Light in architecture.

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LIGHT IN ARCHITECTURE STRATEGIES FOR DAYLIGHTING KUNAL NAVANDAR T.Y.B.ARCH RED BATCH - 17


TABLE OF CONTENTS 1. INTRODUCTION

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2. DAYLIGHTING IN A BUILDING

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2.1. INTRODUCING DAYLIGHTING STRATEGIES 2.2. DAYLIGHTING SYSTEMS 2.2.1. DAYLIGHTING SYSTEMS WITH SHADING 2.2.2. DAYLIGHTING SYSTEMS WITHOUT SHADING 2.2.3. TABLE FOR VARIOUS WINDOW SYSTEMS 2.3. DAYLIGHTING SYSTEM DETAILS 2.3.1. LIGHT SHELVES 2.3.2. LOUVRES AND BLIND SYSTEMS 2.3.3. PRISMATIC PANELS 2.3.4. LASER CUT PANELS 2.3.5. ANGULAR SELECTIVE SKYLIGHT 2.3.6. LIGHT GUIDING SHADES 2.3.7. SUN DIRECTING GLASS 3. CASESTUDIES

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3.1. SMALL HOUSE AT NORTHERN OREGON, U.S.A. 3.2 CNA-SUVA BUILDING 3.3 VAN ANDEL INSTITUTE 4. REFERENCES

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1. INTRODUCTION Daylight is an essential resource that is readily available – and unlikely to run out for the foreseeable future. It also has the very special characteristic of having the ability to transform an internal space from uninspiring uniformity into a psychologically uplifting experience. Daylight varies in intensity and quality from moment to moment and how much variation is desirable or can be tolerated will depend on the particular use of a space. Lighting requirements can be very strict for certain uses. However, to provide good lighting there are 3 factors that should always be considered: the quantity, quality of light and its distribution. Intense sunlight can lead to glare which can be both irritating and debilitating for a user’s task. thus controlling the admission of light requires careful disgn of openings.

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2. DAYLIGHTING IN A BUILDING 2.1. INTRODUCING DAYLIGHTING STRATEGIES Daylighting strategies depend on the availability of natural light, which is determined by the latitude of the building’s location and the conditions immediately surrounding the proposed building. Daylighting strategies are also affected by climate and it is important to identify seasonal variations, prevailing climate conditions, and sunshine probability. Knowing the climate, and the daylight availability at each façade of a proposed building, is an essential factor in the designing for daylight. High altitudes have distinct summer and winter conditions and in winter when daylight levels are low designers usually aim to maximize daylight penetration in a building. Redirecting daylight into buildings from the brightest regions of the sky is an appropriate strategy at these altitudes. By contrast, in the tropics, the design emphasis is usually on preventing overheating by restricting the daylight entering a building. 2.2. DAYLIGHTING SYSTEMS A daylighting system combines simple glazing with some other elements that enhances the delivery or control of light into a space. while ordinary windows deal adequately with some of the daylight needs of a space, there are new technologies and solutions that extend performance beyond that of the conventional solutions: 

Providing usable daylight at greater depths from the window wall than is possible with convention designs  Increasing usable daylight for all weather conditions  Transporting usable daylight to windowless spaces. These work by introducing reflective or refractive components into the glazing system. In addition they may or may not combine this with shading the interior from sunlight. 2.2.1. DAYLIGHTING SYSTEMS WITH SHADING Two types of daylighting systems with shading have been reviewed:  Systems that rely primarily on diffuse skylight and reject direct sunlight.  Systems that use primarily direct sunlight, sending it onto ceiling or to locations above eye height. Conventional solar shading systems, such as pull down shades, often significantly reduce the admission of daylight to a room. To increase daylight while providing shading, advanced systems have been developed that both protect the area near the window from direct sunlight and send direct/diffuse daylight into the interior of the room 2.2.2. DAYLIGHTING SYSTEMS WITHOUT SHADING Daylighting systems without shading are designed primarily to redirect daylight to areas away from a window or skylight opening. They may or may not block direct sunlight. These systems can be divided into 4 categories: 4


 

Diffuse light guiding systems redirect daylight from specific areas of the sky vault to the interior of the room. Under overcast sky conditions, the area around the sky zenith is much brighter than the area close to the horizon. Light-guiding systems can improve daylight utilization in these situations. Direct light-guiding systems send direct sunlight to the interior of the room without the secondary effects of glare and overheating. Light-scattering or diffusing systems are used in skylit or toplit apertures to produce even daylight distribution. If these systems are used in vertical window apertures, serious glare will result. Light transport systems collect and transport sunlight over long distances to the core of a building via fibre-optics or light pipes.

