Climate ZonesZone 6A

Climate Zone 6A: Cold - Humid

Cold climate with very cold winters and warm summers. Very high heating loads, moderate cooling needs.

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

ASHRAE Design Temperatures

Official design temperatures for Climate Zone 6A per ASHRAE Fundamentals 2021. These values are critical for accurate Manual J load calculations.

Winter Design Temp
-9°F

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

Summer Design Temp
89°F

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

Wet Bulb Temp
73°F

Summer wet-bulb for latent cooling load and dehumidification calculations

2021 IECC Insulation Requirements

Minimum insulation and window specifications for Climate Zone 6A 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 6A installations.

Heating Systems

Gas furnace (96%+ AFUE)
Boiler
Cold climate heat pump
Typical AFUE
96-98%

Cooling Systems

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

States in Climate Zone 6A

Climate Zone 6A covers 12 states across the United States. Click a state to see city-specific climate data and Manual J load calculations.

Iowa
Maine
Massachusetts
Michigan
Minnesota
New Hampshire
New York
North Dakota
Pennsylvania
South Dakota
Vermont
Wisconsin

Frequently Asked Questions About Climate Zone 6A

Q1What states are in Climate Zone 6A?

Climate Zone 6A includes parts of Iowa, Maine, Massachusetts, Michigan, Minnesota, New Hampshire, New York, North Dakota, Pennsylvania, South Dakota, Vermont, and Wisconsin. This zone represents a heating-dominated climate with humid moisture conditions.

Q2What are the design temperatures for Zone 6A?

The official ASHRAE design temperatures for Climate Zone 6A are:

  • Winter 99% Design Temp: -9°F
  • Summer 1% Design Temp: 89°F
  • Summer Wet Bulb: 73°F

Q3What equipment works best in Climate Zone 6A?

For Climate Zone 6A (Cold - Humid), recommended HVAC equipment includes:

Heating Systems:
  • • Gas furnace (96%+ AFUE)
  • • Boiler
  • • Cold climate heat pump

Typical AFUE: 96-98%

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

Typical SEER: 13-15 SEER

Q4What R-value insulation is required in Zone 6A?

IECC 2021 requires the following minimum R-values for Climate Zone 6A:

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

Q5Is Zone 6A heating-dominated or cooling-dominated?

Climate Zone 6A 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 6A?

Zone 6A 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 6A

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