Climate ZonesZone 5B

Climate Zone 5B: Cool - Dry

Heating-dominated with cold, dry winters and warm summers. High heating loads in winter, moderate cooling needs.

Load Characteristic
Heating-Dominated
Moisture Regime
Dry
States Covered
9 States

ASHRAE Design Temperatures

Official design temperatures for Climate Zone 5B per ASHRAE Fundamentals 2021. These values are critical for accurate Manual J load calculations.

Winter Design Temp
-7°F

99% design temperature for heating load calculations (coldest expected temperature)

Summer Design Temp
91°F

1% design temperature for cooling load calculations (hottest expected temperature)

Wet Bulb Temp
63°F

Summer wet-bulb for latent cooling load and dehumidification calculations

2021 IECC Insulation Requirements

Minimum insulation and window specifications for Climate Zone 5B per the International Energy Conservation Code (IECC) 2021.

Wall Insulation
R-20

Minimum wall R-value (continuous insulation or cavity + continuous)

Roof/Ceiling Insulation
R-49

Minimum attic/ceiling R-value for energy compliance

Floor Insulation
R-30

Minimum floor R-value (over unconditioned space)

Window U-Factor
0.30

Maximum window U-factor (lower is better insulation)

Window SHGC
0.40

Recommended Solar Heat Gain Coefficient

Air Infiltration
0.15

Typical ACH (air changes per hour) for load calculations

Moisture Regime: Dry

Low humidity climate with minimal moisture concerns

Key Considerations for Dry Climates:

  • Minimal dehumidification needed
  • Focus on proper humidification in winter
  • Lower infiltration moisture loads

Recommended HVAC Equipment

Typical equipment specifications for Climate Zone 5B installations.

Heating Systems

Gas furnace (95%+ AFUE)
Typical AFUE
95-98%

Cooling Systems

AC (13-15 SEER)
Typical SEER
13-15 SEER

States in Climate Zone 5B

Climate Zone 5B covers 9 states across the United States. Click a state to see city-specific climate data and Manual J load calculations.

Colorado
Idaho
Montana
Nevada
New Mexico
Oregon
Utah
Washington
Wyoming

Frequently Asked Questions About Climate Zone 5B

Q1What states are in Climate Zone 5B?

Climate Zone 5B includes parts of Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming. This zone represents a heating-dominated climate with dry moisture conditions.

Q2What are the design temperatures for Zone 5B?

The official ASHRAE design temperatures for Climate Zone 5B are:

  • Winter 99% Design Temp: -7°F
  • Summer 1% Design Temp: 91°F
  • Summer Wet Bulb: 63°F

Q3What equipment works best in Climate Zone 5B?

For Climate Zone 5B (Cool - Dry), recommended HVAC equipment includes:

Heating Systems:
  • • Gas furnace (95%+ AFUE)

Typical AFUE: 95-98%

Cooling Systems:
  • • AC (13-15 SEER)

Typical SEER: 13-15 SEER

Q4What R-value insulation is required in Zone 5B?

IECC 2021 requires the following minimum R-values for Climate Zone 5B:

Walls
R-20
Roof
R-49
Floor
R-30
Window U
0.3

Q5Is Zone 5B heating-dominated or cooling-dominated?

Climate Zone 5B is heating-dominated. This means heating loads typically exceed cooling loads, requiring greater focus on furnace capacity and winter insulation values.

Q6What is the moisture regime for Zone 5B?

Zone 5B has a dry moisture regime. This means low humidity levels, minimal dehumidification requirements, and focus on proper winter humidification to prevent dry air issues.

Get Accurate Load Calculations for Zone 5B

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