Climate ZonesZone 2A

Climate Zone 2A: Hot - Humid

Cooling-dominated with hot, humid summers and mild winters. Significant cooling loads with moderate heating needs.

Load Characteristic
Cooling-Dominated
Moisture Regime
Humid
States Covered
7 States

ASHRAE Design Temperatures

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

Winter Design Temp
32°F

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

Summer Design Temp
95°F

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

Wet Bulb Temp
77°F

Summer wet-bulb for latent cooling load and dehumidification calculations

2021 IECC Insulation Requirements

Minimum insulation and window specifications for Climate Zone 2A 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: Humid

High humidity climate requiring significant moisture control

Key Considerations for Humid Climates:

  • High dehumidification loads
  • Mold/mildew prevention critical
  • Proper vapor barriers essential

Recommended HVAC Equipment

Typical equipment specifications for Climate Zone 2A installations.

Heating Systems

Gas furnace
Heat pump
Electric resistance
Typical AFUE
80-92%

Cooling Systems

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

States in Climate Zone 2A

Climate Zone 2A covers 7 states across the United States. Click a state to see city-specific climate data and Manual J load calculations.

Alabama
Florida
Georgia
Louisiana
Mississippi
South Carolina
Texas

Frequently Asked Questions About Climate Zone 2A

Q1What states are in Climate Zone 2A?

Climate Zone 2A includes parts of Alabama, Florida, Georgia, Louisiana, Mississippi, South Carolina, and Texas. This zone represents a cooling-dominated climate with humid moisture conditions.

Q2What are the design temperatures for Zone 2A?

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

  • Winter 99% Design Temp: 32°F
  • Summer 1% Design Temp: 95°F
  • Summer Wet Bulb: 77°F

Q3What equipment works best in Climate Zone 2A?

For Climate Zone 2A (Hot - Humid), recommended HVAC equipment includes:

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

Typical AFUE: 80-92%

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

Typical SEER: 14-16 SEER

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

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

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

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

Climate Zone 2A 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 2A?

Zone 2A has a humid moisture regime. This means high humidity levels, significant dehumidification requirements in summer, and careful attention to latent cooling loads in Manual J calculations.

Get Accurate Load Calculations for Zone 2A

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