View source for Architectural lighting design

{{Short description|Field within architecture, interior design and electrical engineering}}
{{Use American English|date=March 2023}}
{{Use mdy dates|date=March 2023}}
[[File:Sangshad inside.jpg|thumb|upright|Play of light inside [[Jatiyo Sangshad Bhaban]]]]
[[File:Lloyds building, London at night.jpg|thumb|upright|Exterior lighting of the [[Lloyd's building]] in London]]

'''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.<ref name="Basic Concepts">{{cite book |title=Lighting: Basic Concepts |editor=Warren G. Julian |publisher=University of Sydney}}</ref><ref>{{cite web |url=https://www.newschool.edu/parsons/mfa-lighting-design/ |title=Lighting Design MFA |website=Parsons School of Design |access-date=January 21, 2021 }}</ref>

Lighting design is based in both [[science]] and the [[visual arts]].  The basic aim of lighting within the built environment is to enable occupants to see clearly and without discomfort.<ref name="Basic Concepts" /> The objective of architectural lighting design is to balance the art and the science of lighting to create mood, visual interest and enhance the experience of a space or place whilst still meeting the technical and safety requirements.<ref>{{cite web |title=Light in the Built Environment |url=https://www.light2015.org/Home/WhyLightMatters/Light-in-the-Built-Environment.html |date=June 1, 2015 |website=International Year of Light |access-date=January 21, 2021 }}</ref><ref>{{cite web |title=Definition of Architectural Lighting Design by KTH Royal Institute of Technology in Stockholm |url=https://www.kth.se/en/studies/master/architectural-lighting-design/description-1.7255 |website=KTH Royal Institute of Technology |access-date=January 19, 2021 }}</ref><ref>{{cite news |url=https://www.alconlighting.com/blog/lighting-design/what-are-architectural-lighting-fixtures/ |title=What Is Architectural Lighting |date=October 23, 2017 |website=AlconLighting.com |access-date=January 19, 2021 }}</ref>

== Overview ==
[[File:VIPlibrary.jpg|thumb|The predominantly [[Daylighting (architecture)|daylit]] auditorium of the [[Vyborg Library|Viipuri Municipal Library]] in the 1930s]]

The purpose of architectural lighting design is to balance the characteristics of light within a space to optimize the technical, the visual and, most recently, the non-visual components<ref>{{cite magazine |last=Zielinska-Dabkowska |first=Karolina |date=December 12, 2018 |title=Human Centric Lighting – The New X Factor? |url=http://www.arc-magazine.com/human-centric-lighting-the-new-x-factor/ |magazine=Arc Lighting in Architecture |location=UK |publisher=[D]arc-Media |access-date=January 23, 2021 }}</ref> of [[ergonomic]]s with respect to illumination of buildings or spaces.<ref>{{cite magazine |last=Skansi |first=Ranko |date=January 2020 |title=The Ergonomics of light |url=https://pld-m.com/en/article/research/the-ergonomics-of-light |magazine=Professional Lighting Design Magazine |location=Germany |publisher=VIA-Verlag |access-date=January 23, 2021 }}</ref>

The technical requirements include the amount of light needed to perform a task, the energy consumed by the lighting within the space and the relative distribution and direction of travel for the light so as not to cause unnecessary glare and discomfort.  The visual aspects of the light are those that are concerned with the aesthetics and the narrative of the space (e.g. the mood of a restaurant, the experience of an exhibition within a museum, the promotion of goods within a [[retail]] space, the reinforcement of corporate brand) and the non-visual aspects are those concerned with human health and well-being.<ref name="Karlen 2017">{{Cite book |last1=Karlen |first1=Mark |last2=Spangler |first2=Christina |last3=Benya |first3=James R. |date=2017 |title=Lighting Design Basics |url=http://worldcat.org/oclc/1021225843 |edition=Third |publisher=[[Wiley (publisher)|John Wiley & Sons]] |isbn=978-1-119-31227-7 |oclc=1021225843 }}</ref>

