How To Calculate Cooling Degree Hours

Cooling Degree Hours Formula:

\[ CDH = \sum \max(0, \text{Hourly Avg Temp} - \text{Base Temp}) \]

Cooling Degree Hours (CDH):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What Are Cooling Degree Hours?

Cooling Degree Hours (CDH) measure the amount of cooling required for a building based on outdoor temperature. They represent the accumulated temperature difference above a base temperature over time, typically calculated hourly.

2. How Does The Calculator Work?

The calculator uses the Cooling Degree Hours formula:

\[ CDH = \sum \max(0, \text{Hourly Avg Temp} - \text{Base Temp}) \]

Where:

\( \text{Hourly Avg Temp} \) — Average temperature for the hour (°F)
\( \text{Base Temp} \) — Reference base temperature (°F)
\( \max(0, x) \) — Returns zero if temperature difference is negative

Explanation: The formula calculates the temperature difference above the base temperature for each hour, summing only positive values to determine total cooling requirements.

3. Importance Of CDH Calculation

Details: Cooling Degree Hours are essential for HVAC system design, energy consumption estimation, load calculations, and optimizing building energy efficiency. They help predict cooling demands and size appropriate cooling systems.

4. Using The Calculator

Tips: Enter hourly average temperature and base temperature in degrees Fahrenheit. The calculator will compute the cooling degree hours for that specific hour. For daily or monthly calculations, sum individual hourly CDH values.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical base temperature for CDH calculations?
A: Common base temperatures range from 65°F to 75°F, with 65°F being most standard for residential applications.

Q2: How do CDH differ from Cooling Degree Days?
A: CDH provide hourly resolution while CDD provide daily averages. CDH offer more precise data for systems with variable loads throughout the day.

Q3: When are Cooling Degree Hours most useful?
A: They're particularly valuable for commercial buildings, data centers, and facilities with 24/7 operations where cooling needs vary significantly by hour.

Q4: Can CDH be used for energy billing analysis?
A: Yes, CDH correlate well with cooling energy consumption and can help analyze utility bills and identify energy efficiency opportunities.

Q5: How do I calculate monthly CDH?
A: Sum the CDH values for all hours in the month. Most weather services provide hourly temperature data for these calculations.