Heat

• According to the U.S. Department of Energy, the standard low-voltage incandescent bulb is the MR16 quartz-halogen bulb. In consumer tests, the Department found that halogen MR16 lamps produced far more heat than the equivalent LED lights. In normal use, around 90 percent of the energy used by halogen lights became heat, not light. Some halogen bulbs reached temperatures in excess of 392 degrees Fahrenheit.
  
  

Dimming

• Normal dimmer switches are designed to work well with incandescent bulbs. When a dimmer switch reduces the power to the bulb, the filament glows less brightly and takes on a warmer and more orange glow as it is dimmed. LED lights do not significantly change color as they are dimmed, and they require special dimmer switches. Rather than acquiring an orange tint, dimmed LEDs may produce a bluer, colder looking light.
  
  

Bulb Lifetime

• The lifetime of incandescent lights is well researched and based on observational testing as well as theoretical work. Research has shown that the claims for hugely extended lifetimes for LED lamps may be misleading. According to the U.S. Department of Energy, the long-term performance of LED lamps is still a "great unknown."