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Charles, Maryland HVAC Climate Zone

Charles is located in IECC Climate Zone 4A (Mixed - Humid). Get accurate Manual J load calculations with official design temperatures for Charles.

Climate Zone
4A
Winter Design
13°F
Summer Design
91°F
ZIP Codes
21

Charles HVAC Contractors: Get Your Free Manual J Report

Climate Zone 4A requires precise load calculations. Upload your Charles blueprint and get a professional Manual J report in 60 seconds— first report is FREE. Pre-loaded with Charles's exact design temperatures (13°F winter / 91°F summer).

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Verify Your Charles ZIP Code

Enter your ZIP code to confirm it's in Charles and get climate zone details.

Charles covers 21 ZIP codes: 20601, 20602, 20603, 20611, 20612, 20616, 20617, 20622, 20625, 20632 and 11 more

Charles Design Temperatures

Official ASHRAE design temperatures for Charles, used for accurate Manual J load calculations.

Winter 99% Design Temp
13°F
Summer 1% Design Temp
91°F
Summer Wet Bulb
75°F

IECC Requirements for Zone 4A

Minimum insulation and window requirements for Charles per IECC 2021.

Wall Insulation:R-20
Roof/Ceiling:R-49
Floor Insulation:R-19
Window U-Factor:0.32
Window SHGC:0.4

Energy Code: 2021 IECC

Recommended HVAC Equipment for Charles

Heating Systems

Gas furnace (90%+ AFUE)
Heat pump
Typical AFUE
92-96%

Cooling Systems

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

Related Climate Zone Pages

Learn More About
Climate Zone 4A
View All Zones in
Maryland
HVAC Permits for
Charles, Maryland

Get Free Manual J Calculations for Charles

Upload your Charles blueprint and get a professional Manual J load calculation using official Zone 4A design temperatures. First report is FREE.

Charles design temps
Zone 4A compliant
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