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Energy Code Reference
Energy code requirements by climate zone including R-values, U-factors, and design temperatures for building envelope compliance.
Click a state to jump to its climate zone details
Very hot to hot climates. Focus on cooling efficiency and solar heat gain control.
Mixed climates with both heating and cooling needs. Balance between insulation and ventilation.
Cold to subarctic climates. High insulation requirements, ice barrier and vapor control critical.
Very hot climate. Minimal heating requirements, significant cooling load. Typical locations: South Florida, Hawaii, Puerto Rico, US Virgin Islands.
Very hot and humid climate. Minimal heating requirements, significant cooling and dehumidification load. Typical locations: South Florida (Miami, Keys), Hawaii, Puerto Rico, US Virgin Islands, Guam.
Hot-humid climate with high moisture levels. Significant cooling load, moderate heating. Typical locations: Houston, New Orleans, Jacksonville, Tampa, Miami-Dade inland.
Hot-dry climate with low humidity. High cooling load, moderate heating. Large diurnal temperature swings. Typical locations: Phoenix, Tucson, Las Vegas.
Warm-humid climate with moderate heating and cooling loads. Typical locations: Atlanta, Charlotte, Raleigh, Memphis, Dallas.
Warm-dry climate. Moderate heating, significant cooling. Low humidity. Typical locations: Los Angeles (inland), Albuquerque, El Paso.
Warm-marine climate with moderate temperatures year-round. Coastal influence moderates extremes. Typical locations: San Francisco, San Diego coastal, Santa Barbara.
Climate Zone 4A covers the mid-Atlantic and parts of the Southeast. Characterized by moderate heating and cooling loads with significant humidity. Requires balanced insulation strategies, ice dam protection, and moisture control. Virginia counties in Zone 4 include most of the Shenandoah Valley, Piedmont, and Northern Virginia.
Mixed-dry climate. Cold winters, hot summers, low humidity. High elevation desert areas. Typical locations: Albuquerque highlands, Flagstaff.
Mixed-marine climate. Mild winters, cool summers, high humidity. Significant moisture management concerns. Typical locations: Seattle, Portland, Vancouver WA.
Cool-humid climate with cold winters and mild summers. Dominant heating load. Ice dam prevention critical. Typical locations: Chicago, Boston, New York City, Pittsburgh, Cleveland, Detroit.
Cool-dry climate with cold winters and warm, dry summers. High altitude. Large temperature swings. Typical locations: Denver, Salt Lake City, Boise.
Cool-marine climate. Very limited geographic area in US. Cool year-round with high moisture. Typical locations: Small areas of coastal Washington/Oregon.
Cold-humid climate with severe winters. Heating dominant. Ice dams common. Enhanced insulation critical. Typical locations: Minneapolis, Milwaukee, Buffalo, Burlington VT, western Virginia mountains.
Cold-dry climate with severe winters. High altitude mountain regions. Low humidity reduces moisture concerns. Typical locations: Montana, Idaho mountains, Wyoming.
Very cold climate with extended severe winters. Heating strongly dominant. Maximum insulation requirements. Typical locations: International Falls MN, Duluth, Upper Peninsula MI, inland Alaska.
Subarctic climate with extreme cold. Very short building season. Permafrost considerations. Maximum thermal protection required. Typical locations: Fairbanks, Northern Alaska.
Arctic climate unique to Alaska North Slope. Extreme cold (-60F design temps), continuous permafrost, minimal daylight in winter. Maximum thermal protection required. Permafrost foundation design mandatory. Typical locations: Utqiagvik (Barrow), Prudhoe Bay, Deadhorse, Point Hope, Wainwright.
Cool humid coastal climate. Foggy, mild temperatures year-round. Minimal cooling load, moderate heating. Typical locations: Arcata, Eureka, Crescent City (North Coast).
Cool marine valleys with wider temperature swings than coast. Moderate heating, some cooling. Typical locations: Santa Rosa, Napa, Ukiah (North Bay wine country).
Mild marine climate moderated by San Francisco Bay and Pacific fog. Minimal cooling, moderate heating. Typical locations: San Francisco, Oakland, Berkeley, Daly City.
Mild dry climate with warmer summers than coast. Moderate heating and cooling. Typical locations: San Jose, Sunnyvale, Santa Clara, Fremont (Silicon Valley).
Cool coastal climate with marine influence. Mild year-round temperatures. Typical locations: Santa Maria, San Luis Obispo, Santa Barbara coastal areas.
Mild marine climate moderated by Pacific Ocean. Low heating and cooling loads. Typical locations: Long Beach, LAX area, Santa Monica, Torrance, Hermosa Beach.
