.23 or lower |
| Southern | 0.32 or lower | 0.23 or lower |
Across South Carolina, in the GlassBase heating and cooling model, replacing a single-pane window with an ENERGY STAR window saves 521 kWh per window per year. Upgrading a double-pane window saves 283 kWh.
What matters most for windows in South Carolina
In South Carolina, most of the modeled saving comes from cooling: 351 kWh of cooling load against 170 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 South Carolina
One window of 39 × 59 in (1 × 1.5 m), averaged over eight facing directions. Weather: 14 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 | 158 | 81 | 239 | 6.3 | 12 | 15 |
| Single-pane → ENERGY STAR (each location's zone) | 170 | 351 | 521 | 6.8 | 29 | 32 |
| Double-pane → ENERGY STAR (each location's zone) | 13 | 270 | 283 | 0.5 | 17 | 17 |
Dollar figures use South Carolina average prices, not your utility's rate. Electricity $0.1496/kWh: South Carolina 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 $1.64/therm: South Carolina residential average, 2024. Source: U.S. EIA, Natural Gas Prices: price delivered to residential consumers, and heat content of natural gas delivered to consumers, 2024, 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. In South Carolina, each location uses the limits of its own ENERGY STAR zone (South-Central, Southern). 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 South Carolina
Modeled savings per window per year in South Carolina cities with a GlassBase page.
| City | ENERGY STAR zone | Total, kWh/yr single-pane → ENERGY STAR | Total, kWh/yr double-pane → ENERGY STAR |
|---|---|---|---|
| Greenville | South-Central | 477 | 215 |
| Charleston | South-Central | 543 | 329 |
| Myrtle Beach | South-Central | 477 | 268 |
| Summerville | South-Central | 543 | 329 |
| Spartanburg | South-Central | 502 | 252 |
| Rock Hill | South-Central | 507 | 262 |
| Mount Pleasant | South-Central | 543 | 329 |
| North Charleston | South-Central | 543 | 329 |
Payback of each upgrade in South Carolina
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?
South Carolina has 2 zones: South-Central, Southern. ENERGY STAR assigns them by county, and in some places by ZIP code. The ENERGY STAR climate zone finder gives the zone for an address.
How much can new windows save in South Carolina?
Across South Carolina, for a single-pane to ENERGY STAR upgrade, the GlassBase heating and cooling model saves 521 kWh per window per year. At South Carolina's 2025 average prices from the U.S. Energy Information Administration (EIA), the single-pane to ENERGY STAR upgrade is worth about $29 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.