ASHRAE-90.1-2022- - Page 463
Extracted Content
SECTION ANNEX1-1 ASHRAE STANDARD 169-2013, SECTION A3: CLIMATE ZONE DEFINITIONS
A3. CLIMATE ZONE DEFINITIONS
To determine the climate zones for locations not listed in this standard, use the following information to determine climate zone numbers and letters.
Determine the thermal climate zone, 0–8, from Table A-3, using the heating and cooling degree-days for the location.
Determine the moisture zone (Marine, Dry or Humid):
a. If monthly average temperature and precipitation data are available, use the Marine, Dry, and Humid
definitions below to determine the moisture zone (C, B, or A). b. If annual average temperature information (including degree-days) and annual precipitation (i.e. annual
mean) are available, use the following to determine the moisture zone:
- If thermal climate zone is 3 and CDD50°F 4500 (CDD10°C 2500), climate zone is Marine (3C).
- If thermal climate zone is 4 and CDD50°F 2700 (CDD10°C 1500), climate zone is Marine (4C).
- If thermal climate zone is 5 and CDD50°F 1800 (CDD10°C 1000), climate zone is Marine (5C).
Use the the third criteria below for determining the Dry/Humid threshold if not Marine (C).
c. If only degree-day information is available, use the following to determine the moisture zone:
- If thermal climate zone is 3 and CDD50°F 4500 (CDD10°C 2500), climate zone is Marine (3C).
- If thermal climate zone is 4 and CDD50°F 2700 (CDD10°C 1500), climate zone is Marine (4C).
- If thermal climate zone is 5 and CDD50°F 1800 (CDD10°C 1000), climate zone is Marine (5C) .
It is not possible to assign Dry/Humid splits in this case.
Marine (C) Zone Definition —Locations meeting all four of the following criteria:
a. Mean temperature of coldest month between 27°F (–3°C) and 65°F (18°C) b. Warmest month mean < 72°F (22°C) c. At least four months with mean temperatures over 50°F (10°C) d. Dry season in summer. The month with the heaviest precipitation in the cold season has at least three
times as much precipitation as the month with the least precipitation in the rest of the year. The cold season is October through March in the Northern Hemisphere and April through September in the Southern Hemisphere.
Dry (B) Definition —Locations meeting the following criteria:
a. Not Marine (C) b. If 70% or more of the precipitation, P, occurs during the high sun period, then the dry/humid threshold is
P < 0.44 × ( T - 7) (I-P) P < 20.0 × ( T + 14) (SI) c. If between 30% and 70% of the precipitation, P, occurs during the high sun period, then the dry/humid
threshold is
P < 0.44 × ( T - 19.5) (I-P) P < 20.0 × ( T + 7) (SI) d. If 30% or less of the precipitation, P, occurs during the high sun period, then the dry/humid threshold is
P < 0.44 × ( T - 32) (I-P) P < 20 × T (SI) where
P = annual precipitation, in. (mm)
T = annual mean temperature, °F (°C)
Summer or high sun period = April through September in the Northern Hemisphere and October through March in the Southern Hemisphere
Winter or cold season = October through March in the Northern Hemisphere and April through September in the Southern Hemisphere
Humid (A) Definition —Locations that are not Marine (C) and not Dry (B)
ANSI/ASHRAE/IES Standard 90.1-2022 (I-P) 461