As part of the lighting design process both cultural and contextual factors also need to be considered. For example, bright lighting was a mark of wealth through much of Chinese history,<ref>{{cite news |last=Campanella |first=Thomas J. |title=Mapping the Edison Bulbs of Brooklyn |url=https://www.bloomberg.com/news/articles/2017-10-24/mapping-brooklyn-s-gentrification-via-edison-bulbs |work=Bloomberg News |date=October 24, 2017 |access-date=January 21, 2021 }}</ref> but if uncontrolled bright lights are known to be detrimental to insects, birds, and the view of stars.<ref>{{cite web |url=https://www.darksky.org/light-pollution/ |title=Light Pollution |website=International Dark Sky Association |access-date=January 23, 2021 }}</ref>

== History ==
The history of electric light is well documented,<ref>{{cite podcast |title=Episode 534: The History of Light |url=https://www.npr.org/blogs/money/2014/04/25/306862378/episode-534-the-history-of-light |website=NPR.org |publisher=[[NPR]] |date=April 25, 2014 |access-date=November 11, 2017 }}</ref> and with the developments in lighting technology the profession of lighting developed alongside it.  The development of high-efficiency, low-cost [[fluorescent lamp]]s led to a reliance on electric light and a uniform blanket approach to lighting, but the energy crisis of the 1970s required more design consideration and reinvigorated the use of daylight.<ref>{{cite magazine |url=https://www.architectmagazine.com/technology/lighting/the-energy-crises-of-the-70s_o |title=The Energy Crises of the 70s |first=Elizabeth |last=Donoff |date=December 6, 2016 |magazine=[[Architect Magazine]] |publisher=American Institute of Architects |access-date=January 20, 2021 }}</ref><ref>{{cite web |url=https://americanhistory.si.edu/lightproject/commercial/com_m.htm |date=January 1, 2001 |title=Lighting the Way: Commercial Lighting |website=Smithsonian Institution |access-date=January 20, 2021 }}</ref>

The [[Illuminating Engineering Society of North America]] (IESNA) was formed in 1906 and the UK version was established in 1909 (now known as the Society of Light and Lighting and part of [[Chartered Institution of Building Services Engineers|CIBSE]]).  The [[International Commission on Illumination]] (CIE) was established in 1913 and has become a professional organization accepted as representing the best authority on the subject matter of light and lighting.<ref>{{cite web |url=https://cie.co.at/about-cie |title=About the CIE |date=June 3, 2019 |website=IALD |access-date=January 20, 2021 }}</ref>  The [[Institution of Lighting Professionals]] was established as the Association of Public Lighting Engineers in 1924.  Around the world similar professional organizations evolved.<ref>{{cite web |url=https://cie.co.at/about-cie/links-lighting-organizations |title=Links to Lighting Organizations |website=CIE |access-date=January 20, 2021 }}</ref><ref>{{cite web |url=https://www.lightup.com/learn/lighting-associations-and-other-professional-organizations.html |title=Lighting Associations and Other Professional Organizations |website=LightUp.com |access-date=January 20, 2021 }}</ref>

Initially, these industry organizations were primarily focused on the science and engineering of lighting rather than the aesthetic design,<ref>{{cite web |url=https://www.erco.com/guide/basics/quantitative-lighting-design-2894/en/content-1.php |title=Quantitative Lighting Design |website=ERCO.com |access-date=February 19, 2021 }}</ref> but in 1969 a group of designers established the [[International Association of Lighting Designers]] (IALD).<ref>{{cite web |url=https://www.iald.org/About/About-the-IALD/50th-Anniversary-Year/ |title=50th Anniversary Year |date=June 3, 2019 |website=IALD.org |access-date=February 19, 2021 }}</ref>  Other associations purely for lighting design include the [[Professional Lighting Designers' Association]] (PLDA) established in 1994, the Association de Concepteurs Eclairage (ACE) in France established 1995,<ref>{{cite web |url=https://www.ace-fr.org/ |title=Association de Concepteurs Eclairage |website=ACE |access-date=January 20, 2021 }}</ref> the Associazione Professionisti dell'Illuminazione (APIL) in Italy established in 1998,<ref>{{cite web |url=https://www.apilblog.it/ |title=Associazione Professionisti dell'Illuminazione |website=APIL |access-date=January 20, 2021 }}</ref> the Associação Brasileira de Arquitetos de Iluminação in Brazil in 1999<ref>{{cite web |url=http://www.asbai.org/ |title=Brazilian Association of Lighting Architects |date=January 1, 2019 |website=AsBAI |access-date=January 21, 2021 }}</ref> and the Professional Association of Lighting Designers in Spain (APDI) established in 2008.<ref>{{cite web |url=http://a-pdi.org/ |title=Spanish Association of Professional Lighting Designers |date=January 1, 2012 |website=APDI |access-date=January 20, 2021 }}</ref>

