A simplified daylight model suitable for daylight controllers - PREPRINT
Daylight Utilization
Transcript of 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
directionaldaylighting
8ono
directionaldaylighting
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law of =apan#aylighting
condition 1
idirectional
daylighting
8ono
directional
daylighting
8ono
directional
daylighting
#aylighting
condition 2
idirectional
daylighting
idirectional
daylighting
8ono
directionaldaylighting
#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
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#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'
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#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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