window design for daylighting

8/13/2019 Window Design for Daylighting

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Window Design

ForDaylighting

Lighting & Acoustic

B.Arch - 2nd Year

Lecture by : Ar.Ashish Pant


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Effectiveness of Windows for daylightEffectiveness of Windows for daylight

depends on :depends on :

1. Weather & Location

2. Room Proportion

3. Room Reflectance

4. Building Massing & Shape

5. Ceilings


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WEATHER DATA & LOCATION


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ROOM PROPORTIONProportion, not size determines light distribution


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ROOM REFLECTANCELight distribution is highly dependant on

room reflectance, primarily walls and ceiling.


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BUILDING SHAPE AND MASSING

When using sidelighting only,

in general, a narrow form has the greatest access

to exterior openings and will be the easiest to illuminate.


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CEILINGSIn general, ceilings are the most effective light-reflecting and

light-receiving surfaces. It should be unobstructed, of high

reflectance, and seen by most horizontal task areas.

1.Increase the distance between

task and ceiling to allow the task

to see more ceiling.

2. Increase the distance between

light source and ceiling to

distribute light more evenly

across the ceiling.


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CEILINGS

3. Use low windows and ground-

reflected light, but be careful to avoidglare at eye level.

4. Use high-reflectance

Surfaces.

5. Shape ceiling formin. surfaces and use

smooth surfaces.


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Design Issues for Side lighting throughDesign Issues for Side lighting through

Windows :Windows :

1. Location of Openings

2. Shape of Openings

3. Number of Openings

4. Shading Devices

5. Sunlight Redirecting Devices

6. Shutters, Blinds, and Screens


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OpeningsThe location of openings affects both light distribution and the

perception of distribution.


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Openings-Upper SectionThe upper window sees the brightest zenith of the overcast sky and

therefore has the best distribution of light on overcast days. Upper

windows have potential for sun and sky glare so should beproperly baffled.


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Openings-Middle SectionThe middle window is not optimal for light distribution on sunny

days or overcast days, yet it is the most commonly used location

because of the view afforded. Again,glare is a problem that must be dealt with.


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Openings-Lower SectionThe lower window provides optimal distribution of reflected sunlight.

This is because it maximizes the distance between the light source and

the ceiling and provides the greatest uniformity. The lower window

will typically not be a source of direct glare, but can be a source of

reflected glare when located below eye level.


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Openings-Lower SectionThe value of the view out a low window depends on its scale. The

view from the bottom third of a 24-foot wall can be very good, but

the view from the bottom third of a 9-foot or 12-foot wall withthe window head only 3-4 feet above the floor is likely to be

unsatisfactory.


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Openings-Near Interior WallsVertical high-reflectance walls can also be utilized as a surface to receive and

redistribute sunlight. These windows will encourage distribution while

minimizing shadows, and reducing glare and contrast between the opening and

the interior. Walls are especially useful for controlling low-angle (horizontal)

sunlight, which is difficult to redirect to the ceiling.


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Shape of Openings-Displacement1. Projecting lower sills will maximize illumination from area sources

such as overcast skies. It should be used in orientations that do not

require shading.

2.The overbite configuration is best for ground-reflected sunlight and

shades direct sun and skylight.


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Shape of Openings-WallsSills which slope to the exterior will minimize the possibility of glare

from the sill and will allow penetration of ground-reflected light.

These sills are not good at reducing contrast on the interior orbouncing light deeply into space.

Sills which slope or curve onthe interior will create intermediate gradients of light that effective

soften a contrast between interior and exterior. They can also bo

light deep into a space.


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Multi lateral OpeningsIn general, locating openings in more than one wall will enhance

the distribution of light. Light coming from multiple directions helps

provide a softer, more diffuse light with less shadows and

silhouetting.


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Shading Devices-HorizontalHorizontal devices provide shade based on the altitude angle of the

sun. They let in low-angle sunlight and block high-angle

sunlight; their effectiveness varies seasonally with the changing

solar altitude.

Most commonly seen in the form of overhangs, they are particularly

effective for shading north and south elevations.


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Shading Devices-VerticalVertical devices provide shade based on the bearing angle of the sun.

Their effectiveness varies diurnally, as the sun moves around the

horizon.

Vertical devices have the ability to block low-angle sun, and

consequently they are often used on openings facing east or west.


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Shading Devices-Egg-CrateEgg-Crate shading devices combine the characteristics of vertical and

horizontal devices to improve the shading coverage.


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Sunlight-Redirecting Devices-Light ShelvesLight shelves are horizontal shading and redirecting devices. They

effectively create two apertures in a window wall, an upper clerestory

window which is primarily for illumination and a lower window for view.

For best distribution, light shelves should be located as low in a space

as possible without causing glare, typically above standing eye level.


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Sunlight-Redirecting Devices-Light ShelvesTo be effective, the minimum depth of a light shelf is determined by

hading requirements. To prevent glare conditions, direct light from t

upper window should not penetrate past the edge of the light shelf.


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Sunlight-Redirecting Devices-Light Shelves


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Sunlight-Redirecting Devices-Light ShelvesThe location of the glazing affects the amount of solar radiation admitted

into a building. Recessed glazing has shade throughout the year; glazing

flush to the exterior maximizes heat gain. For buildings with seasonal

heating requirements, the glazing should be located midway.

Note: light shelves are most effectiveon the south side. To achieve effective

shading, on the east and west sides they

can be augmented with vertical devices,

or additional horizontal louvers. Light

shelves are not useful for light distribution

on the north side, but they do not

substantially

reduce illumination and may make views

more comfortable by blocking sky glare.


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Sunl ight-Redirecting Devices-Suncatchers

Suncatchers are vertical sunlight-redirecting devices parallel to the

building faade. They are best for intercepting low-angle sunlight

on the east and west sides of buildings. They also catch sunlight on the

North side of buildings, substantially increasing the illumination.

Note: light which they catch

tends to be reflected downward,

which can result in glare.

Therefore,

they should be used to redirect

lighttoward walls or, in conjunction

with

a light shelf, to redirect the light

toward the ceiling.


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Five Basic Strategies to PromoteFive Basic Strategies to Promote

Effective Use of Daylight :Effective Use of Daylight :

1. Maximize solid angle of sky seen from the task

2. Shade to prevent glare

3. Do not block light

4. Locate openings high

5. Shape space to minimize absorption of light


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Light tubeLight tube


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Assignment No. : 2

Q1. Explain the concepts adopted, the benefits, the design

recommendation , the materials used and the methods of construction

for an effective Daylighting design.

Q2. Describe with sketches strategies that you would use for distribution of

daylight in the interiors of a multi level office building.

Q3. With the help of a diagram, explain admission of diffused light in an

industrial building.

Q4. Mention the criterias considered while designing daylighting. Elucidate

with examples, the benefits of daylighting with materials and methods

used as design considerations and recommedations.

Q5. Mention and explain the lighting design strategies that an architectneeds to keep in mind and also provide for while designing spaces.

window design for daylighting

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