Cost

• Lighting costs consist of two main elements: the initial cost of the equipment and the running costs. LED bulbs use fewer amps than their incandescent equivalents and therefore cost less to run, but a new incandescent unit costs less to buy. If a light is illuminated for sufficient hours, lower running costs may compensate for higher initial costs.
  
  

Durability

• The lifespan of an incandescent bulb is estimated at several thousand hours at most. LED manufacturers make claims of lifespans running to 100,000 hours, but research commissioned by the U.S. Department of Energy suggests that these claims may be greatly exaggerated.
  
  

Weight and Size

• LED light units are often marketed as being compatible with existing incandescent light fittings. While this is generally true, U.S government research has shown that LED units are often heavier and have thicker bases than their incandescent equivalents. This may influence the design of a new lighting system.