CRI

Every light bulb has a unique ability to represent color in objects. This is known as its CRI or color rendering index. CRI is a critical factor in selecting the right lamp for each application.
It is measured on a scale of 0-100. The higher the CRI, the more vibrant the colors appear. A 100 CRI indicates that the lamp will render 100% of the true color in the illuminant. Light from lamps with a good (70-80 CRI) and an excellent (80+ CRI) color rendering properties are considered high quality because objects and people look more appealing and the light level itself is perceived to be higher.

Color Temperature

The overall color appearance of the light that comes from a light source is called color temperature. Also referred to as chromaticity (CCT) and is measured in degrees Kelvin or K. Color temperature creates the mood or ambiance of the space and can influence shopping behavior, work performance, sense of security and general well being. Color temperature typically starts with a 2700K warm appearance and can reach 5000K, which is daylight. The higher the degrees Kelvin, the cooler and crisper the color appearance.

Energy

Typically, only 10% -15% of the energy consumed by a halogen lamp produces visible light. The remainder is lost as heat. So, a 50W MR16 consumes 50W of energy, but only 5-10W produce light, the remaining 40-45W is just hot air. The cost of electricity is approximately 86% of total lighting costs in terms of lifecycle. The lifecycle costs can be reduced by using energy efficient lamps such as fluorescent, metal halide and HIR lamps.

Compact Fluorescent Lamps and Dimming

In order to dim a compact fluorescent lamp, the lamp must be a 4 pin base. CFLs with a 2 pin base cannot be dimmed.