Daylight Utilization

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Daylight utilization

Daylight utilization is technology aims to secure light during the day, a reduce

lighting energy consumption as well as increase occupant’s comfort3.2.1 Purpose and key points of daylight utilization

1. Skillfully introduction of daytime brightness into the room reduces

unnecessary use of lighting, which would enable to reduce lighting energy

consumption

2. The stark contrast in lighting between an opening and inside of the room will

result on daytime lighting, due to dark indoor condition despite sucient

daylighting

3. The daylight utiliation technology consist of !daylighting method" and

!daylight guiding methods"

3.2.2 Energy conservation target levels for daylight utilization

1. #e$nition

%e&el ' (ooling energy reduction )one%e&el 1 (ooling energy reduction *ppro+. 23 -%e&el 2 (ooling energy reduction *ppro+. -%e&el 3 (ooling energy reduction *ppro+. 1' -

2. /e0uirement

a Site condition

The possibility on sunlight utiliation &aries depending on the condition of

surrounding area. Such as building that interrupt the sunlight from entering to

the house.

%ocation 1 igh density, high rise location in which sunlight is hard to

utilie%ocation 2 igh density location in which sunlight can be utilied with

ingenuity%ocation 3 Suburban location in which sunlight can be easy to utilied

#aylight conditions

Table 1 4uidelines for daylighting conditions

%i&ing5dining

room

Senior’s5(hildre

n’s room

6ther

habitable

room

)on

habitable

room#aylighting

condition '7e0ui&alent with

building standard

8ono

directionaldaylighting

8ono


8ono


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Advance Building Environmental Engineering and Building Services

law of =apan#aylighting

condition 1

idirectional

daylighting

8ono

directional

daylighting

8ono

directional

daylighting

#aylighting

condition 2

idirectional

daylighting

idirectional

daylighting

8ono


#aylighting

condition 3

idirectional

daylighting

idirectional

daylighting

8ono

directional

daylighting

8ono

directional

daylighting)ote>

8ono and bi directional daylighting refers to the number of daylight utiliation

methods adopted.

3. ow to achie&ed target le&els

1. ow to achie&e the target le&els

Table 2 Target le&els for daylight utiliation and how to achie&e them.

%i&ing5dinin

g room

#aylighting conditions 7application of methods7%ocation 1 %ocation 2 %ocation 3

%e&el

'

)one #ay lighting

condition '%e&el

1

*ppro+. 23

-

#ay lighting

condition 3

#ay lighting

condition 2

#ay lighting

condition 1

%e&el2 *ppro+. - #ay lightingcondition 3 #ay lightingcondition 2%e&el

3

*ppro+. 1'

-

#ay lighting

condition 3

2. Types of daylight utiliation method and light en&ironment characteristic

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3.2.3 Steps for examining daylight utilization technology and

prereuisites

1. Steps for e+amining daylight utiliation technology

Step 1. (on$rming site and sunlight conditions

* Study the seasonal site and sunlight condition from the ?oor planningperspecti&e and consider a location that will continue to ensure the

sunlight in the future Study the seasonal site and sunlight condition from a sectional planningperspecti&e and framework of the three dimensional building shape,including the number of stories.

Step 2. @+amining direct daylight utiliation methods

* @+amine the position and shapes of the opening that enable daylighting.(onsider the relationship between daylight utiliation and wind utiliation.

@+amine the sun control system around the openings. (onsider therelationship daylight utiliation and solar shading

Step 3. @+amining indirect daylight utiliation methods

* @+amine daylight guiding methods according to the spatial structures anddaylighting methods

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8ake the daylight guiding plan feasible for entire space as much aspossible. @+amining the spatial connection such as partition walls andtheir types.

Step :. Adentifying areas lacking daylight and incorporation this into lightingsystem

* Adentify areas lacking daylight and incorporating this into lighting system

2.


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2. Sectional planning based on the site condition


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occupant’s comfort. To a&oid this, solar shading and sun control should be

planned together so that an appropriate le&el of daylight is achie&ed.

a. a The higher the position of the opening, the further the light reaches

in the room and the greater the uniformity of the indoor illuminanceb The higher the position of the window, the easier the protection of

pri&acy and the greater the tendency of opening the curtainsc The higher the position of windows, the further it is from the center

of the &isual $eld and ease the glare reduction.

Top side windows Top side windows might be greatly useful if the space between

buildings is narrow and the possibility of daylighting from side windows

is e+tremely low, or if there is north facing windows room re0uiredmore light.

b.


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Sun control eGect of o&erhangs

The sun control eGect of o&erhang is depend on the depth.

Higure a and b show the diGerences in the perception of light from the south

facing opening at noon. Since the solar altitude is high, deep o&erhang 7b

creates a large shady area and the glare of the opening is small.

Higure c and d show the perception of light from the east facing opening at ;.''

a.m. Since the solar altitude is lower than noon, the sun shines on the ?oor, but

deep overhang can reduce the glare area

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Sun control eGect of decorati&e openings

The sun control eGect with decorati&e opening fre0uently used in order to help

protect against hea&y wind and pro&ide aesthetic landscaping. An Higure b, the

decorati&e opening pre&ent the back of the room from looking dark by securely

blocking solar radiation.

Higure * 7without blocks of decorati&e opening

Higure 7with blocks of decorati&e opening

*nother e+ample of decorati&e opening

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Method 2. !ndirect daylight utiliation methods

a. #aylight guiding using spatial structures Transom windows

Similar to transom windows, glass block or glass screen in partition wall

guides daylight into the entire space.

%ight wells

The light well is used in the combination of top side windows or other

means.

b. #aylight guiding using re?ection on $nished surface 7 re?ection on outside

surface, back of ea&es and indoor surfaces

The fundamental of this methods are that the light re?ected on the ground

is re?ected further on the back ea&es and ceiling around the opening in

order to guide the light into the back of the room.

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c. #aylight guiding using de&ices

At is desirable that the light shelf installed at higher position than the eyele&el in order to secure &iew.

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Documents

Daylight Utilization