According to NFPA 13, the selection of a sprinkler's temperature classification is based on the maximum anticipated ceiling temperature in the area of installation. This ensures a safe temperature differential to prevent accidental activation under normal conditions. For a maximum ceiling temperature of 80°F (26°C), which is below the 100°F (38°C) threshold specified in the standard, the lowest permissible temperature classification is "Ordinary." This classification corresponds to sprinklers with an activation temperature rating between 135°F and 170°F (57°C and 77°C), providing an adequate safety margin.

B. High: This classification is required for much higher maximum ceiling temperatures, specifically those between 151°F and 225°F (66°C and 107°C).

C. Intermediate: This classification is used for areas where the maximum ceiling temperature is between 101°F and 150°F (39°C and 65°C).

D. Extra high: This classification is designated for environments with very high ambient temperatures, where the maximum ceiling temperature is between 226°F and 300°F (108°C and 149°C).

1. NFPA 13, Standard for the Installation of Sprinkler Systems (2022 Edition). Table 7.2.4.1, "Temperature Ratings, Classifications, and Color Codings." The first row of this table explicitly states that for a "Maximum Ceiling Temperature" of 100°F (38°C) or less, the required "Temperature Classification" is Ordinary.

2. SFPE Handbook of Fire Protection Engineering, 5th Edition. Chapter 21, "Automatic Sprinkler Systems," Section 21.4.1.1, "Temperature Rating." This section discusses the principles of sprinkler temperature selection and directly references the NFPA 13 requirements, stating, "The ordinary-temperature-rated sprinkler is the most common and is used where the maximum ambient ceiling temperature does not exceed 100°F (38°C)." (DOI: https://doi.org/10.1007/978-1-4939-2562-421)

3. Worcester Polytechnic Institute (WPI), Fire Protection Engineering Program Courseware. FPE 571, Fire Protection Systems. Course materials on sprinkler design specify that temperature selection must follow NFPA 13, Table 7.2.4.1 (in the 2022 edition), reinforcing that ordinary-rated sprinklers are used for maximum ceiling temperatures up to 100°F.