The Cooling Degree Hours (CDH) Calculator measures the total degree-hours above a specified base temperature over a given period, typically one day. It provides detailed insights into cooling demands, allowing individuals and businesses to assess the hourly cooling requirements more accurately compared to daily metrics like Cooling Degree Days.
This calculator is particularly useful for energy analysts, HVAC professionals, and utility companies aiming to optimize cooling systems, forecast energy consumption, and reduce costs.
Formula of Cooling Degree Hours Calculator
The formula for calculating Cooling Degree Hours is:
Cooling Degree Hours = Σ (Hourly Temperature – Base Temperature) for each hour where Hourly Temperature > Base Temperature
Detailed Formula Components:
- Hourly Temperature: The recorded temperature for each hour during the day, measured in consistent units such as Fahrenheit (°F) or Celsius (°C).
- Base Temperature: The threshold temperature above which cooling becomes necessary, typically set at 65°F (18°C) unless specified otherwise.
- Cooling Degree Hours (CDH): The cumulative number of degrees above the base temperature for each hour during the specified period.
Key Notes:
- If the hourly temperature is less than or equal to the base temperature, that hour does not contribute to the CDH value.
- CDH provides a more granular understanding of cooling needs compared to Cooling Degree Days.
Pre-Calculated Values Table
This table provides estimated Cooling Degree Hours for various temperature scenarios over a 12-hour period:
| Hour | Hourly Temp (°F) | Base Temp (°F) | Degrees Above Base | Cumulative CDH |
|---|---|---|---|---|
| 1 | 72 | 65 | 7 | 7 |
| 2 | 74 | 65 | 9 | 16 |
| 3 | 76 | 65 | 11 | 27 |
| 4 | 78 | 65 | 13 | 40 |
| 5 | 80 | 65 | 15 | 55 |
| 6 | 79 | 65 | 14 | 69 |
| 7 | 77 | 65 | 12 | 81 |
| 8 | 75 | 65 | 10 | 91 |
| 9 | 73 | 65 | 8 | 99 |
| 10 | 71 | 65 | 6 | 105 |
| 11 | 70 | 65 | 5 | 110 |
| 12 | 68 | 65 | 3 | 113 |
Example of Cooling Degree Hours Calculator
Scenario:
A location experiences the following hourly temperatures: 70°F, 72°F, 74°F, 76°F, and 78°F over a 5-hour period. The base temperature is set at 65°F. Calculate the Cooling Degree Hours.
Step-by-Step Solution:
- Calculate Degrees Above Base for Each Hour:
- Hour 1: 70 – 65 = 5
- Hour 2: 72 – 65 = 7
- Hour 3: 74 – 65 = 9
- Hour 4: 76 – 65 = 11
- Hour 5: 78 – 65 = 13
- Sum the Degrees Above Base:
Cooling Degree Hours = 5 + 7 + 9 + 11 + 13 = 45
Result:
The total Cooling Degree Hours for the 5-hour period is 45.
Most Common FAQs
Cooling Degree Hours provides a more detailed view by analyzing hourly temperature data, whereas Cooling Degree Days aggregates daily average temperatures. CDH is better for understanding short-term cooling needs.
Yes, the base temperature can be adjusted to match specific cooling thresholds for industrial or residential settings.
CDH is commonly used for energy management, optimizing HVAC systems, planning utility loads, and analyzing climate patterns for cooling requirements.