Review and Extra Resources

EGEE 102 Lesson 6 Review

For task lighting a specific task, specific task meaning either reading or writing or cooking or repairing something, that requires generally about 40 to 50 foot candles. Sometimes, if you're working on small objects, you may need even a little more light. Accent lighting is the lighting that is used to highlight certain things at home, for example, a painting or a statue or something you want to highlight.

And you should be able to design lighting for certain areas. That's something that you may want to look at. Let's say you're designing for a general purpose hallway. You have 10 square feet, and each square foot requires about 10 lumens, which means 100 square feet requires 1,000 lumens. So you should be able to figure that out.

Color rendering index - different lighting produces different abilities to look at true colors. And you need to know the color rendering index. It is measured on a scale from zero to 100, and 100 being perfect colors or absolutely no color shift. And that is generally possible in natural light.

And when you have a room, how many lamps are required? That depends on how many lumens. You need total area and lumens, and each bulb gives out a certain number of lumens, and how many bulbs you require is based on that.

For example, if you have a room of 100 square feet, you need, let's say, 20 foot candles, which means 20 lumens per square foot. So every square foot requires 20 lumens. So in this case, 20 times 100 would be 2,000 lumens needed for that room.

And let's say if a 60-watt bulb gives you 1,000 lumens, you need two of these bulbs to get that 2,000 lumens. Of course, there are other factors like reflections off the walls and also the light fixture efficiency and so on and so forth. So you need to know the factors that affect, particularly the number of lamps required.

Types of lighting - you need to know the differences between incandescence, fluorescence, and high-intensity discharge lamps - how you produce the light, the process, and the hardware that is involved. And you should be able to perform life-cycle analysis. In other words, if you have two different types of light, for example an incandescent light and a CFL bulb - you are able to perform a life-cycle analysis using these two bulbs.

Life cycle analysis is cost to own and operate for the entire lifetime of the bulb. And remember, you have to compare for the same life period. These are not different lifetimes. If one bulb lasts 1,000 hours, and the other one last 8,000 hours, you have to use eight of these 1,000-hour bulbs to compare, actually. And cost to own, cost to supply the energy, energy cost, and maintenance costs together will be the lifetime cost.