Climate ZonesZone 5A

Climate Zone 5A: Cool - Humid

Heating-dominated climate with cold winters and warm, humid summers. High heating loads, moderate cooling needs.

Load Characteristic
Heating-Dominated
Moisture Regime
Humid
States Covered
17 States

ASHRAE Design Temperatures

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

Winter Design Temp
0°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
75°F

Summer wet-bulb for latent cooling load and dehumidification calculations

2021 IECC Insulation Requirements

Minimum insulation and window specifications for Climate Zone 5A 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: 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 5A installations.

Heating Systems

Gas furnace (95%+ AFUE)
Boiler
Heat pump (cold climate)
Typical AFUE
95-98%

Cooling Systems

AC (13-16 SEER)
Heat pump
Typical SEER
13-16 SEER

States in Climate Zone 5A

Climate Zone 5A covers 17 states across the United States. Click a state to see city-specific climate data and Manual J load calculations.

Connecticut
Illinois
Indiana
Iowa
Kansas
Massachusetts
Michigan
Missouri
Nebraska
New Jersey
New York
Ohio
Pennsylvania
Rhode Island
South Dakota
West Virginia
Wisconsin

Frequently Asked Questions About Climate Zone 5A

Q1What states are in Climate Zone 5A?

Climate Zone 5A includes parts of Connecticut, Illinois, Indiana, Iowa, Kansas, Massachusetts, Michigan, Missouri, Nebraska, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, South Dakota, West Virginia, and Wisconsin. This zone represents a heating-dominated climate with humid moisture conditions.

Q2What are the design temperatures for Zone 5A?

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

  • Winter 99% Design Temp: 0°F
  • Summer 1% Design Temp: 91°F
  • Summer Wet Bulb: 75°F

Q3What equipment works best in Climate Zone 5A?

For Climate Zone 5A (Cool - Humid), recommended HVAC equipment includes:

Heating Systems:
  • • Gas furnace (95%+ AFUE)
  • • Boiler
  • • Heat pump (cold climate)

Typical AFUE: 95-98%

Cooling Systems:
  • • AC (13-16 SEER)
  • • Heat pump

Typical SEER: 13-16 SEER

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

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

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

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

Climate Zone 5A 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 5A?

Zone 5A 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 5A

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