7 Artificial Lighting
人工照明

The subject of this chapter is artificial lighting, and the following
chapter deals with natural lighting.

Although the principles of these two topics are treated
separately it is important that they are considered together
when designing a building.
The main functions of artificial lighting?

to provide enough light for people to
carry out a particular activity

to provide enough light for people to move about
with ease and safety
to display the features of the building in a manner
suitable for its character and purpose

To achieve these aims it is necessary to consider the
properties of lamps, of the lamp fittings 灯具and of the
room surfaces that surround them.
7.1 Lamps 灯

What is The oldest source of artificial light ?
the flame from fires, from candles and from oil lamps

Convert chemical combustion化学燃烧 to light energy

Modern sources of artificial light convert
electrical energy to light energy
(1) Incandescent sources白炽灯
produce
light by heating substances to a
temperature at which they glow发热and are
luminous.
(2) gas discharge sources气体放电灯
produce
light by passing an electric current through a gas or
vapour that has become ionised电离and hence able to conduct
electricity.
At
low pressure, a luminous arc or discharge is formed between
the electrodes and useful quantities of light are given off
7.1.1 how to evaluate the Properties of lamps
1) Luminous efficacy 光效 which is given by the
following formula.
Luminousflux output
luminousefficacy
Electricalpower input
Unit: lumens /watt (lm/W)
2) Life 寿命

The luminous efficacy of a lamp decreases with time and for a
discharge lamp it may fall by as much as 50% before the lamp
fails.

The nominal life of a lamp is usually determined by the
manufacturer by considering the failure rate of a particular
model of lamp combined with its fall in light output.

In a large installation it is desirable that all the lamps are
replaced at the same time on a specified maintenance schedule.
3) The correlated colour temperature (CCT) 相关色温
is the absolute temperature of a perfect radiator when the colour
apperance of the radiator best matches that of the light source
Unit : kelvin (K)
•色温反映灯光本身的表观颜色
•The CCT reflects the apparent color of light itself,
The
lower values of colour temperature indicate light
with a higher red content.

Some examples of colour temperatures are given below

Clear sky 晴天

Overcast sky 全阴天
5,000-8,000K

Tubular fluorescent lamps
3,000-6,500K

Tungsten filament lamps
12,000-24,000K
2,700-3,100K
Which one have the better color?
4）Colour rendering显色性is the ability of a light
source to reveal the colour appearance of
surfaces.

This ability is measured by comparing the
appearance of objects under the light source with
their appearance under reference source such as
daylight日光

One system specifies the colour rendering of
lamps by a colour rendering index（Ra) which has
a value of 100 for an ideal lamp. Practical sources
of white light range in Ra value between 50and 90
•显色性是指灯光对其照射的物体的影响作用。
To make a comparison of the colour rendering
qualities of light sources easier,
colour rendering groups have been defined:
The CIE colour rendering groups
Group
Ra
Importance
Typical application
1A
90...
accurate colour matching
100
Galleries画廊，美术馆, medical
examinations, colour mixing
1B
80...
accurate colour judgement
90
Home, hotels, offices, schools
2
60...
moderate colour rendering
80
Industry, offices, schools
3
40... accurate colour rendering is of
60
little importance
Industry, sports halls
4
20... accurate colour rendering is of no
40
importance
Traffic lighting

Some tasks such as colour matching in the printing
industry have high demands in accurate colour rendering
and require special attention from the lighting designer.

For normal offices, however, the colour rendering group
will be 1B or 2, which is easily achived with normal
fluoresent lamps.
Colour rendering index for different light sources
Light source
Colour rendering group
Incandescent
1A
Metal halide
1A ... 2
Fluorescent
1A ... 3
High pressure sodium
1B ... 4
Low pressure sodium
4
7.1.2 the fist type of artificial light
Incandescent lamps 白炽灯
Electric incandescent lamps work by passing an
electric current through a filament of metal and raising the
temperature to white heat.
When the metal is incandescent, at around 2800K , useful
quantities of light are given off.
1)
Most General Incandescent lamps is
tungsten filament lamp.
GLS lamps, or common light bulb, has a coiled filament
contained within a envelope of glass which may be clear or
frosted透明的或磨砂的.
The cost of a tungsten filament lamp is low and its
installation is simple ,
but the relatively short life of the lamp can cause the
labour costs of replacement to be high.

