Understanding Photometric Lighting

-Written by Ron Troyer

Even though 49% of all electrical consumption worldwide is dedicated to motors, one of the most life-altering, irreplaceable miracles of electricity is the ability to illuminate our world.  Imagine life without the convenience of flicking a switch to light our workplaces, homes, and lives. The importance of lighting can never be overstated.  According to the U.S. Energy Information Administration, residential sector electrical consumption for lighting (75 billion kWh) has dropped to 5% of total residential sector electricity consumption in 2019.  We can thank the advent of LED lighting for this minuscule fact.

Photometrics is the science of measuring visible light between the ultraviolet and infrared wavelengths on the human eye’s lighting spectrum (electromagnetic scale). In actuality, visible light to the human eye only occupies a very small percentage of the entire width of the electromagnetic spectrum, but within that narrow band exists everything that is important to us regarding lighting.

Table of Contents

• Three Types of Lighting
• Lighting Beam Angles
• General or Ambient Lighting
• Task Lighting
• Accent Lighting

Three Types of Lighting

We study this fascinating science in the better interest of enhancing our environment with light.  We break it down further with three distinct types of lighting that can be applied within any one room.  They are;

• General Lighting – recessed flood lighting and ceiling-mounted fixtures
• Task Lighting – recessed spotlighting, desk lamps, undercabinet lighting
• Accent Lighting – table lamps, wall sconces, bookshelf or art highlighting

Each of the three types of lighting is used functionally and artistically to create the all-important ambiance of a room.  The best lighting plans incorporate all three agendas in a workable combination of functions.  It is common for the lines between any two types of lighting to blur when serving double duty.  For example, recessed accent lighting of artwork on a wall or over a mantle often has some general lighting characteristics due to bounce-back or luminous light spillover.  It can be argued a stunningly beautiful chandelier can serve all three!

Lighting Beam Angles

To this end, lighting engineers use various lamps for general, task, and accent lighting, each with different beam angles depending on the objective.

• • Very Narrow Spot (VNSP) – 7 degrees or less
  • Narrow Spot  (NSP) – 8-15 degrees
  • Spot (SP) – 16-22 degrees
  • Narrow Flood (NFL) – 17-35 degrees
  • Flood (FL) – 36-45 degrees
  • Wide Flood (WFL) – 46-59 degrees
  • Very Wide Flood (VWFL) – 60-160 degrees and beyond

General or Ambient Lighting

The primary source of light in a room is the general light.  This allows for ingress and egress, as well as workstation illumination, and is often quite different from most mood lighting.  The 360-degree glow of a typical Edison lamp (A-19) is the workhorse of general lighting.  Any lamp with a wide beam of light up to 160 degrees makes good general room lighting (VWFL).  The switch that controls these lights is often not a dimmer (however, dimmers are mistakenly used for general lighting) and might stand alone or be the first in line when multiple switches are ‘ganged’ together to produce a row of three, four, or more switches/dimmers.

Task Lighting

When it comes to reading, cooking, sewing, writing, applying make-up, shaving, work benches and task lighting, a wide assortment of fixtures aid in this objective.  Floor lamps, table lamps, recessed lighting, drop lights, swing arm lamps, adjustable recessed lighting- these are all forms of task lighting.  Narrow floods and flood lamps serve these fixtures best.  Task lighting is often found to have its own dedicated switches or dimmers but can be ganged like all the others.

Accent Lighting

The job of beautifying our lives with the artistic use of lighting fixtures falls into the category of accent lighting.  When a piece of art, whether 3 dimensional or wall-mounted, requires specific illumination, accent lighting can be accomplished into a very poignant and dramatic statement with the interplay of dark, light, and shadow.  Track lighting was the 1970s and 80s version of moveable, adjustable accent lighting, which allowed the homeowners to create various scenes but served terribly as general room lighting.  Hiding or concealing the light source adds to the mystery of illumination and is one of the reasons why recessed lighting has become so popular when accentuation is needed.  Very Narrow, Narrow, and Spotlights dominate this category.  The switching (or dimming) order for these features is generally found in the middle or at the end or in a gang of switches.

Finding the right location on a wall for the controls is key in making general, accent and task lighting recognizable and useable.  In this respect, good enough is never good enough.  Some forethoughts about the switch/dimmer layout in a multi-gang of devices go a long way in helping the homeowner remember the order.  Exceed five devices in a gang and most of us struggle to recall which is general and which is task.

Years of compiled knowledge of general, task, and accent lighting trademarks of Lippolis Electric specialists are often offered free of charge by calling our main number at 914 738-3550 and requesting a quote.  Our best minds are on standby, waiting to hear from you.