== As a profession ==
<!-- [[Architectural lighting designer]] redirects here. -->
{{See also|Lighting designer}}
[[File:Kimbell Art Museum interior.jpg|thumb|[[Kimbell Art Museum]] interior with daylight control and electric lighting design by [[Richard Kelly (lighting designer)|Richard Kelly]] (1969)]]

'''Architectural lighting designer''' is a stand-alone profession that sits alongside the professions of [[architecture]], [[interior design]], [[landscape architecture]] and [[electrical engineering]].<ref>{{cite web |url=https://www.cld.global/ |title=What Is the CLD? |date=July 1, 2015 |website=CLD |access-date=January 21, 2021 }}</ref>

One of the earliest proponents of architectural lighting design was [[Richard Kelly (lighting designer)|Richard Kelly]] who established his practice in 1935.<ref>{{cite magazine |url=https://www.architectmagazine.com/technology/lighting/richard-kellys-three-tenets-of-lighting-design_o |title=Richard Kelly's Three Tenets of Lighting Design |first=Elizabeth |last=Donoff |date=December 6, 2016 |magazine=Architect Magazine |publisher=American Institute of Architects |access-date=January 19, 2021 }}</ref><ref>{{cite web |url= https://www.erco.com/guide/basics/richard-kelly-2890/en/ |title=Richard Kelly |website=ERCO |access-date=January 20, 2021 }}</ref>  Kelly developed an approach to architectural lighting that is still used today, based on the perception of three visual elements as presented in a 1952 joint meeting of The [[American Institute of Architects]], the American Society of Industrial Designers (now the [[Industrial Designers Society of America]]), and the Illuminating Engineering Society of North America, in [[Cleveland]].<ref>{{cite journal |last=Kelly |first=Richard |title=Lighting as an Integral Part of Architecture |url=http://www.mpcfaculty.net/mary_nelson/facs/coursework/intd52/assignments/Richard%20Kelly--Lighting%20as%20an%20Integral%20Part%20of%20Architecture.pdf |journal=College Art Journal |volume=12 |issue=1 |pages=24–30 |doi=10.2307/773361 |date=Autumn 1952 |jstor=773361 |s2cid=108429973 |access-date=January 29, 2021 }}</ref>

=== Education ===
While many architectural lighting designers have a background in electrical engineering, [[architectural engineering]], architecture, or [[luminaire]] manufacturing, several universities and technical schools now offer degree programs specifically in architectural lighting design.<ref>{{cite web |title=Learn2Light |url=https://www.iald.org/IALD-Education-Trust/STUDENTS/learn-2-light/Lighting-Design-Schools |website=IALD.com |publisher=International Association of Lighting Designers |access-date=January 26, 2021 }}</ref><ref>{{cite web |title= Lighting Courses |url=https://www.cibse.org/society-of-light-and-lighting-sll/education/lighting-courses |website=CIBSE.org |publisher=Society of Light and Lighting |access-date=January 29, 2021 }}</ref>

