ENERGY STAR Climate Zones

ENERGY STAR CLIMATE ZONES

Understand the Zones for Better Energy Efficiency

ENERGY STAR Climate Zones Map

Zones and Key Factors

Different regions of the United States are divided into climate zones to ensure that windows and doors meet appropriate energy efficiency requirements. Below are updated U-Factor and SHGC (Solar Heat Gain Coefficient) values for each zone, including prescriptive and equivalent energy performance criteria.

Climate Zone U-Factor SHGC Approach
Northern ≤ 0.27 Any Prescriptive
Northern 0.28 ≥ 0.32 Equivalent Energy Performance
Northern 0.29 ≥ 0.37 Equivalent Energy Performance
Northern 0.30 ≥ 0.42 Equivalent Energy Performance
North-Central ≤ 0.30 ≤ 0.40 -
South-Central ≤ 0.30 ≤ 0.25 -
Southern ≤ 0.40 ≤ 0.25 -
Air Leakage Rating ≤ 0.3 cfm/ft2 - -

A window’s U-factor measures how effectively it insulates against heat transfer, both from the inside out during colder months and from the outside in during warmer months. A lower U-factor indicates stronger insulation performance, meaning the window is better at keeping indoor temperatures stable and reducing the workload on your heating and cooling systems. In turn, this can lead to noticeable savings on energy bills, a more comfortable indoor environment, and a reduced carbon footprint over time.