North light (architecture)

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North light (in the Northern Hemisphere) is sunlight coming through a north-facing window. Because it does not come directly from the sun, it remains at a consistent angle and colour throughout the day and does not create sharp shadows. It is also cooler than direct sunlight due to the way the Earth's atmosphere scatters light via Rayleigh scattering.

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These properties make it the natural light of choice in certain styles of architecture, [1] painting [2] and photography. [3] In addition, the cool colour of north light has been studied for its effect on our perception of art in galleries and museums.

South of the equator (in the Southern Hemisphere), the same characteristics are seen in south light.

Formation and properties

Because the sun passes to the south of most observers in the northern hemisphere, north light is the light coming from the sky, rather than directly from the sun. This is the reason for its diffused nature, as well as why it casts softer shadows than direct sunlight and remains more consistent in colour than light from the east or west (which would be affected by sunrise and sunset respectively).

The colour of diffused daylight is 5500 - 6500K, [4] meaning that north light is cooler (more blue tinted) than light from other directions. The main cause of this is Rayleigh scattering, which was first mathematically described by British physicist Lord Rayleigh (John William Strutt) in 1871. Earth's atmosphere contains large proportions of nitrogen and oxygen which, via Rayleigh scattering, scatter short wavelengths of electromagnetic radiation more efficiently than longer wavelengths. Thus, light scattered or diffused away from the main beam of sunlight appears cooler while direct light (especially during sunlight or sunset) appears warmer.

North light is also less bright than direct sunlight, as only a portion of incoming white light is scattered. The brightness of north light can be between 10,000 and 30,000 lux, depending on location and season, while direct sunlight can be as bright as 100,000 lux. [5]

In architecture

The use of natural light in architecture is called daylighting. [6] It first rose to professional importance during the Roman Empire, when architects struggled to improve the ambience of public and religious spaces while reducing glare. At first, this involved physical structures such as clerestory windows and roof slits, however by the first century CE the direction of light began to play a bigger role. The Pantheon, rebuilt during the reign of emperor Hadrian (117CE – 138CE) employs an oculus (roof window) to let in unobstructed but diffused light, much like a modern north-facing window or skylight would. [6]

Because the sun moves to the south of buildings in the Northern Hemisphere, the northern side of these buildings is always in the shade. For daylighting, this has certain implications:

In addition, the latitude of a building changes the effect of north light. Near the equator, the only difference between north and south light may be seasonal. In temperate regions, the implications above apply year-round. In polar areas, they may be even more extreme. For example, Anchorage in Alaska receives only five hours of sunlight at winter solstice, with the sun rising only 5.5 degrees above the horizon. This would make north-facing windows too dark to be of any use during winter.

Passive housing

Houses that rely on sunlight, wind and insulation to regulate their temperature (as opposed to artificial cooling and heating) are known as passive houses. Because of its lower brightness and lower amount of infrared radiation, north light transmits less warmth to buildings than direct sunlight does. This makes large north-facing windows better suited for passive houses in warm, tropical climates, as it allows living areas to receive ample sunlight without overheating the building. [10]

In painting

Rembrandt's Portrait of Johannes Wtenbogaert (1633) is an example of Rembrandt lighting - diffused light hits the subject from the viewers' left, but some is reflected back onto the subject, creating definition in the subject's face on the viewers' right. Rembrandt - Portrait of Johannes Wtenbogaert.jpg
Rembrandt's Portrait of Johannes Wtenbogaert (1633) is an example of Rembrandt lighting - diffused light hits the subject from the viewers' left, but some is reflected back onto the subject, creating definition in the subject's face on the viewers' right.

