Understanding Internal Electric Load: The Hidden Power Consumers in Buildings

Internal electric load refers to the total amount of electrical energy consumed by devices, appliances, lighting, and systems within a building. Unlike external loads like HVAC or outdoor lighting, internal loads directly impact energy consumption, electrical design, and building performance.

What Is Internal Electric Load?

Internal electric load includes all power-consuming equipment inside a building, such as:

• Lighting fixtures
• Office equipment (computers, printers, servers)
• Kitchen appliances (microwaves, refrigerators, dishwashers)
• Plug loads (chargers, fans, power tools)
• Elevators and escalators
• Data centers and communication systems

These loads are essential for everyday operations but also contribute to heat gain, increasing cooling demands and overall energy use.

Why Internal Load Matters

1. Electrical Design: Accurately estimating internal loads ensures proper sizing of wiring, panels, and transformers.
2. Energy Efficiency: High internal loads can increase energy consumption and affect building energy ratings.
3. Thermal Impact: Internal loads release heat, which affects HVAC system sizing and performance.
4. Load Management: Helps identify opportunities for demand-side energy management and automation.

Calculating Internal Load (Basic Steps):

1. Identify All Internal Equipment: List every device and appliance inside the building.
2. Determine Power Ratings: Use nameplate data (watts/kW) or manufacturer specifications.
3. Estimate Usage Hours: Calculate daily or peak-time usage to determine energy consumption (kWh).
4. Apply Diversity Factor: Not all devices run at the same time; applying diversity gives a realistic load estimate.
5. Add Loads: Total up all individual internal loads to get the full internal electric load.

Strategies to Reduce Internal Load:

• Use LED lighting instead of incandescent or fluorescent
• Install smart power strips and occupancy sensors
• Upgrade to energy-efficient appliances and office equipment
• Implement automated controls to manage plug loads during non-peak hours

Conclusion

Internal electric load plays a crucial role in the energy performance of any building. Whether designing a new facility or upgrading an existing one, understanding and managing internal loads can lead to better system design, lower utility bills, and a more sustainable operation.