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