AREN 320 Test #2 Terms

Foot Candle Definition

the illuminance on a square foot surface from a uniform light source or the amount of light that hits a 1 Sqft surface when 1 lumen is shined from 1ft away

1 footcandle = _____ lux

10.764 lux

What is the foot candle formula?

Candle Power / distance^2

Candle Power

The luminous intensity of a light source, expressed in candelas.

.981 Candela often 1:1 with the # of candelas

Lumens (Definition)

or brightness, the measure of the total amount of Visible light to the human eye

Illuminance Definition

Amount of light falling on, illuminating a given surface per unit area (lux or foot-cand)

Illuminance is measured in:

1 lux = 1 lm/m2 or 1 lm/ft^2

Luminance Definition:

-the intensity of light reflected from an illuminated surface.

-candelas per square meter, 1 ft lambert = 3.426 cd/m2, 1 nit = 1 Cd/m2

Coefficient of utilization (CU)

the percentage of lamp lumen emitted by a luminaire that ultimately reaches a task surface.

Lighting data sheet shows:

-plotted candela values

-diagrams of the spread of light and intensity

Perfect W/C/F reflective values:

Ceiling = 80%

Wall = 50%

Floor = 20%

Lumen Method, Zonal Cavity Method is better for

Comparing different lights

What are the factors affecting light?

-CU - Coe of Utilization

-LLF - Lighting Loss Factor

-MF - Maintenance Factors

Factors affecting CU

-Luminaire Distance of lamp lumens

-Room Size

-Reflective Values

Lighting Loss Factors

Lamp Lumen Depreciation, Dirt Depreciation, Environmental Depreciation, Ballast Factors

Maintenance Factors

Recoverable

Nonrecoverable

Recoverable Maintenance Factors

Lamp Burnouts (80%)

Lamp Lumen Depreciation (70%)

Dirt Depreciation:

-Indirect Lighting (65%)

-Industrial Environmental(50%)

-Open Fixtures(85%)

Non-recoverable maintenance factors

Ballast Factor (90%)

Ambient Light Fixture

Supply Voltage Variation 4%

Exit Signage: whats required?

- Exit signage shall be internally lit

- Exit signs shall be connected to emergency power

and illuminated for not less than 90 minutes during

normal power loss

- Labeled/Listed in accordance w/UL 924

What is an individual battery unit?

Battery pack is provided for each light sign

Advantages and Disadvantages of Individual Battery Units

Advantages

-Simple

-Cheap

Disadvantages

-Many Units

-Testing

-Maintenance

Central Lighting Interior has how many pieces of equipment?

One

Advantages and Disadvantages of Central Lighting Interior

Advantages

-Less Maintenance

-Monitoring

-Low Arch Impact

Disadvantages

-Single Point Failure

-More Expensive

Types of inspection and testing:

Daily: Central Battery Cabinets

Monthly: Short Duration Test

Annually: Full Duration Test(3hrs)

Article 700.12(F)

- Supply circuit to the unit has to

be connected to the same circuit as

the normal lighting

- Allows emergency lighting to function

in the branch circuit

- Emergency lighting Load must be

auto energized within 10 Seconds of

outage, & most be on for at

least 90min or for the time it takes

to evacuate

Outdoor Lighting Problem Areas

Lighting Pollution

Light Trespass

Light Pollution (definition)

The inappropriate or excessive use of artificial light

Glare (definition)

Excessive Brightness

Skyglow (definition)

brightening of the night sky over inhabited areas

Light Trespass (definition)

Light falling where it is not intended or needed

Light Clutter (definition)

Bright and confusing groupings of lights

BUG Rating System

"Backlight, Upplight, and glare"

Based on internal/external lighting design

Design Guide:

Guidelines for security for people, poverty, public spaces

MEEB Tbl 16.4

IESNA(G-1; Section 4) Advanced Lighting for Security Reasons

ASHRAE 90.1

Outdoor Lighting Should:

-Only be on when needed

-only light the area needed

-no brighter than necessary

-be fully shielded downward

Outdoor Lamp Types

Low Pressure Sodium(LPS)

High Pressure Sodium(HPS - Most common

Metal Halide (white light)

LED

What are 7 Daylighting factors?

-Latitude

-Time of Day

-Time of Year

-Weather

-Exterior Factors

-Attributes of the building

Energy 101 =

Daylighting

When is the equinox?

March 21st and September 21st

When are the solstices?

June 21 and December 21

Altitude:

the angle its position forms above the horizon

Azimuth

the number of degrees east or west

Parts of Daylighting

-Sunlight

-Sky Lighting

-Reflected Light

Criteria for amount/location daylighting

-View

-Health

-Illuminance

-Productivity

-Sustainability

Fenestration Definition

Arrangement of daylight openings

-windows, skylights, roofs monitors

Foot Candle Amount for Clear Sky and Overcast Sky

Clear = 7k-10k FC

Overcast = 1k-5k FC

Holistic Approach

Max impact of daylighting(Deep into Space)

-Site

-Architecture

-Interiors

-Lighting

Daylight factor (DF) is best defined as:

the ratio of daylight intensity between an interior point and an exterior reference point

Reactive Approach

Attempting to "fix" afterword

Daylight Factor Ratios:

DF under 2 = Not well lit/needs artificial lighting

DF BTW 2-5 = Adequately lit/may need artif lights

DF over 5 = Well lit/ No artif light

Reflectance is what:

the most important contribution to lighting system efficiency

General Rule for Uniformity:

into a room is 1.5-2 * height of window

-Consider primary/secondary zones require photocell dimming control

Managing Daylight

The east west elongation works well with northern climates

-Southern exposures are more easily controlled

-Holistic approach balances daylight, electric light, and energy

Window Placement

"Daylighting" - Placed @ or above 7.5 feet

50-70% Transmittance

"Viewing Placed at 7.5 feet or less

40% transmittance

Shading Devices

-Fixed

Horizontal/Vertical

-Active

Auto/Daily/Seasonal

-Manual

What does direct lighting look like?

Direct

What does semi direct lighting look like?

Semi direct

What does general diffuse lighting look like?

General Diffuse

What does direct indirect lighting look like?

Direct indirect

What does semi indirect lighting look like?

Semi indirect

What does indirect lighting look like?

Indirect