North light has been an important feature in painting studios before the development of electric lights, but its use continues to this day. Much like in architecture, light direction is important for the mood of a painting, but the light's ambience is even more critical. This is because rays of sun entering from the east, west and south change shape and direction during the day. A complex scene would be very difficult to paint while the shadows and reflections move. [11] Furthermore, accurately depicting harsh light requires a large dynamic range (difference in darkness between blacks and whites) which most traditional paints can not reproduce. [11]

Italian Renaissance painter Leon Battista Alberti alluded to this lack of dynamic range in 1435, writing that “no surface should be made so white that you cannot make it [...] whiter still”. [12] However, it was Leonardo da Vinci who first wrote about studio lighting in detail. By 1492 he had discovered the adaptation of the human pupil to darkness, noting that “the eye perceives and recognises the objects with greater intensity [when] the pupil is more widely dilated”. Following this, he painted in a dimly lit studio and avoided harsh southern light. The effects of this soft, dim lighting can be seen in later works such as the Mona Lisa. [12]

The use of specifically northern, rather than merely dim light became more common during the Dutch Golden Age with painters such as Rembrandt and Johannes Vermeer. [11] This can be seen in works such as Vermeer's The Milkmaid.

Direct sunlight casts sharp shadows such as these. As they create dark lines and move during the day, such lighting is often difficult for painters to work with. Sharp Shadows.jpg
Direct sunlight casts sharp shadows such as these. As they create dark lines and move during the day, such lighting is often difficult for painters to work with.

Artists without access to north facing windows have developed alternative solutions to replicate some of the desirable properties of north light for painting. These include:

However, due to the inverse square law, light falling on an object close to its source (e.g. from an artificial lamp) will decrease in brightness over a shorter distance than light falling on an object further away from its source (e.g. from a north facing window). This is known as falloff, and means that any artificial lighting used must be fairly powerful and positioned a long distance away from the subject in order to accurately imitate north light.

In photography

Photographers use north light for similar reasons as painters but have access to electric lights as well. The use of softboxes and bouncing speedlights against umbrella-shaped diffusers strives to recreate the soft shadows that north light produces. These processes are popular in portrait photography. [14]

The Dutch Golden Age of painting has also left a legacy – since the early 20th century, photographers and filmmakers have used Rembrandt lighting to return some dramatic effect to diffused light, both in portraits and cinema. [15] This entails a key light illuminating the subject (such as a north-facing window) and a reflector facing the other side of the subject. While this lighting was not formally named in Rembrandt's time, it appears in some of his paintings.

Like painters, photographers can modify south light or use artificial lighting as a replacement for north light if needed. However, they can also employ post production software such as Adobe Lightroom and Photoshop to correct exposure and temperature. In addition, dedicated software such as Robin Myers Imaging EquaLight [16] can adjust for lens and lighting falloff, which is especially useful for fine art photographers. [13]

Effect of art appreciation

Before artificial lighting, both the artist and their audience would both see art under natural light (either coming from the north or scattered in some way to reduce glare). However, since the 1980s museums and galleries have become reliant on some degree of electric lighting. [17] This means that the audience may see art differently to how it was intended and may also miss out on observing subtle changes in shadows and highlights as light moves throughout the day.

Studies into art perception have found that the colour correlated temperature (CCT) of north light (~6000K) may be too cool for optimum appreciation of most art. For example, a 2004 study found 3600K to be the preferred temperature – a warm CCT which is commonly used in museums. [18] A 2008 study by the Optical Society of America used different methodology to suggest 5100K as the optimal temperature [19] – although this is still slightly warmer than natural north light.

However, the most comprehensive study on this topic was done by the University of Vienna in 2019. It divided appreciation further into beauty, emotional arousal and interest, and studied both portraits and abstract art. While the findings for portraits suggest a warmer CCT in line with previous studies, a cooler CCT was preferred for abstract art. [20]

Related Research Articles

<span class="mw-page-title-main">Color temperature</span> Property of light sources related to black-body radiation

Color temperature is a parameter describing the color of a visible light source by comparing it to the color of light emitted by an idealized opaque, non-reflective body. The temperature of the ideal emitter that matches the color most closely is defined as the color temperature of the original visible light source. The color temperature scale describes only the color of light emitted by a light source, which may actually be at a different temperature.

