Daylighting

• Fisika Bangunan Terapan

DAYLIGHT vs SUNLIGHT

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DAYLIGHT vs SUNLIGHT

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DAYLIGHT vs SUNLIGHT

DAYLIGHT vs SUNLIGHTSunlight • The sunlight offers a moving directional light source. • the sunlight intensity always change; 5 to 10 x more intense

than daylight• the orientations always changing periodically (use sun path

or protractor) • the sunlight brings heat penetration into the room, etc.

Manage sunlight for• creating decorative Focal Points of room, such as stained

glass windows,or• illuminate and emphasize objects or surfaces, such as

fountain or ornamental walls

DAYLIGHT vs SUNLIGHT

Daylight• the daylight intensity always change, but has a

mean intensity (90%). E.g: Indonesia use 10000 lux as Langit Perencanaan.

• the daylight don’t have direction, so that need to be directed.

• the daylight don’t bring heat into the room.

Manage daylight for lighting the room (at day).

DIAGRAM

daylight

About 1/5 of sunlight illuminance

overcast

Direct 80%

sunlight

clear

horizon

zenith

DAYLIGHT dipengaruhi oleh

• Kondisi Awan (overcast sky, partly cloudy, clear sky)

• Posisi matahari (azimuth dan altitude)• Musim• Kandungan uap air di udara

Lθ = Lz (1 + sin θ) , shg luminasi daylight pd zenith adl 3x luminasi pd horizon (overcast sky)

3

Moon & Spencer, 1942

DAYLIGHT di Indonesia

Mengikuti hasil pengukuran Suryawinata 1974, • Utk ketinggian matahari mulai 60°, distribusi luminasi

untuk overcast sky, akan mendekati persamaan di atas. Sedang utk ketinggian matahari kurang dari 60°, posisi matahari akan sangat mempengaruhi distribusi luminasi terutama pada azimuth.

Mengikuti penelitian Adhiwiyogo 1969, Suryawinata 1974,• Langit perencanaan di Bandung, nilai stabil 90% adalah

overcast sky dengan luminasi ≥ 10.000 lux (hanya dari cahaya langit)

• Angka ini dipakai untuk seluruh Indonesia, sebelum ada penelitian yang valid untuk wilayah tertentu.

DAYLIGHT FACTOR (DF)

• Berhubung besarnya cahaya langit yang selalu berubah-ubah, maka untuk menyatakan tingkat pencahayaan dari langit di dalam bangunan digunakan suatu ratio yang disebut Faktor Pencahayaan siang hari (FP) atau Daylight Factor (DF) yaitu

“Perbandingan tingkat pencahayaan pada suatu titik pada bidang tertentu dalam suatu ruangan yang ditimbulkan oleh cahaya langit dengan suatu distribusi luminasi tertentu, terhadap tingkat pencahayaan pada bidang horisontal dari cahaya langit di tempat terbuka, pada saat yang sama” dimana kedua tingkat pencahayaan tsb tidak memperhitungkan cahaya matahari.

DAYLIGHT FACTOR (DF)

DF biasanya dinyatakan dalam persen sbb :

DF = Ei x 100 %

Eo• Ei = level pencahayaan dari langit pada suatu

titik pada suatu bidang di dalam ruangan (lux)• Eo = level pencahayaan dari cahaya langit pada

bidang horisontal di tempat terbuka (lux)

Besarnya DF ditentukan olehKomponen Langit(FL), Komponen Rg Dlm, Komponen Rg Luar

DF untuk aktivitas ruang

Task fc (lux) 10-20Lat. 30 Lat. 50 Lat.Lobby, offices general

10-20 (108-215) 0.5 – 1 1 – 1.5 2 – 3.5

Hotel rooms,

Conference,

Library stacks

20-50 (215-538) 1.5 – 3 1.5 – 4 3.5 – 9

Reading,

Drafting, Sewing, Sports-indoor

Science lab

50-100 (538-1076)

3 – 6.5 4 – 8 9 – 17.5

Principle of Overhang to Daylight Distribution

no overhang

• The curves indicate light levels. Overhangs reduce light and glare near the window, creating a softer gradient in the rooms

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2

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louvers

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• Break up the overhang for better distribution

Sidelighting (areas to be served by daylight) --overcast sky

d

1.5 d

d

1.5 - 2 d

daylighted zone

daylighted zone

Light-shelf

Side lighting (areas to be served by daylight) -- overcast sky

core

Less effective area

Effective areas within daylight 1.5 d

1.5 d

d

Daylight Rule of Thumb (DF-overcast sky)

Side lighting (areas to be served by daylight)

For spaces with sidelighting :

• DF av = 0.2 window area

• DF min = 0.1 window area

floor area

floor area

DF = daylight factorWindow area = total window areaFloor area = total areas to be served by 1.5d

Mechanical and Electrical Equipment for Building 7th ed. p.161

Soal• Lobby kantor dg ukuran 5 m x 6 m memiliki sisi dinding yang berjendela seluas

12 m2 di satu sisi-nya seperti pada gambar. Berapakah jarak dari jendela, yang masih memungkinkan aktivitas penglihatan di ruang tsb?

