Best U-Factor and SHGC for Windows in Washington

Data updated October 12, 2026.

ENERGY STAR Version 7.0 places all of Washington in its Northern climate zone. ENERGY STAR windows there need a U-factor of 0.22 or lower and an SHGC of 0.17 or higher.

Across Washington, in the GlassBase heating and cooling model, replacing a single-pane window with an ENERGY STAR window saves 433 kWh per window per year. Upgrading a double-pane window saves 121 kWh.

In the Northern zone, the SHGC limit is a minimum, not a maximum. ENERGY STAR also lets a window with a slightly higher U-factor qualify if its SHGC is high enough to collect more winter sun. See window energy ratings in the US for the full table.

What matters most for windows in Washington

In Washington, most of the modeled saving comes from heating: 345 kWh of heating load against 89 kWh of cooling load per window per year, for a single-pane to ENERGY STAR upgrade. U-factor measures how fast heat passes through the window. A lower U-factor means less heat lost in winter.

Results vary inside the state; see the city table below.

Modeled savings per window per year across Washington

One window of 39 × 59 in (1 × 1.5 m), averaged over eight facing directions. Weather: 34 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	295	17	312	11.9	13	20
Single-pane → ENERGY STAR (Northern)	345	89	433	13.8	19	27
Double-pane → ENERGY STAR (Northern)	49	72	121	2.0	6	7

Dollar figures use Washington average prices, not your utility's rate. Electricity $0.1311/kWh: Washington 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 $1.61/therm: Washington 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 Northern 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 Washington

Modeled savings per window per year in Washington cities with a GlassBase page.

City	ENERGY STAR zone	Total, kWh/yr single-pane → ENERGY STAR	Total, kWh/yr double-pane → ENERGY STAR
Seattle	Northern	335	74
Spokane	Northern	614	211
Vancouver	Northern	411	139
Tacoma	Northern	433	107
Olympia	Northern	444	116
Everett	Northern	347	60
Kent	Northern	362	94
Puyallup	Northern	456	116
Renton	Northern	363	98
Bellevue	Northern	363	98
Yakima	Northern	635	241
Bellingham	Northern	386	65
Lynnwood	Northern	347	60
Kennewick	Northern	640	283
Redmond	Northern	363	98
Federal Way	Northern	358	83
Kirkland	Northern	339	66
Snohomish	Northern	347	60
Wenatchee	Northern	606	234
Otis Orchards	Northern	619	217
La Push	Northern	372	59

Payback of each upgrade in Washington

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 Washington is in the Northern zone. The ENERGY STAR climate zone finder gives the zone for an address.

How much can new windows save in Washington?

Across Washington, for a single-pane to ENERGY STAR upgrade, the GlassBase heating and cooling model saves 433 kWh per window per year. At Washington's 2025 average prices from the U.S. Energy Information Administration (EIA), the single-pane to ENERGY STAR upgrade is worth about $19 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.