Piglets from birth to weaning were subjected to heat lamps with a constant output of 175W or a variable output from 175W at birth to 100W by weaning. Each output-type heat lamp had either clear or red-color radiant rays. The effects of the lamp output and color on piglet behavior and performance were evaluated at two air temperatures of 65 (±2)°F and 80 (±2)°F, respectively. The results indicate that the variable-output lamp is more suitable for swine farrowing operation. Compared with the constant-output lamp, the variable-output lamp would yield an annual energy savings of $29 (@$0.10/kWh and 88% of usage) while maintaining the same or somewhat improved piglet performance. The red-color rays showed no advantages over the clear rays with regards to piglet behavior and performance. Air temperature significantly affects heat lamp usage of the piglets. Development and application of an intelligent device to operate heat lamps based on the piglet’s need is warranted.