Lighting Flashcards Preview

Building codes require a minimum of 1 fc at the floor level of areas that serve as means of egress. For assembly occupancies, such as an auditorium or theater, the level may reduced to 0.2 fc during performances, but must be automatically restored to 1 fc upon activation of the buildings fire alarm system. Exceptions to the minimum include U, guest rooms in group R-1, dwelling rooms, and sleeping rooms in Groupds R-2 and R-3 occupancies. Sleeping rooms in Group 1 occ are also exempt.

A=quiet; F=noisy

a. Globe Valve

Light sources that can be seen on a surface. They involve task and light source.

Illuminannce = E (In); Luminance = L (Leaving) Illuminance measured in fc Luminance measured in footlambert

Cp are alanogous to voltage (electrical) or pressure (hydraulic)

Lumens are analogous to amperes (electrical) or flow (hydraulic)

Lumens are a measure of photometric power, meaning it is perceived by the human eye as a function of physiology

Illuminating Engineering Society of North America

Measured how closely the perceived colors of an object illuminated with daylight of the same color temp. Max CRI is 100 so a rating of 85 is good

2.3 W/sq ft

Up to 150 lm/W, produces yellow light, used for street lighting

80 – 140 lm/W, uses Hot sodium Vapor

1. low cost 2. instant start and restart 3. simple, inexpensive dimming 4. simple, compact installation 5. cheap fixtures 6. focusability as a point sorce 7. high power factor 8. lamp life independent of number of starts 9. skin flattering, full spectrum color

1. low efficacy 2. short lamp life 3. critical voltage sensitivity

1. where use is infrequent 2. where there is frequent short duration use 3. where low cost dimming is required 4. where minimum initial cost is required 5. where good color rendering is required

R, BR, ER, PAR

accurate beam control narrow=spot wide=flood

C. tinted glass Although tintied glass would reduce the heat load, it would not be good for maximizing daylighting. Low e glass or super windows with clear glazing would be more appropriate. All other choices would be good ways to minimize direct sunlight on the glass while improving transmitted light to the interior of the building

B. azimuth

The angle of the north south axis of the earth relative to the sun. It's what causes seasons to happen throughout the year.

Type,wattage,diameter,color,method of starting

The ratio of luminous flux emitted to the toal power input tot eh source; measured in lumens per watt

luminance

Luminance is the luminous flux per unit of projected area and unit solid angle leaving a surface, either reflected or transmitted.

 the reflectance and transmittance properties of materials and the directions from which they are viewed. 

It's calculated by multiplying the reflectance of material times the illluminance. 

indandescents 

An incandescent has a high color rendering index (CRI) and a low color temperature, with a predominance of light in the red range. 

A cool white flourescent lamp has more blue and green light and its spectral distribution makes skin tones appear more gray and washed out. oth mercury vapor and metal halide lamps have poor color rendering indexes and are not appropriate for lighting areas where skin tone rendition is important. 

B. dirt accumulation

D. lumens per lamp

E. room size

F. wall reflectance

THe zonal cavity method is used to calculate the total number of luminaires required to achieve the desired average illumination on the work surface, which is asusmed to be 30 in above the floor. The variables considered in the calculation include the level of illumination desired, the area of the room, the number of lamps in wach luminaire, the lumen output of each lamp, the coefficient of utilization, the light loss factor (LLF) wall reflectance, and the gradual loss of light due to dirt accumulation. 

It's used to calculate the total number of luminaires required to achieve the desired averageillumination on the work surface, which is assumed to be 30 inches AFF. 

-level of illumination desired

-the area of the room

-the number of lamps in each luminaire

-the lumen output of each lamp

-the coefficient of utilization

-light loss factor

-wall reflectance

-and teh gradual loss of light due to dirt