Table C301.1 shall be used in determining the applicable requirements from Chapter 4. Locations are assigned a climate zone based on Section C301.3.
Figure C301.1 Climate Zone.
CLIMATE ZONES, MOISTURE REGIMES, AND WARM-HUMID DESIGNATIONS BY COUNTY
|Key: A – Moist |
Asterisk (*) indicates a warm-humid location.
|2A Indian River*|
|1A Palm Beach*|
|2A Santa Rosa*|
|2A St. Johns*|
|2A St. Lucie*|
The climate zone for any location outside the United States shall be determined by applying Table C301.3(1) and then Table C301.3(2).
INTERNATIONAL CLIMATE ZONE DEFINITIONS
|MAJOR CLIMATE TYPE DEFINITIONS|
|Marine (C) Definition—Locations meeting all four criteria: |
|Dry (B) Definition—Locations meeting the following criteria:|
|Not marine and Pin < 0.44 × (TF - 19.5) [Pcm < 2.0 × (TC + 7) in SI units]|
Pin = Annual precipitation in inches (cm)
T = Annual mean temperature in °F (°C)
|Moist (A) Definition—Locations that are not marine and not dry.|
|Warm-humid Definition—Moist (A) locations where either of the following wet-bulb temperature conditions shall occur during the warmest six consecutive months of the year: |
For SI: °C = [(°F) - 32]/1.8, 1 inch = 2.54 cm.
INTERNATIONAL CLIMATE ZONE DEFINITIONS
|IP Units||SI Units|
|1||9000 < CDD50°F||5000 < CDD10°C|
|2||6300 < CDD50°F ≤ 9000||3500 < CDD10°C ≤ 5000|
|3A and 3B||4500 < CDD50°F ≤ 6300 AND HDD65°F ≤ 5400||2500 < CDD10°C ≤ 3500 AND HDD18°C ≤ 3000|
|4A and 4B||CDD50°F ≤ 4500 AND HDD65°F ≤ 5400||CDD10°C ≤ 2500 AND HDD18°C ≤ 3000|
|3C||HDD65°F ≤ 3600||HDD18°C ≤ 2000|
|4C||3600 < HDD65°F ≤ 5400||2000 < HDD18°C ≤ 3000|
|5||5400 < HDD65°F ≤ 7200||3000 < HDD18°C ≤ 4000|
|6||7200 < HDD65°F ≤ 9000||4000 < HDD18°C ≤ 5000|
|7||9000 < HDD65°F ≤ 12600||5000 < HDD18°C ≤ 7000|
|8||12600 < HDD65°F||7000 < HDD18°C|
For SI: °C = [(°F) - 32]/1.8.
The tropical climate zone shall be defined as:
- Hawaii, Puerto Rico, Guam, American Samoa, U.S. Virgin Islands, Commonwealth of Northern Mariana Islands; and
- Islands in the area between the Tropic of Cancer and the Tropic of Capricorn.
U-factors of fenestration products (windows, doors and skylights) shall be determined in accordance with NFRC 100.
Exception: Where required, garage door U-factors shall be determined in accordance with either NFRC 100 or ANSI/DASMA 105.
U-factors shall be determined by an accredited, independent laboratory, and labeled and certified by the manufacturer.
Products lacking such a labeled U-factor shall be assigned a default U-factor from Table C303.1.3(1) or C303.1.3(2). The solar heat gain coefficient (SHGC) and visible transmittance (VT) of glazed fenestration products (windows, glazed doors and skylights) shall be determined in accordance with NFRC 200 by an accredited, independent laboratory, and labeled and certified by the manufacturer. Products lacking such a labeled SHGC or VT shall be assigned a default SHGC or VT from Table C303.1.3(3).
DEFAULT GLAZED FENESTRATION U-FACTORS
|FRAME TYPE||SINGLE |
|Metal with Thermal Break||1.10||0.65||1.90||1.10|
|Nonmetal or Metal Clad||0.95||0.55||1.75||1.05|
DEFAULT DOOR U-FACTORS
|Insulated, nonmetal edge, max 45% glazing, |
any glazing double pane
DEFAULT GLAZED FENESTRATION SHGC AND VT
|SINGLE GLAZED||DOUBLE GLAZED||GLAZED |
R-values for building materials used to demonstrate code compliance with Chapter C4 shall be taken from ASHRAE 90.1 Normative Appendix A, from manufacturer’s product literature or from other nationally recognized engineering sources. Assembly U-factor calculations shall follow the procedure(s) detailed in Section C304.3 or be tested in accordance with procedure(s) described in Section C304.2.
Concrete block R-values shall be calculated using the isothermal planes method or a two-dimensional calculation program, thermal conductivities from ASHRAE 90.1 Normative Appendix A and dimensions from ASTM C90. The parallel path calculation method is not acceptable.
Exception: R-values for building materials or thermal conductivities determined from testing in accordance with Section C304.2.
If building material R-values or thermal conductivities are determined by testing, one of the following test procedures shall be used:
- ASTM C177
- ASTM C236
- ASTM C518
For concrete, the oven-dried conductivity shall be multiplied by 1.2 to reflect the moisture content as typically installed.
Prescribed R-values for air films shall be as follows:
|0.17||All exterior surfaces|
|0.46||All semi-exterior surfaces|
|0.61||Interior horizontal surfaces, heat flow up|
|0.92||Interior horizontal surfaces, heat flow down|
|0.68||Interior vertical surfaces|
If the building official determines that the proposed construction assembly is not adequately represented in the appropriate table of ASHRAE 90.1 Normative Appendix A, the applicant shall determine appropriate values for the assembly using the assumptions in ASHRAE 90.1 Normative Appendix A. An assembly is deemed to be adequately represented if:
- the interior structure, hereafter referred to as the base assembly, for the class of construction is the same as described in Normative Appendix A and
- changes in exterior or interior surface building materials added to the base assembly do not increase or decrease the R-value by more than 2 from that indicated in the descriptions in ASHRAE 90.1 Normative Appendix A.
Insulation, including insulated sheathing, is not considered a building material.