Climate ZonesZone 3B

Climate Zone 3B: Warm - Dry

Warm climate with low humidity, hot summers and cool winters. Moderate heating and cooling loads.

Load Characteristic
Balanced Loads
Moisture Regime
Dry
States Covered
5 States

ASHRAE Design Temperatures

Official design temperatures for Climate Zone 3B per ASHRAE Fundamentals 2021. These values are critical for accurate Manual J load calculations.

Winter Design Temp
35°F

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

Summer Design Temp
99°F

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

Wet Bulb Temp
68°F

Summer wet-bulb for latent cooling load and dehumidification calculations

2021 IECC Insulation Requirements

Minimum insulation and window specifications for Climate Zone 3B 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-30

Minimum attic/ceiling R-value for energy compliance

Floor Insulation
R-19

Minimum floor R-value (over unconditioned space)

Window U-Factor
0.32

Maximum window U-factor (lower is better insulation)

Window SHGC
0.25

Maximum 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 3B installations.

Heating Systems

Gas furnace
Heat pump
Typical AFUE
90-95%

Cooling Systems

AC (14-16 SEER)
Typical SEER
14-16 SEER

States in Climate Zone 3B

Climate Zone 3B covers 5 states across the United States. Click a state to see city-specific climate data and Manual J load calculations.

Arizona
California
Nevada
New Mexico
Texas

Frequently Asked Questions About Climate Zone 3B

Q1What states are in Climate Zone 3B?

Climate Zone 3B includes parts of Arizona, California, Nevada, New Mexico, and Texas. This zone represents a balanced climate with dry moisture conditions.

Q2What are the design temperatures for Zone 3B?

The official ASHRAE design temperatures for Climate Zone 3B are:

  • Winter 99% Design Temp: 35°F
  • Summer 1% Design Temp: 99°F
  • Summer Wet Bulb: 68°F

Q3What equipment works best in Climate Zone 3B?

For Climate Zone 3B (Warm - Dry), recommended HVAC equipment includes:

Heating Systems:
  • • Gas furnace
  • • Heat pump

Typical AFUE: 90-95%

Cooling Systems:
  • • AC (14-16 SEER)

Typical SEER: 14-16 SEER

Q4What R-value insulation is required in Zone 3B?

IECC 2021 requires the following minimum R-values for Climate Zone 3B:

Walls
R-20
Roof
R-30
Floor
R-19
Window U
0.32

Q5Is Zone 3B heating-dominated or cooling-dominated?

Climate Zone 3B is a balanced climate. This means heating and cooling loads are relatively balanced, requiring careful sizing of both heating and cooling equipment.

Q6What is the moisture regime for Zone 3B?

Zone 3B 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 3B

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