<span class="mw-page-title-main">Rayleigh scattering</span> Light scattering by small particles

Rayleigh scattering is the scattering or deflection of light, or other electromagnetic radiation, by particles with a size much smaller than the wavelength of the radiation. For light frequencies well below the resonance frequency of the scattering medium, the amount of scattering is inversely proportional to the fourth power of the wavelength. The phenomenon is named after the 19th-century British physicist Lord Rayleigh.

<span class="mw-page-title-main">Daylighting (architecture)</span> Practice of placing openings and reflective surfaces so that sunlight can provide internal lighting

Daylighting is the practice of placing windows, skylights, other openings, and reflective surfaces so that direct or indirect sunlight can provide effective internal lighting. Particular attention is given to daylighting while designing a building when the aim is to maximize visual comfort or to reduce energy use. Energy savings can be achieved from the reduced use of artificial (electric) lighting or from passive solar heating. Artificial lighting energy use can be reduced by simply installing fewer electric lights where daylight is present or by automatically dimming or switching off electric lights in response to the presence of daylight – a process known as daylight harvesting.

<span class="mw-page-title-main">Kruithof curve</span> Region of color temperatures that are often viewed as pleasing to an observer

The Kruithof curve describes a region of illuminance levels and color temperatures that are often viewed as comfortable or pleasing to an observer. The curve was constructed from psychophysical data collected by Dutch physicist Arie Andries Kruithof, though the original experimental data is not present on the curve itself. Lighting conditions within the bounded region were empirically assessed as being pleasing or natural, whereas conditions outside the region were considered uncomfortable, displeasing or unnatural. The Kruithof curve is a sufficient model for describing sources that are considered natural or closely resemble Planckian black bodies, but its value in describing human preference has been consistently questioned by further studies on interior lighting.

<span class="mw-page-title-main">Lighting</span> Deliberate use of light to achieve practical or aesthetic effects

Lighting or illumination is the deliberate use of light to achieve practical or aesthetic effects. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight. Daylighting is sometimes used as the main source of light during daytime in buildings. This can save energy in place of using artificial lighting, which represents a major component of energy consumption in buildings. Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants.

<span class="mw-page-title-main">Sky</span>

The sky is an unobstructed view upward from the surface of the Earth. It includes the atmosphere and outer space. It may also be considered a place between the ground and outer space, thus distinct from outer space.

<span class="mw-page-title-main">Contre-jour</span> Photographic technique

Contre-jour is a photographic technique in which the camera is pointing directly toward a source of light, as well as an equivalent technique of painting.

<span class="mw-page-title-main">Diffuse sky radiation</span> Solar radiation reaching the Earths surface

Diffuse sky radiation is solar radiation reaching the Earth's surface after having been scattered from the direct solar beam by molecules or particulates in the atmosphere. It is also called sky radiation, the determinative process for changing the colors of the sky. Approximately 23% of direct incident radiation of total sunlight is removed from the direct solar beam by scattering into the atmosphere; of this amount about two-thirds ultimately reaches the earth as photon diffused skylight radiation.

<span class="mw-page-title-main">Skyglow</span> Diffuse luminance of the night sky

Skyglow is the diffuse luminance of the night sky, apart from discrete light sources such as the Moon and visible individual stars. It is a commonly noticed aspect of light pollution. While usually referring to luminance arising from artificial lighting, skyglow may also involve any scattered light seen at night, including natural ones like starlight, zodiacal light, and airglow.

<span class="mw-page-title-main">Tyndall effect</span> Scattering of light by tiny particles in a colloidal suspension

The Tyndall effect is light scattering by particles in a colloid such as a very fine suspension. Also known as Tyndall scattering, it is similar to Rayleigh scattering, in that the intensity of the scattered light is inversely proportional to the fourth power of the wavelength, so blue light is scattered much more strongly than red light. An example in everyday life is the blue colour sometimes seen in the smoke emitted by motorcycles, in particular two-stroke machines where the burnt engine oil provides these particles. The same effect can also be observed with tobacco smoke whose fine particles also preferentially scatter blue light.