The low luminous efficacy of the lamp produces high
electrical running costs.

Only about 5% of the electrical energy is converted to
visible light and most of the energy consumed is given
off as heat, especially radiant heat.
2) The improved incandescent lamps:
Reflecting lamps 反射灯

The relatively large size of the standard tungsten filament lamp
makes it difficult to control the direction of the light.

Spot lamps 聚光灯 are filament lamps with the glass bulb
silvered inside and shaped to form a parabola 抛物线with the
filament at the focus.

This arrangement gives a directional beam of light which is
available in different widths of beam.

Sealed beam lamps密封光束灯 use similar techniques

Crown-silvered lamps 银冠灯 are standard filament
lamps where the glass bulb is silvered in front.

When this lamp is used with a special external reflector
it also gives narrow beams of light
some other improved incandescent lamp
3) Tungsten-halogen lamps卤钨灯

Tungsten –halogen lamps have filaments which run at
higher temperatures with the presence of a small
quantity of a halogen gas, such as iodine 碘 or bromine
溴.
4) Low-voltage system


uses 12volt lamps fed from the mains by a transformer.
low-voltage bulbs need a lower resistance ,so the
filament can be shorter, thicker and stronger.

The small size of these lamps give them good
directional qualities which make them popular in shops
for the display of goods.

The relatively low heat output of low-voltage systems
is also an important property in stores where high
levels of illumination can cause overheating.
7.1.3 the second type of artificial light
gas discharge sources
Most General gas discharge source is
Tubular fluorescent lamps 荧光灯管
Figure 7.2 Tubular fluorescent lamp
氩或氪
McMullan
A improved form is
Compact fluorescent lamps紧凑型荧光灯

Compact fluorescent lamps give a light quality suitable
for domestic purpose and the use of such lamps are
important technique for low-energy lighting in homes.

How is the coulur quality of gas discharge lamps?

Apart from the well-known tubular fluorescent lamp,
gas discharge lamps usually have a poor colour rendering

So they have in the past been restricted to outdoor lighting,
such as for roadways, where their generally poor colour
qualities have not been important.

Modern types of discharge lamp have a colour rendering
that is good enough for large-scale lighting inside
building such as factories and warehouses仓库.

Continuing technical advances are producing more
discharge lamps suitable for interior lighting

high efficiency of such lamps can give significant
savings in the energy use of buildings.
Some Modern types of discharge lamps
Mercury discharge lamps 汞放电灯

An uncorrected mercury lamp emits sharp light at certain blue
and green wavelengths.
In
the mercury halide lamp
卤汞灯, metallic halides are
added to the basic gas
discharge in order to
produce better colour
rendering and to raise the
efficacy
A metal halide gas discharge lighting
system provides illumination for a
college baseball game at Olsen Field
in College Station, Texas. Note the
various colors of the lights as they
warm up
Example of a Metal Halide lighting pole, at a
baseball field
Sodium discharge lamps钠放电灯

Low-pressure sodium
lamps produce a distinctive
鲜明的yellow light that is
virtually 实质上
monochromatic and gives
poor colour rendering .

however the efficacy of the
lamp is very high and they
have been traditionally
used for street lighting
A low pressure sodium/sodium oxide
(LPS/SOX) streetlamp at full power
Office building illuminated by high pressure sodium lamps.

High-pressure sodium lamps （SON） produce a
continuous spectrum without much blue light but with a
colour rendering that is more acceptable than the lowpressure sodium lamp.

SON lamps are used in modern street lighting and for
the economic lighting of large areas such as forecourts篮
球场 and warehouses仓库.
7.1.5 Lamp and energy conservation

Lighting is an important area of energy conservation in
buildings as new systems can be installed in existing
buildings as well as in new buildings.

The energy saved by a modernised lighting system usually
pays for the cost of the installation within a few years, which
is a shorter payback period than most methods of saving
energy in buildings.

