To determine the required capacity of heating or cooling equipment for a structure, which calculation should be performed?

• A. Thermal Mass Analysis
• B. Heat Load Calculation
• C. Solar Gain Assessment
• D. Energy Use Index

Answer: (B)

Sizing heating or cooling equipment comes down to calculating the building’s heat load—the total amount of heat that must be added or removed to keep indoor conditions at the set temperature under design conditions. A heat load calculation combines factors like outdoor design temperatures, envelope properties (insulation, windows, air leaks), internal gains from occupants, equipment, and lighting, ventilation and infiltration, and any solar gains. The result is a capacity value in BTU per hour or kilowatts that guides selecting equipment with the right size and a sensible safety margin. Other concepts touch on related ideas but don’t yield the full instantaneous load needed for proper equipment sizing: thermal mass analysis looks at how building mass affects temperature swings, solar gain assessment estimates solar contributions, and the energy use index reflects annual energy performance rather than peak heating or cooling requirements.