Chapter 15: Lighting

Question 1

What is a lumen?

Answer 1

Amount of light emitted (brightness output)

Question 2

What is a footcandle?

Answer 2

Light level on a surface (lumens per square foot)

Question 3

Difference between lumens and footcandles

Answer 3

Lumens = source output
Footcandles = light received at surface

Question 4

What is CRI (Color Rendering Index)?

Answer 4

Accuracy of color appearance under a light source

Question 5

Why are LEDs widely used in interiors?

Answer 5

High efficiency, long life, low heat

Question 6

When is high CRI lighting critical?

Answer 6

Retail, healthcare, art display, makeup

Question 7

What color temperature is typically used for residential spaces?

Answer 7

Warm light (~2700–3000K)

Question 8

What color temperature is common for offices?

Answer 8

Neutral (~3500–4100K)

Question 9

What is direct lighting?

Answer 9

Light aimed downward to task surface

Question 10

What is indirect lighting?

Answer 10

Light reflected off ceiling or walls

Question 11

What is diffuse lighting?

Answer 11

Even light in all directions

Question 12

What lighting reduces glare the most?

Answer 12

Indirect lighting

Question 13

What lighting produces the strongest shadows?

Answer 13

Direct lighting

Question 14

What causes glare?

Answer 14

Excessive brightness contrast

Question 15

What is veiling reflection?

Answer 15

Reflected light reducing visibility of task

Question 16

How do you reduce glare at computer workstations?

Answer 16

Indirect lighting or reposition fixtures parallel to screens

Question 17

What is ambient lighting?

Answer 17

Overall illumination

Question 18

What is zoning in lighting?

Answer 18

Separate control of fixture groups

Question 19

What does a lighting plan show?

Answer 19

Fixture type, location, switching, and mounting

Question 20

Office glare complaint → best fix?

Answer 20

Indirect or repositioned lighting

Question 21

Retail product looks dull → best fix?

Answer 21

Higher CRI lighting

Question 22

Energy reduction goal → best strategy?

Answer 22

Daylight + occupancy sensors

Question 23

Conference room video presentations → best lighting?

Answer 23

Dimmable layered lighting

Question 24

Purpose of emergency lighting?

Answer 24

Provide illumination during power failure

Question 25

What must emergency lighting illuminate?

Answer 25

Egress paths

Question 26

If you double the distance from a light source, what happens to light level?

Answer 26

Drops to one-quarter (inverse square law)

Question 27

Why does mounting height affect brightness on a surface?

Answer 27

Light spreads out as distance increases

Question 28

Why do darker finishes require more lighting than lighter finishes?

Answer 28

They reflect less light (lower reflectance)

Question 29

Which surface reflects the most light?

Answer 29

Light matte surfaces

Question 30

What is beam spread?

Answer 30

Angle light leaves a fixture

Question 31

Narrow beam is used for what?

Answer 31

Accent lighting / highlighting objects

Question 32

What is a wall wash?

Answer 32

Even wall surface illumination

Question 33

Wide beam is used for what?

Answer 33

General illumination

Question 34

What is wall grazing?

Answer 34

Light close to surface to emphasize texture

Question 35

Which shows texture more — grazing or washing?

Answer 35

Grazing

Question 36

Why place workstations perpendicular to windows?

Answer 36

Reduce glare on screens

Question 37

Why are skylights often diffused?

Answer 37

Prevent harsh contrast and glare

Question 38

What causes contrast glare near windows?

Answer 38

Bright window + dark interior surfaces

Question 39

What is a troffer?

Answer 39

Rectangular recessed ceiling fixture (typical office)

Question 40

Why is uniform lighting sometimes undesirable?

Answer 40

Reduces visual hierarchy and orientation

Question 41

Why should lights near windows be separately switched?

Answer 41

Daylight control zones

Question 42

What control improves user satisfaction in offices?

Answer 42

Local/manual control

Question 43

What activates emergency lighting?

Answer 43

Power failure

Question 44

Why does glossy flooring increase glare?

Answer 44

Specular reflection

Question 45

Why does textured wall need grazing light?

Answer 45

Creates shadow contrast

Question 46

What is lamp life rated in?

Answer 46

Hours of operation

Question 47

What does lumen depreciation mean?

Answer 47

Light output decreases over time

Question 48

What is maintained illuminance?

Answer 48

Light level after aging and dirt are considered

Question 49

What reduces light output besides distance?

Answer 49

Dirt, aging lamps, surface absorption

Question 50

Why is maintained illuminance important?

Answer 50

Designers plan for future dimming, not just new lamps

Question 51

Why are higher initial footcandles often specified?

Answer 51

Light output decreases over time

Question 52

What is lighting uniformity?

Answer 52

Even distribution of light across a surface

Question 53

Why is some contrast desirable?

Answer 53

Helps orientation and visual interest

Question 54

When is high lighting uniformity critical?

Answer 54

Task-heavy environments (offices, healthcare)

Question 55

Why is CRI critical in healthcare and retail?

Answer 55

Accurate color judgment (skin tone/products)

Question 56

What happens when color temperature is too warm in offices?

Answer 56

Reduced alertness and visual clarity

Question 57

What is modeling in lighting?

Answer 57

Light/shadow balance revealing shape and depth

Question 58

Why is completely shadowless lighting undesirable?

Answer 58

Objects appear flat

Question 59

Why avoid strong glare at signage?

Answer 59

Reduces legibility

Question 60

Why is emergency lighting separate from normal circuits?

Answer 60

Must function during power failure

Question 61

What power source often supports emergency lighting?

Answer 61

Battery or generator backup

Question 62

What types of rooms in a large office benefit most from daylight sensors?

Answer 62

Rooms with access to natural daylight, such as perimeter offices, conference rooms with windows, open office areas near exterior walls, and lobbies with large windows.

Question 63

The ETL mark indicates that a product has been tested and certified for safety by __________. Products include appliances – household and commercial; residential and commercial lighting – lamps, components, controls, and luminaires; and furniture – performance, electrical safety, and flammability.

Answer 63

Intertek