The major lamp companies of the World are therefore
developing new types of low-energy lamps including
improvements to the compact fluorescent lamp and high
pressure discharge lamps described above.
7.2 Luminaires
灯具
LOR  DLOR  ULOR
downwards light output of luminaire
DLOR 
light output of its lamp(s)
upwards light output of luminaire
ULOR 
light output of its lamp(s)
T otallight output of luminaire
LOR 
light output of its lamp(s)
Let’s do some judgements
Direct 直接向下型
General diffusing 普通漫反射型
Semi-indirect
半间接型
40
7.3 how to do Lighting design 照明设计
First , find the standard service illuminance levels that are
recommended for a variety of interiors and tasks given in Table
7.3.
P156
The aim of Lighting design is to reach the illuminance levels
Then , use Lumen method 流明法 to calculate the number of
lamps needed.
EA
N
F  UF  LLF
EA
N
F  UF  LLF
UF= utilisation factor 使用系数 is the ratio of the total flux
reaching the working plane compared to the total flux output
of the lamps table 7.4
P158
DLOR
L W
RI 
H m  (L  W)
房间指数
Hm——mounted height of the luminaire above the working plane
LLF=light loss factor 光损失系数is the ratio of the illuminance
provided at some given time compared to the initial illuminance
At the end of design, we should place these lamps in a
regular grid pattern and
their spacing must not exceed certain distances.
This maximum spacing depends on the type of luminaire and the
height at which they set. Typical values are as follows
For fluorescent tubes in diffusing luminiaires
Smax=1.5XHm
For filament lamps in direct luminaires
Smax=1.0XHm
Figure 7.6 spacing of luminaires P160
Worked example 7.1
A factory space measuring 40m by 12m by 4m in height
requires a service illuminance of 500lux on the work benches
which are set 1m above the floor. The 65W tubular fluorescent
lamps chosen have a luminous efficacy of 80lm/W. they are to
be mounted on the ceiling in luminaires which have a DLOR of
50%. The room reflectances are 0.5 for the ceiling and 0.3 for
the wall; the initial light loss factor is 0.7
a) Use the lumen method of design to calculate the number of
lamps required
b) Suggest a suitable layout for the lamp fittings.





E=?
A=?
F=?
UF=?
LLF=?
EA
N
F  UF  LLF
So number of lamps required=144 lamps
Suggested layout: 9 rows行of 16 luminaires
Check spacing using Smax=1.5XHm
=1.5X3=4.5m
So the suggested layout is satisfactory provided that the
distance between lamps is not greater than 4.5m
In a particular lighting system design ,the
following factors need to be considered

Light quantity should reach the illuminance levels
Natural light 自然光
Colour
quality 光的颜色
48
Glare 眩光




Directional quality 方向性
Energy use 能耗
Costs 运行费
Physical properties 物理性能
That’s all for chapter 7, let’s do a summary together.
chapter 7 Artificial Lighting
7.1 Lamps 灯
7.1.1 how to evaluate the Properties of lamps
Luminous efficacy 光效
Life 寿命
The correlated colour temperature (CCT) 相对色温
Colour rendering显色性
7.1.2 Incandescent lamps 白炽灯
GLS lamps, or common light bulb
Reflecting lamps 反射灯
Spot lamps
Sealed beam lamps
Tungsten-halogen lamps卤钨灯
low-voltage bulbs
Crown-silvered lamps
7.1.3 Discharge lamps放电灯
Fluorescent lamps 荧光灯
Compact fluorescent lamps紧凑型荧光灯
Mercury discharge lamps 汞放电灯
Sodium discharge lamps钠放电灯
7.2 Luminaires 灯具
7.3 how to do Lighting design 照明设计
First , find the
standard service illuminance levels
Then , use Lumen method 流明法 to calculate the
number of lamps needed.
EA
N
F  UF  LLF
At the end of design, we place these lamps in a
regular grid pattern
Practices in class
1 Modern sources of artificial light convert (
A chemical energy
B electrical energy
C light energy
D heat energy
) to (
)
2 Oldest sources of artificial light convert (
A chemical energy
B electrical energy
C light energy
D heat energy
) to (
)
3 Modern sources of artificial light are of
two general types:(
)
A incandescent lamps
B discharge lamps
C mercury discharge lamps
B tungsten filament lamps
4 The following lamp is （
A common light bulb
B spotlamp
C crown-silvered lamp
D tungsten-halogen lamp
）
5 The following lamp is （
）
A tubular fluorescent lamp
B compact fluorescent lamp
C mercury discharge lamp
D sodium discharge lamp