<span class="mw-page-title-main">Day for night</span> Technique to film night scenes in daylight

Day for night is a set of cinematic techniques used to simulate a night scene while filming in daylight. It is often employed when it is too difficult or expensive to actually shoot during nighttime. Because both film stocks and digital image sensors lack the sensitivity of the human eye in low light conditions, night scenes recorded in natural light, with or without moonlight, may be underexposed to the point where little or nothing is visible. This problem can be avoided by using daylight to substitute for darkness. When shooting day for night, the scene is typically underexposed in-camera or darkened during post-production, with a blue tint added. Additional effects are often used to heighten the impression of night.

<span class="mw-page-title-main">Architectural lighting design</span> Field within architecture, interior design and electrical engineering

Architectural lighting design is a field of work or study that is concerned with the design of lighting systems within the built environment, both interior and exterior. It can include manipulation and design of both daylight and electric light or both, to serve human needs.

<span class="mw-page-title-main">Blue hour</span> Period of twilight in the morning or evening

The blue hour is the period of twilight when the Sun is at a significant depth below the horizon. During this time, the remaining sunlight takes on a mostly blue shade. This shade differs from the colour of the sky on a clear day, which is caused by Rayleigh scattering.

<span class="mw-page-title-main">Light tube</span> Architectural element

Light tubes are structures that transmit or distribute natural or artificial light for the purpose of illumination and are examples of optical waveguides.

<span class="mw-page-title-main">Glare (vision)</span> Bright light which impairs vision

Glare is difficulty of seeing in the presence of bright light such as direct or reflected sunlight or artificial light such as car headlamps at night. Because of this, some cars include mirrors with automatic anti-glare functions and in buildings, blinds or louvers are often used to protect occupants. Glare is caused by a significant ratio of luminance between the task and the glare source. Factors such as the angle between the task and the glare source and eye adaptation have significant impacts on the experience of glare.

<span class="mw-page-title-main">Anidolic lighting</span> Indoor lighting

Anidolic lighting systems use anidolic optical components to light rooms. Light redirected by these systems does not converge to a focal point or form an image, hence the name.

<i>Officer and Laughing Girl</i> Painting by Johannes Vermeer c. 1657

Officer and Laughing Girl, also known as Officer and a Laughing Girl, Officer With a Laughing Girl or, in Dutch, De Soldaat en het Lachende Meisje, is an oil painting on canvas executed ca. 1657 by the Dutch artist Johannes Vermeer. Its dimensions are 50.5 by 46 cm. It is now one of three pictures by Vermeer in The Frick Collection in New York.

<span class="mw-page-title-main">Sustainable lighting</span>

Sustainable lighting is lighting designed with energy efficient light sources. "There are simple design strategies and some materials that can facilitate the energy saving advantages of natural light. Light colored interiors and open floor plans are good choices. This approach also augments artificial light efficiency. Energy efficient lighting is not simply finding the most light for the least wattage or the longest lasting light bulb. Proper sizing of the light to the needs of the location and the tasks that will be performed, called task lighting, is an energy saving strategy."

<span class="mw-page-title-main">Skylight</span> Window in the ceiling-roof

A skylight is a light-permitting structure or window, usually made of transparent or translucent glass, that forms all or part of the roof space of a building for daylighting and ventilation purposes.

The artificial sky is a daylight simulation device that replicates the light coming from the sky dome. An architectural scale model or 1:1 full-scaled aircraft is placed under an artificial sky to predict daylight penetration within buildings or aircraft that subjects to different situations, complex geometries, or heavily obstructed windows. The concept of the artificial sky was derived due to heliodon’s limitation in providing a stable lighting environment for evaluating the diffuse skylight component.