2.2.3 .Table lists the different types of window systems, and shows which climate they are suitable for, and where they are normally placed in a building. 1.SHADING SYSTEMS CATEGORY TYPE/NAME Prismatic Primary panels using diffuse skylight

SKETCH

CLIMATE All climates

LOCATION Vertical windows, skylights

Prisms and venetian blinds

Temperate climates

Vertical windows

Sun protecting mirror elements Anidolic zenithal opening

Temperate climates

Skylights, glazed roofs

Temperate climates

Skylights

Directional selective shading system with concentrating holographic optical element

All climates

Vertical windows, Skylights, glazed roofs

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Primary using direct sunlight

Transparent shading system with HOE based on total reflection Light guiding shade

Temperate climates

Vertical windows, Skylights, glazed roofs

Hot climates, sunny sky

Vertical windows above eye height

Louvres and blinds

All climates

Vertical windows

Light shelf for redirecting sunlight

All climates

Vertical windows

Skylight with laser cut panels

Hot climates, sunny skies, low altitudes All climates

Skylights

Light shelf

Temperate climates, cloudy skies

Vertical windows

Anidolic ceiling

Temperate climates, cloudy skies

Vertical faรงade above viewing window

Anidolic integrated system

Temperate climate

Vertical windows

Laser cut panels

All climates

Vertical windows, skylights

Anidolic solar blinds

Vertical windows

3. DAYLIGHTING SYSTEMS WITHOUT SHADING Diffuse light guiding systems

Direct light guiding systems

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Sun directing glass Scattering systems Light transport

All climates

Vertical windows, skylights

All climates

Vertical windows, skylights

Hellostat

All climates, sunny skies

Solar tube

All climates, sunny skies

Roof

2.3. DAYLIGHTING SYSTEM DETAILS 2.3.1. LIGHT SHELVES:          

A light shelf is a daylighting system, which is designed to shade and reflect light on its top surface and to shield direct glare from the sky. Best used on the building’s south side, in a predominantly clear sky climate. Consider using clearer glass above for high daylight admission and tinted glass below for glare control. It is mounted approximately horizontally either inside or outside a window or both and usually kept above eye level, dividing a window into a lower part with a view, and an upper clerestory above. The lower the height of a light shelf, the greater is the light reflected onto a ceiling, but also the incidence of glare is likely to increase. Light shelves inside a window decrease the total light in a room, but distribute it more evenly. External light shelves can increase the total light because they can increase the proportion of light that comes from high angles in the sky. Light shelves can be fixed or pivoted and may track the sun. The top of the shelf should be matte white or diffusely specular, and not visible from any Point in the room. The ceiling should be smooth and light-colored. Consider using more advanced shapes and materials to redirect sun, block direct sun, and control glare Section drawing illustrating a deep wall section providing some self-shading. This allows easy integration of a light shelf, creates surfaces that mitigate glare, Sloped surfaces also help soften glare. A blind or shade can be added in the clerestory to manage glare from a low sun angle.

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2.3.2. LOUVRES AND BLIND SYSTEMS:          

Louvres and blinds are traditional daylighting systems that can be applied for solar shading, to protect against glare and to redirect daylight. They are located on the exterior or interior of a window, or between the panes of glass. Depending on the slat angle, louvres and blinds partly or completely obstruct directional view to the outside. Under sunny conditions, blinds can produce extremely bright lines along the slats, causing glare problems. With blinds at a horizontal angle, both direct sunlight and diffuse skylight can increase window glare due to increased luminance contrast between the slats and adjacent surfaces. Tilting the blinds upwards increase glare as well as visibility of the sky; tilting the blinds downwards provides shading and reduces glare problems. Both louvres and blinds can increase the penetration of daylight from direct sunlight, and when skies are overcast, louvres and blinds promote an even distribution of daylight. Louvres and blinds can be fixed or pivoted (and may track the sun) and have a specular, matt finish, or be translucent. Some more advanced designs of blinds are designed specifically to redirect light to the ceiling using concave louvres with a specular upper surface. The use of louvers in place of a solid dropped edge or solid overhang provides diffuse natural light while still shading.

