Lamp Running Costs

Light Output Comparison Chart

Lumen
GLS
Hal
Mbf
Son
M/Hal
Sox
Output
           
50,000
49,000
48,000
47,000
400
£128
46,000
45,000
44,000
43,000
42,000
41,000
40,000
39,000
38,000
400
£128
37,000
36,000
35,000
34,000
33,000
1500
£480
32,000
31,000
30,000
29,000
28,000
27,000
250
£80
26,000
25,000
24,000
23,000
22,000
1000
£320
400
£128
21,000
250
£80
20,000
19,000
17,000
16,000
15,000
750
£240
150
£48
14,000
13,000
250
£80
150
£48
12,000
11,000
10,000
9,500
9,000
500
£160
8,000
7,600
55
£17
7,000
6,500
6,300
125
£40
6,000
5,800
70
£22
70
£22
5,000
4,800
300
£96
4,500
35
£11
4,000
3,800
80
£25
3,300
50
£16
3,100
200
£64
2,500
2,100
150
£48
50
£16
18
£6
1,800
1,200
1,000
100
£32
500
Lumens
GLS
Hal
Mbf
Son
M/Hal
Sox

Based on annual running costs for 4,000 hours (@8p per kW /h)

Factors not included:

Lamp cost:
Lamp life:

GLS - 1000 hrs
HAL -Halogen - 2000 hrs
M/Hal - Metal Halide - 6,000 hrs
Mbf - Mercury - 16,000 hrs
Son - Sodium - 24,000 hrs
Sox - 16,000
Maintenance and lamp replacements
Cost of Fitting
:.Starting time requirement

Colour Rendering

Lamp
Colour Temp. (K)
Colours enhanced
Colours subdued
.
SON
2100
yellow orange
blue green red
yellow
functional
GLS
2700
orange red
blue green
"cosy" warm
HAL
2900
orange red
blue green
"crisp" warm
MBF
4000
blue green
yellow red
neutral
white
M/HAL
5000
blue green
.
fresh
active
.
5000 +
.
.
daylight

Lamp Types

Halogen Lamp

A short name for the tungsten-halogen lamp. Halogen lamps are high pressure incandescent lamps containing halogen gases such as iodine o bromine which allow the filaments to be operated at higher temperature and higher efficacies. A high-temperature chemical reaction involvin tungsten and the halogen gas recycles evaporated particles of tungste back onto the filament surface.

High-Intensity Discharge (HID) Lamp

A general term for mercury, metal halide and high-pressure sodium lamps. HID lamps contain compact arc tubes which enclose various gases and metal salts operating at relatively high pressures and temperatures.

High-Pressure Sodium (HPS) Lamp

HPS lamps are high intensity discharge light sources which produce light by an electrical discharge through sodium vapor operating at relatively high pressures and temperatures.

Incandescent Lamp GLS

A light source which generates light utilizing a thin filament wire (usually of tungsten) heated to white heat by an electric current passing through it.

Mercury Lamp

A high-intensity discharge light source operating at a relatively high pressure (about 1 atmosphere) and temperature in which most of the light is produced by radiation from excited mercury vapor. Phosphor coatings on some lamp types add additional light and improve colour rendering.

Metal Halide Lamp

A high-intensity discharge light source in which the light is produced by the radiation from mercury, plus halides of metals such as sodium, scandium, indium and dysprosium. Some lamp types may also utilize phosphor coatings.

Other Terms

Average Rated Life

The median time it takes for a lamp to burn out. For example, a 60-watt Soft White bulb can be expected, on the average, to burn for 1,000 hours. Based upon continuous testing of lamps in laboratories, the 1,000 hour rating is the point in time when 50% of the test samples have burned out and 50% are still burning.

Lumen

The international (SI) unit of luminous flux or quantity of light. For example, a candle provides about 12 lumens. A 60-watt Soft White incandescent lamp provides 840 lumens.

Lumens Per Watt (lpW)

A measure of the efficiency, or, more properly, “efficacy” of a light source. Efficacy is easily calculated by taking the lumen output of a lamp and dividing by the lamp watts. For example, a 100-watt lamp producing 1750 lumens has an efficacy of 17.5 lumens per watt.

Typical lamp efficacies:

Edison’s first lamp 1.4 lpw
Incandescent lamps 10- 40
Halogen incandescent lamps 20- 45
Fluorescent lamps 35- 100
Mercury lamps 50- 60
Metal-halide lamps 80- 115
High-pressure sodium lamps 100- 140

Note: the values above for discharge lamps do not include the effect of the ballasts which must be used with those lamps. Taking ballast losses into account reduces “system” or lamp-ballast efficacies - typically by 10-20 percent depending upon the type of ballast used.