3 designing with natural light by dr acharawan chutarat

Designing with natural lightDr.Acharawan Chutarat,

School of Architecture + Design, KMUTT

of the perception of our surroundings are visual!

Daylight – Is good daylight important?

Of our time we stay in interior spaces!


What does good daylighting mean?


Certain Key benefits of daylight are as follows:

Improved lighting quality: Lighting quality refers to visual performance, visual comfort and ease of seeing. Daylight is a full spectrum source of visible light. Daylight can also provide any illumination level through proper design.

Human Comfort: Another aspect of daylight is its variability throughout the day, leading to peaked visual interest. The eyes adapt easily to gradual illumination changes, changes not easily attainable with artificial light. Research has suggested a positive biological response to daylight variability.

Increased Productivity: People exposed to daylight are more productive, more efficient, miss less work (or school) due to illness, buy more and will even be more creative. By far the largest cost in any office building is the personnel cost, which over time can outweigh even the capital cost of the building. Satisfied workers are more productive and the potential health and performance benefits associated with daylightingcould translate into significant productivity savings for a company over time.

Reduced auxiliary lighting load: Daylighting has become a major feature in energy efficient design. In commercial buildings, interior lighting accounts for about 30 to 40% of electricity consumption.

Reduced peak electricity demand: Daylighting is particularly well suited to commercial buildings, since those buildings are usually occupied during the day when natural light is available.

Daylight – Benefits of daylight

Source : Internet, NASA

Daylight – Visible wavelengths

In central Germany, an average of 950 and 1000 kWh/㎡ of sun energy is recorded each year. These values in Europe range from 850 kWh/㎡ in Northern Sweden to 1750 kWh/㎡ in Portugal.

Source : Dirk Seifert

Daylight – Solar radiation and energy

Source : Ehling, Dr. Karsten, Daylight Module Powerpoint, Lichtvision GmbH, May 2010

Daylight

Source : Ehling, Dr. Karsten, Daylight Module Powerpoint,Lichtvision GmbH, May 2010

Source : Brandi, Ulrike; Lighting Design

Source : Daylight Design for Buildings

Daylight – Daylight composition

Sun + sky

sun+sky+reflected

Daylight – Sun and atmosphere

Throughout history, daylight has been a crucial factor in the design of buildings. To quote Louis Kahn, one of the 20th century’s foremost architects, “I can’t define a space really as a space, unless I have natural light….natural light gives mood to space by nuances of light in the time of day and season of the year as it enters and modifies the space.“To Design a Space is to design light”

Daylight – Role of Daylight

Image: Merete

Balancing design objectives (William Lam, 1985)

“Designers must learn to design with concept that can be judged with their brains and eyes rather than with instruments”

Bill Lam, 1985

In workable areas, light that enters the space should have a daylight factor no less than 0.9%

EiD = x 100%

Ea

Ei – Interior Illuminance

Ea – Exterior Illuminance (overcast sky)

Source : Ehling, Dr. Karsten, Daylight Module Powerpoint,Lichtvision GmbH, May 2010

Daylight – Daylight factor equation

DF Limitations: Assume‐‐No direct sunlightLambertian surfaces (perfectly diffuse surface)Measured at center of a window

A critical issue that arises in side litspaces is that the daylightdistribution is not uniform fallingoff rapidly as one move away fromthe opening.

Source : Daylight design of buildings)

Daylight – Daylight distribution

Source : Daylighting and window design, Lighting Design Guide

Daylight – Building depth

Characteristic distribution of D with side window.Requirements for work stations: D> 1%

Characteristic distribution of D with roof lights.Requirements for work stations: Dm> 4%Dmin / D max > 0.5

D increases approx. linear with size of window.

