1. What is BTU/h Load Calculation?

BTU/h (British Thermal Units per hour) load calculation determines the cooling capacity needed for a space. It accounts for heat transfer through building envelope, occupant heat gain, and equipment heat generation.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• \( Area \) — Floor area in square feet
• \( Height \) — Ceiling height in feet
• \( \Delta T \) — Temperature difference between inside and outside (°F)
• \( U \) — U-value of building envelope (BTU/(h·ft²·°F))
• \( Occupants \) — Number of people in the space
• \( Equipment \) — Electrical equipment wattage

Explanation: The calculation combines envelope heat transfer (conduction), occupant heat gain (metabolic), and equipment heat gain (electrical).

3. Importance of Load Calculation

Details: Proper load calculation ensures HVAC systems are correctly sized - preventing energy waste from oversized systems or inadequate cooling from undersized systems.

4. Using the Calculator

Tips: Measure your space accurately. For ΔT, use design temperature difference (typically 20-25°F for cooling). U-values range from 0.05 (well-insulated) to 1.0 (poor insulation).

5. Frequently Asked Questions (FAQ)

Q1: What's a typical U-value for residential walls?
A: Modern insulated walls typically have U-values between 0.05-0.25 BTU/(h·ft²·°F).

Q2: How much heat does a person generate?
A: About 600 BTU/h per person at rest, up to 1,000 BTU/h for light activity.

Q3: What's the conversion from watts to BTU/h?
A: 1 watt = 3.412 BTU/h (exact conversion factor).

Q4: Should I add a safety factor?
A: This calculation provides design load. HVAC professionals often add 10-20% safety factor.

Q5: How does window area affect the calculation?
A: Windows typically have higher U-values. For accuracy, calculate windows separately with their own U-values.