Real power is the actual electrical power consumed by HVAC equipment to perform useful work such as cooling, heating, and fan operation, measured in watts. Unlike reactive power which oscillates without producing work, real power directly delivers energy to accomplish the system’s intended function. Real power forms the basis for utility billing and energy cost calculations.
Technical Details
Real power is calculated as voltage multiplied by current multiplied by the power factor (P = V × I × PF). It represents the in-phase component of AC power that produces actual cooling or heating output. A 240-volt air conditioning system drawing 20 amperes at 0.85 power factor consumes 4,080 watts of real power. Real power is measured in watts or kilowatts and appears on utility bills as the basis for consumption charges.
HVAC Applications
Real power consumption determines HVAC system operating costs and energy efficiency ratings. A 5-kilowatt system running continuously for 1 hour consumes 5 kilowatt-hours. Manufacturers rate equipment efficiency by comparing cooling output to real power input, expressed as coefficient of performance or SEER ratings.
System Design and Management
Sizing HVAC systems requires calculating real power demand to ensure adequate electrical service capacity. Energy audits focus on real power consumption to identify efficiency opportunities and calculate payback periods for upgrades.