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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 pro
perties of lamps, of the lamp fittings 灯具 and of the roo
m surfaces that surround them.
7.1 Lamps 7.1 Lamps 灯灯
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
produce light by heating substances to a t
emperature at which they glow 发热 and are
luminous.
(1) Incandescent sources(1) Incandescent sources 白炽灯白炽灯
(2) gas discharge sources(2) gas discharge sources 气体放电灯气体放电灯
produce light by passing an electric current through a gas or va
pour that has become ionised 电离 and hence able to conduct el
ectricity.
At low pressure, a luminous arc or discharge is formed betwee
n the electrodes and useful quantities of light are given off
7.1.1 how to evaluate the Properties of lamps7.1.1 how to evaluate the Properties of lamps
1) Luminous efficacy 1) Luminous efficacy 光效光效 which is given by the following formula.
inputpower Electrical
outputflux Luminousefficacy luminous
Unit: lumens /watt (lm/W)
2) Life 2) Life 寿命寿命
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) 3) The correlated colour temperature (CCT) 相关色温相关色温 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 Clear sky 晴天 晴天 12,000-24,000K12,000-24,000K
Overcast sky Overcast sky 全阴天 全阴天 5,000-8,000K5,000-8,000K
Tubular fluorescent lamps 3,000-6,500KTubular fluorescent lamps 3,000-6,500K
Tungsten filament lamps 2,700-3,100KTungsten filament lamps 2,700-3,100K
Which one have the better color?Which one have the better color?
44 )) Colour renderingColour rendering 显色性显色性 is the ability of a light
source to reveal the colour appearance of surface
s.
This ability is measured by comparing the appeara
nce of objects under the light source with their app
earance under reference source such as daylight
日光日光 One system specifies the colour rendering of lamp
s by a colour rendering index ( Ra) which has a v
alue 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...100
accurate colour matching Galleries 画廊,美术馆 , medical examinations, colour mixing
1B 80...90
accurate colour judgement Home, hotels, offices, schools
2 60...80
moderate colour rendering Industry, offices, schools
3 40...60
accurate colour rendering is of little importance
Industry, sports halls
4 20...40
accurate colour rendering is of no importance
Traffic lighting
Some tasks such as colour matching in the printing indus
try 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 fluore
sent 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 7.1.2 the fist type of artificial light Incandescent lamps Incandescent lamps 白炽灯白炽灯
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)1) Most General Incandescent lamps isMost General Incandescent lamps istungsten filament lamp.tungsten filament lamp.
GLS lamps, or common light bulb, has a coiled filament contain
ed 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 install
ation is simple ,
but the relatively short life of the lamp can cause the labo
ur costs of replacement to be high.
The low luminous efficacy of the lamp produces high ele
ctrical running costs.
Only about 5% of the electrical energy is converted to vis
ible light and most of the energy consumed is given off a
s heat, especially radiant heat.
2) 2) The improved incandescent lamps: ReflThe improved incandescent lamps: Reflecting lamps ecting lamps 反射灯反射灯
The relatively large size of the standard tungsten filament lamp
makes it difficult to control the direction of the light.
Spot lamps 聚光灯聚光灯 are filament lamps with the glass bulb silver
ed inside and shaped to form a parabola 抛物线抛物线 with the filam
ent at the focus.
This arrangement gives a directional beam of light which is avail
able in different widths of beam.
Sealed beam lamps 密封光束灯密封光束灯 use similar techniques
Crown-silvered lamps 银冠灯银冠灯 are standard filament lam
ps where the glass bulb is silvered in front.
When this lamp is used with a special external reflector i
t also gives narrow beams of light
some other improved incandescent lampsome other improved incandescent lamp
3) Tungsten-halogen lamps 3) Tungsten-halogen lamps 卤钨卤钨灯灯
Tungsten –halogen lamps have filaments which run at hi
gher temperatures with the presence of a small quantity
of a halogen gas, such as iodine 碘 or bromine 溴 .
4) Low-voltage system4) 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 7.1.3 the second type of artificial lightthe second type of artificial light gas discharge sourcesgas discharge sources
Most General gas discharge source isMost General gas discharge source is
Tubular fluorescent lamps Tubular fluorescent lamps 荧光灯管荧光灯管
Figure 7.2 Tubular fluorescent lamp
McMullan
氩或氪
A improved form is A improved form is
Compact fluorescent lampsCompact fluorescent lamps 紧凑型荧光灯紧凑型荧光灯
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 imp
ortant.
Modern types of discharge lamp have a colour rendering
that is good enough for large-scale lighting inside buildin
g such as factories and warehouses 仓库 .
Continuing technical advances are producing more disch
arge lamps suitable for interior lighting
high efficiency of such lamps can give significant saving
s in the energy use of buildings.