=== Process ===
The process of architectural lighting design generally follows the architect's plan of works in terms of key project stages: feasibility, concept, detail, construction documentation, site supervision and commissioning.<ref>{{cite web |url=https://www.architecture.com/knowledge-and-resources/resources-landing-page/riba-plan-of-work |date=February 28, 2020 |title=RIBA Plan of Work |website=Architecture.com |publisher=Royal Institute of British Architects |access-date=September 27, 2022 }}</ref><ref>{{cite web |url=https://www.nultylighting.co.uk/about/ |date=2020 |title=About |at=Process |website=NultyLighting.co.uk |access-date=September 27, 2022 }}</ref>

After the feasibility stage, where the parameters for the project are set, the concept stage is when the lighting design is developed in terms of lit effect, technical lighting targets and overall visual strategy usually using concept sketches, [[Architectural rendering|renderings]], or [[mood board]]s.{{Citation needed|date=January 2021}}

== Day lighting ==
The source for daylight or natural lighting is the sun.<ref name="Kilmer-2014" /> Sunlight provides the greatest quality of light, rated 100, on the [[electromagnetic spectrum]]. There are psychological and physical health benefits that come from using daylight in a space. For example, it can help to ease [[seasonal affective disorder]] (SAD), it can provide people with the necessary [[vitamin D]], and can assist in regulating [[circadian rhythm]]s, or daily light and dark cycles. Using daylight as a light source can eliminate the use of [[energy]]. Daylighting can also cause deterioration of materials and finishes and an increased use of energy for cooling a space. The architectural makeup of a space impacts the day lighting. It can be used in a space through windows, openings of the interior, [[skylight]]s, and reflective surfaces.<ref name="Karlen 2017" />

== Electric lighting ==
Electric lighting or artificial lighting is a type of architectural lighting that includes [[electric light sources]]. The overall purpose of electric lighting is to allow the user of the space to see at various times in the day, but especially at night, when daylight is no longer a possible source of light. Artificial lighting helps to create or enhance the aesthetic of a space. Various techniques can be implemented when it comes to electric lighting, since users have more control over the light. This can include dimming or increasing the brightness of a lamp, diffusion of the light source, and the use of different lamp hues. The main sources used for electric lighting include [[incandescent lamps]], [[Solid-state lamp|solid state lamps]], and [[Gas-discharge lamp|gas discharge lamps]].<ref name="Kilmer-2014">{{Cite book |last=Kilmer |first=Rosemary |url=https://www.worldcat.org/oclc/845085518 |title=Designing interiors |date=2014 |others=W. Otie Kilmer |isbn=978-1-118-02464-5 |edition=2nd |location=Hoboken, New Jersey |oclc=845085518}}</ref>

== Fixtures ==
{{Main|Light fixture}}
[[File:PH-Lampan 1.jpg|thumb|The [[PH-lamp|PH5 lamp]], designed in 1958]]

Lighting fixtures come in a wide variety of styles for various functions. The most important functions are as a holder for the light source, to provide directed light and to avoid [[visual glare]]. Some are very plain and functional, while some are pieces of art in themselves. Nearly any material can be used, so long as it can tolerate the excess heat and is in keeping with safety codes.

An important property of light fixtures is the [[luminous efficacy]] or [[wall-plug efficiency]], meaning the amount of usable light emanating from the fixture per used energy, usually measured in [[Lumen (unit)|lumen]] per [[watt]]. A fixture using replaceable light sources can also have its efficiency quoted as the percentage of light passed from the "bulb" to the surroundings. The more [[Transparency and translucency|transparent]] the lighting fixture is, the higher efficacy. Shading the light will normally decrease efficiency but increase the directionality and the [[visual comfort probability]].