(DF lobby = 0.5 -1)

6.00

Denah

5.00

1.5 d

Side lighting

DF ave. = (0.2 x window area) / floor areaFloor area = 1.5 d x 5 = 4.5 x 5 = 22.5m2DF ave. = (0.2 x 12) / 22.5 =0 .1067

0.5 = (0.2 x 12) / floor area; Floor area = 4.8; maka jarak dari jendela= 4.8 / 5 = 0.96 m

DF ave. = (0.2 x window area) / floor areaPotongan

d=3.00

Clerestory / vertical monitors (areas to be served by daylight)

For spaces with toplighting / vertical monitors :

DF av = 0.2 skylight glazing area

floor areaDF = daylight factor

Skylight glazing area = total windows

Floor area = total area to be served by daylight

Daylight Rule of Thumb (DF-overcast sky)

Skylight (area to be served by daylight)

Horizontal skylight

DF av. = 0.5 skylight glazing area floor area

DF = daylight factorSkylight glazing = total windowsFloor area = total area to be served by daylight

Daylight Rule of Thumb (DF-overcast sky)

Net Glazing Areas• Required Net Glazing Areas=

2 x DF ave Total area ofInterior surfaces

x 1 - Area weightedave.reflectance of all interior surfaces

x

Visible Transmittance Vertical angle of sky visiblefrom center of window

1 23

54

x

1 Average Daylight Factor• If low-light spaces are desired ; DF = 1• If average spaces are desired ; DF = 2• If bright spaces are desired ; DF = 4

Daylight Planning

Total Area of Interior Surfaces

Add up total surface area of walls, ceiling and floor

2

Daylight Planning

Area Weighted Average Reflectance of all Interior Surfaces

Between 0 and 1. Add up total surface area of walls, ceiling, floor, windows, partitions, furniture and calculate weighted average reflectance (see equation)

3

Area weightedave. reflectance

Wall area x wall reflectance

Total surface area Total surface area= +

Ceiling area x ceiling reflectance

+ …etc.

Use 0.5 as default

Visible Transmittance ( VT)Daylight Planning

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Generic glazing types(1/4 “panes) Typical VTDouble pane clear 0.8Double pane tint-green or blue green 0.65Double pane tint – blue 0.51Double pane tint – bronze 0.47Double pane tint – gray 0.39Double pane low reflective 0.30Double pane medium reflective 0.20Double pane high reflective 0.10Double pane low-e clear 0.70Double pane low-e tint-green or blue-green 0.63Double pane low-e tint-blue 0.49Double pane low-e tint-bronze 0.45Double pane low-e tint-gray 0.37Suspended low-e film products 0.27 – 0.6

Or use 0.7 for small windows, 0.5 for medium windows, 0.3 for large windows

Vertical Angle of SkyDaylight Planning

5

• Estimate the angle as shown, from center of window.• Value between 0 and 90. • If no obstruction, vertical angle is 90.

horizon

Source : A sequence for daylighting design – J.Lynes, Lighting research and technology,1979

sistem di dalam bangunan

• Structural s

• Envelope / selubung e

• Mechanical m

• Interior i

Dalam bangunan, sistem-sistem tsb saling

berhubungan/terkait sehingga tercapai

efektivitas, efisiensi, serta estetika.

hubungan antar sistem

• Remote

• Touching

• Connected

• Meshed

• Unified

tetrahedron

Remote (berjauhan)• Level yang paling rendah, sistem-sistem

secara fisik berjauhan, tapi terkoordinasi dalam fungsinya.

Touched (bersentuhan) Salah satu sistem menumpang di atas yang

lain, terutama oleh karena gravitasi.

Connected (terhubung) Sistem yang satu terhubung pada yang lain

dengan paku, baut, terjepit, penggantung, perekat, dsb..

Meshed (bertautan)• Sistem-sistem menempati tempat yang sama

Unified (menyatu)• Sistem-sistem berbagi bentuk fisik yang sama

dan tidak lagi bisa dibedakan.

Kimbell Art Museum FortWorth, Texas

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a=sheet lead roof b=acrylic skylightsc=post-tensioned concrete shelld=reflectors e=supply ductworkf=incandescent track g=wood floringh=return air ducts i=exposed concrete masonryj=waffle slab k=travertine infill

Kimbell art museum – Fort worth, Texas

Exhibition Hall Turin

Railway Platform, Rotterdam

Kualalumpur International Airport

a=hypar shell roof b= triangular skylight trusses c=steel plate ceilingd=TL lighting track e=RC columnf=aluminium & glazing wall