Mercury discharge lamps Mercury discharge lamps 汞放电灯汞放电灯 An uncorrected mercury lamp emits sharp light at certain blue
and green wavelengths.
Some Modern types of discharge lampsSome Modern types of discharge lamps
In the mercury halide lamp
卤汞灯 , metallic halides are
added to the basic gas disc
harge in order to produce be
tter colour rendering and to r
aise 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 lampsSodium discharge lamps 钠放电灯钠放电灯
Low-pressure sodium lamp
s produce a distinctive 鲜明的 yellow light that is virtu
ally 实质上 monochromatic
and gives poor colour rend
ering .
however the efficacy of the
lamp is very high and they
have been traditionally use
d 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 conti
nuous spectrum without much blue light but with a colour
rendering that is more acceptable than the low-pressure
sodium lamp.
SON lamps are used in modern street lighting and for th
e economic lighting of large areas such as forecourts 篮球场 and warehouses 仓库 .
7.1.5 Lamp and 7.1.5 Lamp and energy conservationenergy 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 short
er payback period than most methods of saving energy in buildi
ngs.
The major lamp companies of the World are therefore developin
g new types of low-energy lamps including improvements to the
compact fluorescent lamp and high pressure discharge lamps d
escribed above.
7.2 Luminaires7.2 Luminaires灯具灯具
lamp(s) its ofoutput light
luminaire ofoutput light downwardsDLOR
lamp(s) its ofoutput light
luminaire ofoutput light upwardsULOR
lamp(s) its ofoutput light
luminaire ofoutput light TotalLOR
ULORDLOR LOR
Let’s do some judgements
Direct 直接向下型
40
General diffusing 普通漫反射型
Semi-indirect
半间接型
7.3 how to do Lighting design 7.3 how to do Lighting design 照明设计照明设计
First , find the standard service illuminance levels that are rec
ommended 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 l
amps needed.
LLFUFF
AEN
DLOR
)WL(H
WLRI
m
房间指数房间指数
Hm——mounted height of the luminaire above the working plane
LLFUFF
AEN
UF= utilisation factor 使用系数使用系数 is the ratio of the total flux r
eaching the working plane compared to the total flux output
of the lamps table 7.4 P158table 7.4 P158
LLF=light loss factor 光损失系数光损失系数 is the ratio of the illuminance p
rovided 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 distancestheir 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 luminiairesFor fluorescent tubes in diffusing luminiaires
Smax=1.5XHm
For filament lamps in direct luminairesFor filament lamps in direct luminaires
Smax=1.0XHm
Figure 7.6 spacing of luminaires P160
Worked example 7.1Worked example 7.1
A factory space measuring 40m by 12m by 4mmeasuring 40m by 12m by 4m in height requ
ires a service illuminance of 500lux on the work benches whic
h are set 1m above the floor. The 65W tubular fluorescent lam
ps 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 la
mps required
b) Suggest a suitable layout for the lamp fittings.
E=? A=? F=? UF=? LLF=?
LLFUFF
AEN
So number of lamps required=144 lamps
Suggested layout: 9 rows9 rows 行行 of 16 luminairesof 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 In a particular lighting system design ,the following factors need to be consideredfollowing factors need to be considered
Light quantity should reach the illuminance levels
Natural light 自然光
48
Colour quality 光的颜色
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 7.1 Lamps 灯灯7.1.1 how to evaluate the Properties of lamps7.1.1 how to evaluate the Properties of lamps
Luminous efficacy Luminous efficacy 光效光效
Life Life 寿命寿命
The correlated colour temperature (CCT) The correlated colour temperature (CCT) 相对色温相对色温
Colour renderingColour rendering 显色性显色性
7.1.2 Incandescent lamps 7.1.2 Incandescent lamps 白炽灯白炽灯
GLS lamps, or common light bulb
Reflecting lamps Reflecting lamps 反射灯反射灯
Tungsten-halogen lampsTungsten-halogen lamps 卤钨灯卤钨灯
low-voltage bulbslow-voltage bulbs
Spot lamps Sealed beam lamps Crown-silvered lamps
7.1.3 Discharge lamps7.1.3 Discharge lamps 放电灯放电灯
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 7.2 Luminaires 灯具灯具
7.3 how to do Lighting design 7.3 how to do Lighting design 照明设计照明设计
First , find the standard service illuminance levels
Then , use Lumen method 流明法 to calculate the numb
er of lamps needed.
At the end of design, we place these lamps in a regul
ar grid pattern
LLFUFF
AEN
Practices in class
1 Modern sources of artificial light convert ( ) to ( )
A chemical energy
B electrical energy
C light energy
D heat energy
2 Oldest sources of artificial light convert ( ) to ( )
A chemical energy
B electrical energy
C light energy
D heat energy
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