The [[PH-lamp]]s are a series of light fixtures designed by Danish designer and writer [[Poul Henningsen]] from 1926 onwards.<ref>{{cite web |title=The PH lamp |url=http://www.visitdenmark.com/uk/en-gb/menu/turist/inspiration/detkulturelledanmark/design/the-ph-lamp.htm |website=Visit Denmark |archive-url=https://web.archive.org/web/20120215054112/http://www.visitdenmark.com/uk/en-gb/menu/turist/inspiration/detkulturelledanmark/design/the-ph-lamp.htm |archive-date=February 15, 2012 }}.</ref> The lamp is designed with multiple concentric shades to eliminate visual glare, only emitting reflected light, obscuring the light source.<ref>{{cite web |title=Poul Henningsen |url=http://www.louispoulsen.com/en/Designers/Poul%20Henningsen.aspx |publisher=Louis Poulsen Lighting |archive-url=https://web.archive.org/web/20131118201306/http://www.louispoulsen.com/en/Designers/Poul%20Henningsen.aspx |archive-date=November 18, 2013 }}</ref>

== Lighting design layers ==
Designers utilize the idea of lighting layers when creating a lighting plan for a space. Lighting layers include: task layer, focal layer, ambient layer, decorative layer, and daylight layer. Each layer contributes a function to the space and often they work together to create a well composed lighting design. The task layer is lighting that serves a purpose to perform a certain job or task. Typically, in this layer, there tends to be a need for more light. An example of this would be the use of under cabinet lighting in a kitchen. The focal layer is when lighting is used to highlight a certain feature in a room, such as a fireplace. This type of lighting draws the eye to that certain area. The [[available light|ambient layer]] provides for background or general lighting. This layer has a strong influence on the brightness of a space. In the decorative layer, lighting is used as an ornament to the space and can help develop the style. The daylight layer uses [[Daylighting (architecture)|natural light]] or the sun to light a space. Using the layering technique helps to develop the aesthetic and functionality of lighting.<ref name="Karlen 2017" />

== Photometric studies ==
<!-- "Photometric study" redirects here. -->
[[File:PlanckianLocus.png|thumb|The [[CIE 1931]] ''x,y'' chromaticity space, also showing the chromaticities of black-body light sources of various temperatures ([[Planckian locus]]), and lines of constant ''[[#Correlated color temperature|correlated color temperature]]'']]

'''Photometric studies''' are performed to simulate lighting designs for projects before they are built or renovated.  This enables [[architect]]s, lighting designers, and [[engineer]]s to determine whether a proposed lighting layout will deliver the amount of light intended.<ref>{{cite web |title=Photometric Study – What Is a Light Study and When Do I Need It |url=https://www.ledlightexpert.com/Photometric-Study--What-is-a-light-study-and-When-do-I-need-it_ep_53-1.html |website=LEDLightExpert.com |access-date=January 22, 2021 }}</ref> They will also be able to determine the contrast ratio between light and dark areas. In many cases these studies are referenced against IESNA or CIBSE recommended lighting practices for the type of application.  Depending on the type of area, different design aspects may be emphasized for safety or practicality (i.e. such as maintaining uniform light levels, avoiding glare or highlighting certain areas).  A specialized [[List of lighting design applications|lighting design application]] is often used to create these, which typically combine the use of two-dimensional digital [[Computer-aided design|CAD]] drawings and lighting [[simulation software]].

[[Color temperature]] for white light sources also affects their use for certain applications. The color temperature of a white light source is the temperature in [[kelvin]] of a theoretical [[black body]] emitter that most closely matches the spectral characteristics of the lamp. [[Incandescent light bulb]]s have a color temperature around 2700 to 3000 kelvin; daylight is around 6400 kelvin. Lower color temperature lamps have relatively more energy in the yellow and red part of the visible spectrum, while high color temperatures correspond to lamps with more of a blue-white appearance.  For critical inspection or color matching tasks, or for retail displays of food and clothing, the color temperature of the lamps will be selected for the best overall lighting effect.  Color may also be used for functional reasons.  For example, blue light makes it difficult to see veins and thus may be used to discourage drug use.<ref>{{cite web |last=Watts |first=Amanda |title=Gas Station Installs Blue Lights to Combat Drug Use |url=http://www.cnn.com/2017/12/07/health/bathroom-blue-lights-trnd/index.html |work=[[CNN]] |date=December 7, 2017 |access-date=January 16, 2018 }}</ref>