References

http://vastulab.com/importance-of-north-light-in-building-architect-guide-to-construction/

  1. ↑ "Design - Piano Tone - 2006.0111". ArchitectureWeek. 2006-01-11. Retrieved 2012-07-07.
  2. ↑ ELAINE LOUIE (March 27, 2003). "CURRENTS: ARCHITECTURE; A Photo Studio Where Day Can Be Night - New York Times". The New York Times . Retrieved 2012-07-07.
  3. ↑ "Quick Photo Tip: North Light | Online Photography School". bpsop.com. Retrieved 2022-05-25.
  4. ↑ "Colour Temperature Explained - Definition, Guides & Examples". Reduction Revolution. Retrieved 2022-05-25.
  5. ↑ Spitschan, Manuel; Aguirre, Geoffrey K.; Brainard, David H.; Sweeney, Alison M. (2016-06-07). "Variation of outdoor illumination as a function of solar elevation and light pollution". Scientific Reports. 6 (1): 26756. Bibcode:2016NatSR...626756S. doi:10.1038/srep26756. ISSN   2045-2322. PMC   4895134 . PMID   27272736.
  6. 1 2 Nyole, Florence. "History of Daylighting: A comparative analysis across the periods".{{cite journal}}: Cite journal requires |journal= (help)
  7. 1 2 "Daylighting 101: Orientation". Harka Architecture. 8 February 2018. Retrieved 2022-05-13.
  8. ↑ Ando, Tadao (2020-10-07). "Entretien avec Tadao Ando". LC. Revue de recherches sur le Corbusier (2): 123. doi: 10.4995/lc.2020.14334 . hdl: 10251/152303 . ISSN   2660-7212. S2CID   225134636.
  9. 1 2 3 Chalk, Chris (2017-01-29). "Why Is Northern Light Best For Artists?". Chris Chalk - Art Studio. Retrieved 2022-05-25.
  10. ↑ "Orientation | YourHome". www.yourhome.gov.au. Retrieved 2022-05-25.
  11. 1 2 3 Janson, J. "Vermeer's Studio". Essential Vermeer.
  12. 1 2 Filipczak, Z. Zaremba (December 1977). "New Light on Mona Lisa: Leonardo's Optical Knowledge and His Choice of Lighting". The Art Bulletin. 59 (4): 518–523. doi:10.2307/3049706. ISSN   0004-3079. JSTOR   3049706.
  13. 1 2 "On Fine Art Reproduction… (or: How to Do It Right) Part 5". Ted Dillard. 2011-10-26. Retrieved 2022-05-25.
  14. ↑ Valenzuela, Roberto (2015-03-15). Picture Perfect Lighting: An Innovative Lighting System for Photographing People. Rocky Nook, Inc. ISBN   978-1-68198-106-2.
  15. ↑ Jacobs, Lea (1993). "Belasco, DeMille and the Development of Lasky Lighting". Film History. 5 (4): 405–418. ISSN   0892-2160. JSTOR   27670733.
  16. ↑ "Robin Myers Imaging: EquaLight™". www.rmimaging.com. Retrieved 2022-05-25.
  17. ↑ Cannon-Brookes, S. (2000-01-01). "Daylighting museum galleries: a review of performance criteria". Lighting Research and Technology. 32 (3): 161–168. doi:10.1177/096032710003200311. ISSN   1477-1535. S2CID   110758405.
  18. ↑ Scuello, Michael; Abramov, Israel; Gordon, James; Weintraub, Steven (April 2004). "Museum lighting: Optimizing the illuminant". Color Research & Application. 29 (2): 121–127. doi:10.1002/col.10231. ISSN   0361-2317.
  19. ↑ Pinto, Paulo Daniel; Linhares, João Manuel Maciel; Nascimento, Sérgio Miguel Cardoso (2008-02-11). "Correlated color temperature preferred by observers for illumination of artistic paintings". Journal of the Optical Society of America A. 25 (3): 623–630. Bibcode:2008JOSAA..25..623P. doi:10.1364/josaa.25.000623. ISSN   1084-7529. PMID   18311230.
  20. ↑ Pelowski, Matthew; Graser, Andrea; Specker, Eva; Forster, Michael; von Hinüber, Josefine; Leder, Helmut (2019). "Does Gallery Lighting Really Have an Impact on Appreciation of Art? An Ecologically Valid Study of Lighting Changes and the Assessment and Emotional Experience With Representational and Abstract Paintings". Frontiers in Psychology. 10: 2148. doi: 10.3389/fpsyg.2019.02148 . ISSN   1664-1078. PMC   6788350 . PMID   31636577.
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