LIGHTING DESIGN LECTURE 6Efficient Electric Light Sources

•Remember our basic concerns about light sources• Generally designed to provide two things

•Accurate rendition of color / complete spectrum (Color Rendering Index from 0-100)•Pleasing color temperature / balance of spectrum (Degrees / Kelvins)

•The attributes to consider•Initial cost•Operating cost•Color rendering index•Color temperature•Ballast and transformer req.•Dimming•Instant on / off•Directionality•Efficacy•Lamp life•Temperature requirements•Heat generated•Noise

Fluorescent, HID and LED’s are generally considered “high-efficiency” electric light sources

LIGHTING DESIGN LECTURE 6Efficient Electric Light Sources

•Fluorescent (compact & linear)•Highly efficient low temperature long lasting source with a variety of color rendering properties.•Requires care when specifying•Components:

•Gas envelope (argon / krypton)•Electrified mercury vapor•phosphor coating•Ballast requirements

•Same letter and number code for shape and size

•Different types of bases/sockets get tedious so pay attention

•Fluorescent quality codes:•The magic “three digit number” on every lamp•Color temp. and CRI

Fluorescent lamp properties depend largely on the fluorescing phosphors coating the inside of the glass bulb

LIGHTING DESIGN LECTURE 6Efficient Electric Light Sources

•Linear fluorescent fixtures are a good way to get lots of diffuse light into a space

–High efficacy–Low heat–Long life–Even light distribution–Cheap–All shapes and sizes and looks–All require ballast (electronic NOT magnetic)–Dimmable, quiet, no flicker

•Simply require some thought when using–Downlights /area lights for diffuse area lighting–Shaded table and floor lamps–Utility spaces / closets–Linear under cabinet, millwork, display–Indirect applications (brackets, coves, slots)

•Basically, if you can hide the lamp, no one will notice

–Even vanity fixtures with the right CRI and CCT

Fluorescent sources with the right CRI and CCT can be used just like incandescent sources.

LIGHTING DESIGN LECTURE 6Efficient Electric Light Sources

•High Intensity Discharge•Very efficient , concentrated, high lumen output “directable” source

•Arc tube•Carbon electrodes / carbon arc•Electrified metal vapor•Ballast requirements•Re-strike time

•High intensity discharge create the same light textures as halogen sources, but are more efficient, lower CRI, difficult to dim technology

•High bay applications, street lighting, stadium flood•Accents: PAR lamps and reflector driven accent fixtures.

HID lamps create a small point of light similar to halogen sources. These “point sources” can be easily aimed and focused.

LIGHTING DESIGN LECTURE 6Efficient Electric Light Sources

•Light Emitting Diodes LED’s•Efficient, long life, tiny, controllable

•Diode wafer•Lens and reflector•RGB systems•Phosphor white

•LED’s are tiny sources that can pack a lot of light, different colors and different optics into one system

•Most commonly used for Color effects•White is a work in progress

The efficiency and color rendering capabilities of LED’s improve daily. Insist on seeing an LED product in action before specifying it.

LIGHTING DESIGN LECTURE 6 Efficient Electric Light Sources

Introduce In-Class Charrette•Reading Assignment:

•The Architecture of Light, Chapter 8, 16 and 30

•Midterm exam next week