Interior space and overcast sky

Daylight factor

Evaluation of indoor daylight situation by daylight factor

daylight factor

Zone of the room

impression of brightness

visual impression of the room

athmosphere

< 1% > 1% < 2%

> 2% < 4%

> 4% < 7%

> 7% < 12%

> 12%

very low low moderate medium high very high

far away from the window3 or 4 times of the window height

close to the window

dark very brightbright

this zone…….………...……seems to be separated………………from this zone

the room seems to be closed the room opens to the exterior

source: Bundesamt für Konjunkturfragen, „Ravel, Licht, Grundlagen der Beleuchtung“, 1994

When sunlight hits a pane of glass, it is split into three components ‐ that which is reflected, that which is absorbedand that which is transmitted through.

Source : Window systems for high performance buildings

Daylight – Glass

By adding a protection film or coating the glass has a higher reflectance value, lower the transmission of energy from one space to another.

Daylight – Sun protection glass



There are certain properties of windows that are the basis for quantifying energy performance:

U‐value: A measure of heat transfer through a glazing per degree temperature difference across the window expressed in W/(m2K).

Solar Heat Gain Coefficient (SHGC): This parameter is a ratio of total transmitted solar heat to incident solar energy for a glazing. The ratio ranges between 0 and 1 and is an indication of the total heat transfer of the sun’s radiation.

Visible transmittance (VT): A measure of the fraction of visible light that passes through a glazing.

Daylight – Glass transmission values

Daylight harvesting ‐ Light wells, Parabolic collectors, Light shelves, Reflective louvers

Source : Dr David Suzuki, Daylight and Daylight Harvesting

Daylight – Transporting light into a building

Daylight reflected across light shelves and interior surfaces

Reflecting daylight with louvres

a.

b.

Source : Daniels, K. – Technologie des ökologischen Bauens,Basel,Boston,Berlin 1995, S.148, Abb.182 ‐ 183

Daylight – Controlling daylight

By directing sunlight to the ceiling the light can be distributed across the surface at a uniformed level. A controlled light distribution in a room helps create a harmonious atmosphere within the space.

Source : Köster Lichtplanung ‐ RetroLight

Daylight – Light distribution within a room

By changing the louvres, light can be controlled to reflect away and help with reducing the glare.

Source : Köster Lichtplanung ‐ RetroLux

Daylight – Louvre systems

Semi transparent prisms can beused as a way to effectively controlthe seasonal changes of daylight.The prisms are arranged torespond to the sunlight, where thehigh summer sun is internallyreflected away from the prisms andthe low winter sun is reflectedwithin the building.

Source : Inglas Prismen

Daylight – Light shelves

Osuna Housing, Seville

Daylight – Shading

Once the window area has been fixed, the principal visual determinants of window shape and position are:— View— Visual comfort— Distribution of daylight.

There is a conflict between providing visual comfort, view and daylight access:

—Visual comfort requires little or no visible sky; direct sunlight in the field of view is especially undesirable.

—View favours an unhindered view of the skyline, but beyond this any additional skylight does little to enhance the view.

—Daylight requires access to plenty of open skylight.

Daylight – Position of windows

Source : Daylighting and window design

Daylight – Views

Windows present a fundamental conflict of objectives. On the one hand they let in daylight and provide views. On the other hand they also suffer from solar gains in summer, glare and even heat losses in winter. Glare and unwanted solar gains are usually dealt with by shading devise (also referred to as solar controls), but frequently these devices also interfere with the light‐admitting function.

It is a frequent sight, on sunny days, to see the blinds drawn and the artificial lights on. There is no shortage of daylight, rather a problem with its control and distribution.

The key feature of shading systems is that they offer the opportunity to reduce solar gain by blocking direct sunlight at the same time having a less of an effect on the penetration of skylight to the interior.

The Sun represents one of the most important sources of sustainable energy that we have at our disposal as designers. Thus the use of shading systems stems from their daylight benefits along with energy efficiency advantages.

Daylight – Shading design

Light Zone analysisSource: Jade and Piew

Image: Merete

Visual comfort also depends on position and direction of observer

Source: Boky and Mo

“Wedge of Light” WTC, NY

Source from Architecture Now! 3

Source from Architecture Now! 3

Boonserm Premthada

Thank you

Acharawan Chutarat

3 designing with natural light by dr acharawan chutarat

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