== Correlated color temperature ==
{| class="wikitable floatright" <!-- hexadecimal values of background colors of the cells from http://www.vendian.org/mncharity/dir3/blackbody/UnstableURLs/bbr_color.html -->
|-
! Temperature
! Source
|-
| bgcolor="#ff7900" | 1,700&nbsp;K
| Match flame, low-pressure sodium lamps (LPS/SOX)
|-
| bgcolor="#ff7e00" | 1,850&nbsp;K
| Candle flame, sunrise, sunset
|-
| bgcolor="#ffb46b" | 2,700–3,300&nbsp;K
| Incandescent lamps, soft-white fluorescent lamps
|-
| bgcolor="#ffb46b" | 3,000&nbsp;K
| Warm-white fluorescent lamps
|-
| bgcolor="#ffd3a8" | 4,100–4,150&nbsp;K
| Moonlight,<ref>{{cite web |url=http://www.cast-lighting.com/search/1/display-document/71 |archive-url=https://archive.today/20120730050158/http://www.cast-lighting.com/search/1/display-document/71 |title=Moonlighting: Landscape Lighting Design Imitates Nature |last=Parrott |first=Steve |archive-date=July 30, 2012 |access-date=November 25, 2021 }}</ref> cool-white fluorescent lamps
|-
| bgcolor="#ffe4ce" | 5,000&nbsp;K
| Horizon daylight
|-
| bgcolor="#ffefe6" | 5,500–6,000&nbsp;K
| Vertical daylight, electronic flash
|-
| bgcolor="#fff5f5" | 6,200&nbsp;K
| [[Xenon arc lamp|Xenon short-arc lamp]]<ref name="OSI">{{cite web |url=http://assets.sylvania.com/assets/documents/ENGR_BLTN11.161355cc-1d94-4996-b6cd-a3001fea6f1a.pdf |title=Osram Sylvania XBO |archive-url=https://web.archive.org/web/20160303212115/http://assets.sylvania.com/assets/documents/ENGR_BLTN11.161355cc-1d94-4996-b6cd-a3001fea6f1a.pdf |archive-date=March 3, 2016 }}</ref>
|-
| bgcolor="#fff9fd" | 6,500&nbsp;K
| Daylight, overcast, daylight fluorescent lamps
|-
| bgcolor="#e4eaff" | 6,500–10,500&nbsp;K
| LCD or CRT screen
|-
| bgcolor="#a8c5ff" | 15,000–27,000&nbsp;K
| Clear blue poleward sky
|-
| colspan="2" | These temperatures are merely characteristic;<br>considerable variation may be present.
|}

The [[correlated color temperature]] (CCT) of a light source is the [[temperature]] of an ideal black-body radiator that radiates light of comparable [[hue]] to that of the light source. Color temperature is a characteristic of [[visible light]] that has important applications in [[lighting]], [[photography]], [[videography]], [[publishing]], [[manufacturing]], [[astrophysics]], [[horticulture]], and other fields. In practice, color temperature is only meaningful for light sources that do in fact correspond somewhat closely to the radiation of some black body (i.e. those on a line from red-orange via yellow and more or less white to blueish white); it does not make sense to speak of the color temperature of (e.g. a green or a purple light). Color temperature is conventionally stated in the unit of absolute temperature, the kelvin, having the unit symbol K.

For lighting building interiors, it is often important to take into account the color temperature of illumination. For example, a warmer (i.e. lower color temperature) light is often used in public areas to promote relaxation, while a cooler (higher color temperature) light is used to enhance concentration in offices.<ref>{{cite book |title=Encyclopedia of Laser Physics and Technology |last=Paschotta |first=Rüdiger |publisher=[[Wiley-VCH]] |date=2008 |isbn=978-3-527-40828-3 |page=219 |url=https://books.google.com/books?id=BN026ye2fJAC&q=lighting%20color-temperature%20relaxing&pg=PA219 }}{{Dead link|date=September 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

