1. What are Heating Degree Days (HDD)?

Definition: HDD is a measurement designed to quantify the demand for energy needed to heat a building. It's the sum of degrees that a day's average temperature is below a base temperature.

Purpose: Used by energy companies, HVAC professionals, and researchers to estimate heating requirements and energy consumption.

2. How Does the HDD Calculator Work?

The calculator uses the formula:

Where:

• \( \text{Base Temp} \) — Reference temperature (typically 65°F in the US)
• \( \text{Daily Avg Temp} \) — (High Temp + Low Temp)/2 for each day
• \( \max(0, x) \) — Only positive differences are counted

Explanation: For each day, if the average temperature is below the base temperature, the difference is added to the HDD total.

3. Importance of HDD Calculation

Details: HDD helps in:

• Estimating seasonal heating requirements
• Comparing energy use across different periods
• Designing HVAC systems
• Energy consumption forecasting

4. Using the Calculator

Tips:

• Enter the base temperature (default 65°F)
• Enter comma-separated daily average temperatures (e.g., "45, 48, 52, 47")
• The calculator sums all positive differences between base and daily temps

5. Frequently Asked Questions (FAQ)

Q1: Why is 65°F commonly used as the base temperature?
A: This was established as the temperature at which buildings typically need no additional heating.

Q2: Can I use different base temperatures?
A: Yes, some calculations use 60°F or other values depending on building insulation and local climate.

Q3: How do I get daily average temperatures?
A: Average the daily high and low temperatures, or use weather station data.

Q4: What's the difference between HDD and CDD?
A: CDD (Cooling Degree Days) measures cooling demand when temperatures are above the base.

Q5: How are HDD used in energy billing?
A: Utility companies may use HDD to normalize bills and compare usage across different weather conditions.