Mild dry coastal climate. Year-round moderate temperatures. Lowest heating/cooling requirements. Typical locations: San Diego, Oceanside, Carlsbad, Encinitas.
Hot dry climate with significant cooling load. Inland valleys shielded from marine influence. Typical locations: Irvine, Mission Viejo, Inland Empire lowlands, Orange County inland.
Hot dry climate. LA Basin inland areas with significant cooling load and moderate heating. Typical locations: Pasadena, Glendale, Burbank, Van Nuys, Woodland Hills.
Hot dry climate with extreme summer heat. Significant cooling load. Typical locations: Riverside, San Bernardino, Ontario, Fontana, Rancho Cucamonga.
Hot dry Sacramento Valley climate. Very hot summers, cool winters. Tule fog in winter. Typical locations: Red Bluff, Redding, Chico (Upper Sacramento Valley).
Hot moderate climate. Hot dry summers, cool damp winters. Tule fog Dec-Feb. Typical locations: Sacramento, Stockton, Modesto, Davis, Elk Grove.
Very hot dry San Joaquin Valley climate. Extreme summer heat, cool foggy winters. Highest cooling loads in California. Typical locations: Fresno, Bakersfield, Visalia, Merced.
Very hot desert climate with large diurnal swings. High altitude desert (2,500-3,500 ft). Cold winters possible. Typical locations: Palmdale, Lancaster, Mojave, Ridgecrest, China Lake.
Extreme hot desert climate. Below sea level in parts. Highest temperatures in California. Extreme cooling load. Typical locations: El Centro, Brawley, Calexico, Imperial (Imperial Valley).
Cold mountain climate with heavy snowfall. Highest heating loads in California. Ice barriers required. Typical locations: Mt. Shasta, Truckee, Big Bear, Lake Arrowhead, Blue Canyon, Mammoth Lakes.
Sample R-values and U-factors by climate zone
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| Zone | Edition | Component | R-Value | U-Factor | SHGC |
|---|---|---|---|---|---|
| CEC 4 | CRC 2022 | Ceiling Attic | R-30.0 | - | - |
| 4A | IRC 2021 | Ceiling Attic | R-49.0 | - | - |
| CEC 1 | CRC 2022 | Ceiling Attic | R-38.0 | - | - |
| 5A | IECC 2021 | Ceiling Attic |
| R-49.0 |
| - |
| - |
| CEC 10 | CRC 2022 | Ceiling Attic | R-30.0 | - | - |
| 1A | IECC 2021 | Ceiling Attic | R-30.0 | - | - |
| 6A | IRC 2018 | Ceiling Attic | R-54.0 | - | - |
| 8 | IRC 2018 | Ceiling Attic | R-59.0 | - | - |
| 5C | IECC 2021 | Ceiling Attic | R-49.0 | - | - |
| CEC 2 | CRC 2022 | Ceiling Attic | R-30.0 | - | - |
| CEC 5 | CRC 2022 | Ceiling Attic | R-30.0 | - | - |
| CEC 8 | CRC 2022 | Ceiling Attic | R-30.0 | - | - |
| CEC 14 | CRC 2022 | Ceiling Attic | R-38.0 | - | - |
| CEC 15 | CRC 2022 | Ceiling Attic | R-30.0 | - | - |
| 1 | IECC 2021 | Ceiling Attic | R-30.0 | - | - |
| 4C | IECC 2021 | Ceiling Attic | R-49.0 | - | - |
| 7 | IRC 2018 | Ceiling Attic | R-54.0 | - | - |
| 3A | IECC 2021 | Ceiling Attic | R-38.0 | - | - |
| 3C | IECC 2021 | Ceiling Attic | R-30.0 | - | - |
| 2B | IECC 2021 | Ceiling Attic | R-38.0 | - | - |
| 2A | IECC 2021 | Ceiling Attic | R-38.0 | - | - |
| 6A | IECC 2021 | Ceiling Attic | R-49.0 | - | - |
| 8 | IECC 2021 | Ceiling Attic | R-49.0 | - | - |
| 4A | IECC 2021 | Ceiling Attic | R-49.0 | - | - |
| 5B | IECC 2021 | Ceiling Attic | R-49.0 | - | - |
| 4B | IECC 2021 | Ceiling Attic | R-49.0 | - | - |
| CEC 11 | CRC 2022 | Ceiling Attic | R-38.0 | - | - |
| 3B | IECC 2021 | Ceiling Attic | R-38.0 | - | - |
| 7 | IECC 2021 | Ceiling Attic | R-49.0 | - | - |
| 5A | IRC 2021 | Ceiling Attic | R-49.0 | - | - |