Climate ZonesZone 2B

Climate Zone 2B: Hot - Dry

Hot, dry climate with extreme summer heat and low humidity. Cool winters with minimal heating requirements.

Load Characteristic
Cooling-Dominated
Moisture Regime
Dry
States Covered
4 States

ASHRAE Design Temperatures

Official design temperatures for Climate Zone 2B per ASHRAE Fundamentals 2021. These values are critical for accurate Manual J load calculations.

Winter Design Temp
31°F

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

Summer Design Temp
108°F

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

Wet Bulb Temp
71°F

Summer wet-bulb for latent cooling load and dehumidification calculations

2021 IECC Insulation Requirements

Minimum insulation and window specifications for Climate Zone 2B per the International Energy Conservation Code (IECC) 2021.

Wall Insulation
R-13

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

Roof/Ceiling Insulation
R-30

Minimum attic/ceiling R-value for energy compliance

Floor Insulation
R-13

Minimum floor R-value (over unconditioned space)

Window U-Factor
0.40

Maximum window U-factor (lower is better insulation)

Window SHGC
0.25

Maximum Solar Heat Gain Coefficient

Air Infiltration
0.25

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 2B installations.

Heating Systems

Gas furnace
Heat pump
Electric resistance
Typical AFUE
80-90%

Cooling Systems

AC (14-16 SEER)
Evaporative cooling (swamp cooler)
Typical SEER
14-16 SEER

States in Climate Zone 2B

Climate Zone 2B covers 4 states across the United States. Click a state to see city-specific climate data and Manual J load calculations.

Arizona
California
Nevada
Texas

Frequently Asked Questions About Climate Zone 2B

Q1What states are in Climate Zone 2B?

Climate Zone 2B includes parts of Arizona, California, Nevada, and Texas. This zone represents a cooling-dominated climate with dry moisture conditions.

Q2What are the design temperatures for Zone 2B?

The official ASHRAE design temperatures for Climate Zone 2B are:

  • Winter 99% Design Temp: 31°F
  • Summer 1% Design Temp: 108°F
  • Summer Wet Bulb: 71°F

Q3What equipment works best in Climate Zone 2B?

For Climate Zone 2B (Hot - Dry), recommended HVAC equipment includes:

Heating Systems:
  • • Gas furnace
  • • Heat pump
  • • Electric resistance

Typical AFUE: 80-90%

Cooling Systems:
  • • AC (14-16 SEER)
  • • Evaporative cooling (swamp cooler)

Typical SEER: 14-16 SEER

Q4What R-value insulation is required in Zone 2B?

IECC 2021 requires the following minimum R-values for Climate Zone 2B:

Walls
R-13
Roof
R-30
Floor
R-13
Window U
0.4

Q5Is Zone 2B heating-dominated or cooling-dominated?

Climate Zone 2B is cooling-dominated. This means cooling loads typically exceed heating loads, requiring greater focus on AC capacity, SEER ratings, and moisture control.

Q6What is the moisture regime for Zone 2B?

Zone 2B 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 2B

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