2.3.3. PRISMATIC PANELS:  Prismatic panels are thin, planar, sawtooth devices made of clear acrylic that are used in temperate climates to redirect or refract daylight.  When used as a shading system, they refract direct sunlight but transmit diffuse skylight,  They can be applied in many different ways, in fixed or sun-tracking arrangements, to facades and skylights and used to guide diffuse daylight.  If used for redirecting sunlight, prismatic panels designs may redirect some sunlight down wards, causing glare.  However, with a correct profile and seasonal tilting, these downward beams can be avoided.

PRISMATIC PANELS 8


2.3.4. LASER CUT PANELS:    

A laser cut panel is a daylight- redirecting system produced by making laser cuts in a thin panel made of clear acrylic material. The laser-cutting divides the panel into an array of rectangular elements. Each cut surface then becomes a small internal mirror that deflects light passing through the panel. An advantage of the panel is that in between the cuts, a view to outside of the window is maintained, although this is somewhat disorted.

2.3.5. ANGULAR SELECTIVE SKYLIGHT (LASER CUT PANELS) :    

An angular selective skylight is conventional clear pyramid or triangular type of skylight. Laser-cut panels are incorporated inside the clear outer cover forming double glazing. The primary function of this skylight is to provide relatively constant irradiance to the interior during the day and to reduce the tendency to overheat a building on summer days. The skylights are especially suited for natural lighting of ventilated or airconditioned buildings with extensive floor area and low-angle roof, such as schools and supermarkets.

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2.3.6. LIGHT GUIDING SHADES:  Light guiding shades are external shading system that redirect sunlight and skylight onto the ceiling.  They are designed to improve the daylighting of rooms in subtropical buildings that have often have deep external shading from wide eaves to reduce radiant heat gain through windows.  The shading system consists of a diffusing glass aperture and two reflectors designed to direct the diffuse light from the aperture into a building within specified angular range.  Compared to shading from an opaque overhang, the light guiding shade much improves the illuminance and its uniformity in the room interior.

2.3.7. SUN DIRECTING GLASS:  The main component of a sun-directing glass system is double glazed sealed unit that holds concave acrylic elements.  These elements are stacked vertically within a double glazed unit and redirect sunlight from all angles of incidence onto the ceiling.  The sealed unit is normally placed above the view window.  A sinusoidal pattern on the interior surface of the window unit can be used to spread outgoing light within a narrow horizontal, azimuthal angle.  A holographic film on the exterior glass pane can also be used to focus incoming daylight within a narrow horizontal angle.

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3. CASESTUDIES 3.1. SMALL HOUSE AT NORTHERN OREGON, U.S.A.

This small house is a contemporary glass box that floats atop the surrounding wheat fields of Northeast Oregon.

It’s overall design is inspired by the traditional architecture of barns and farmhouses in the Pacific Northwest – only wrapped up in glass.

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It is designed by Olson kundig architects

The house was planned as a sustainable structure, taking advantage of passive heating and cooling aspects; in winter time, its south facing orientation enjoys passive solar heat gain from the low-angled winter sun; in summer, roof overhangs and a light shelf block the high hot summer sun from entering, while large, operable windows provide cross-ventilation cooling, lessening the house’s need for air-conditioning.

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3.2 CNA-SUVA BUILDING

The prismatic panel reflects light to the desired angle. Location: Basel, Switzerland System: Prismatic panel in double envelope system Architect: Herzog and DeMeuron Renovation Completion: 1993 Project Description: The renovation of a low-rise office building in Switzerland by the addition of exterior layer of prismatic panels.

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    

The double-skin facade reduces heat losses in the winter and heat gain in the summer through optical control of sunlight. Within one floor height, the double-skin facade can be divided into three sections. The upper section is made of insulating glass with integrated prismatic panels which automatically adjusts itself as a function of the altitude of the sun. This panel has two functions: reflecting sunlight toward the outside and admitting daylight into the interior space. The vision window is made of clear insulating glass and is manually operated by the occupant during the daytime. The lower level window is automatically controlled to stay closed when solar and thermal insulation are desired.

3.3 VAN ANDEL INSTITUTE

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Location: Grand Rapid, MI System: Louvers façade

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4. REFERENCES  Daylighting in buildings- international Energy Agency ,Energy Conservation In Buildings And Communitys System Programmes PDF  High-Performance Commercial Building Façades PDF

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