The formula to calculate BTUs from wattage, quantity, and efficiency is:

\[ BTUs = \sum \left( \frac{Wattage \times Quantity \times 3.41}{Efficiency} \right) \]

Where:

• \(BTUs\) is the British Thermal Units produced.
• \(Wattage\) is the power consumption in watts.
• \(Quantity\) is the number of units.
• \(Efficiency\) is the efficiency factor (default is 0.92).
• 3.41 is the conversion factor from watts to BTUs.