CCT dimming for LED technology is regarded as a difficult task, since binning, age and temperature drift effects of LEDs change the actual color value output. Here feedback loop systems are used for example with color sensors, to actively monitor and control the color output of multiple color mixing LEDs.<ref>{{cite book |title=Sensors and Feedback Control of Multi-Color LED Systems |first1=Thomas |last1=Nimz |first2=Fredrik |last2=Hailer |first3=Kevin |last3=Jensen |publisher=LED Professional |date=2012 |issn=1993-890X |pages=2–5 |url=http://www.mazet.de/en/english-documents/english/featured-articles/sensors-and-feedback-control-of-multi-color-led-systems-1/download#.UX7VXYIcUZI |archive-url=https://web.archive.org/web/20140429162806/http://www.mazet.de/en/english-documents/english/featured-articles/sensors-and-feedback-control-of-multi-color-led-systems-1/download#.UX7VXYIcUZI |archive-date=April 29, 2014 |access-date=March 14, 2015 }}</ref>

The color temperature of the [[electromagnetic radiation]] emitted from an ideal black body is defined as its surface temperature in Kelvin, or alternatively in ''[[mired]]s'' (micro-reciprocal kelvin).<ref>{{cite book |last=Stevens |first=Wallace Roberts |title=Principles of Lighting |publisher=Constable |date=1951 |url=https://books.google.com/books?id=gH5RAAAAMAAJ&q=micro-reciprocal-degree+date:0-1960 }}</ref> This permits the definition of a standard by which light sources are compared.

== Methods ==
For simple installations, hand-calculations based on tabular data can be used to provide an acceptable lighting design. More critical or optimized designs now routinely use mathematical modeling on a computer.

Based on the positions and mounting heights of the fixtures, and their photometric characteristics, the proposed lighting layout can be checked for uniformity and quantity of illumination. For larger projects or those with irregular floor plans, lighting design software can be used. Each fixture has its location entered, and the reflectance of walls, ceiling, and floors can be entered. The computer program will then produce a set of contour charts overlaid on the project floor plan, showing the light level to be expected at the working height. More advanced programs can include the effect of light from windows or skylights, allowing further optimization of the operating cost of the lighting installation. The amount of daylight received in an internal space can typically be analyzed by undertaking a [[daylight factor]] calculation.

The Zonal Cavity Method is used as a basis for both hand, tabulated, and computer calculations. This method uses the reflectance coefficients of room surfaces to model the contribution to useful illumination at the working level of the room due to light reflected from the walls and the ceiling. Simplified photometric values are usually given by fixture manufacturers for use in this method.

Computer modeling of outdoor flood lighting usually proceeds directly from photometric data. The total lighting power of a lamp is divided into small solid angular regions. Each region is extended to the surface which is to be lit and the area calculated, giving the light power per unit of area. Where multiple lamps are used to illuminate the same area, each one's contribution is summed. Again the tabulated light levels (in lux or foot-candles) can be presented as contour lines of constant lighting value, overlaid on the project plan drawing. Hand calculations might only be required at a few points, but computer calculations allow a better estimate of the uniformity and lighting level.

== Design-media terminology ==
; Adjustable accent fixture : Used to point at certain design elements<ref name="Karlen 2017" />
; [[Bollard]] : A type of architectural outdoor lighting that is a short, upright ground-mounted unit typically used to provide cutoff type illumination for egress lighting, to light walkways, steps, or other pathways<ref name="Karlen 2017" />
; "Cans" with a variety of lamps : Jargon for inexpensive [[downlighting]] products that are recessed into the ceiling, or sometimes for uplights placed on the floor. The name comes from the shape of the housing.  The term "pot lights" is often used in Canada and parts of the US.{{Citation needed|date=March 2023}}
; [[Chandelier]] : A branched ornamental [[light fixture]] designed to be mounted on ceilings<ref>{{cite web |url=https://krmlight.com/chandeliers-for-lower-ceilings/ |title=Chandeliers for Lower Ceilings |website=KRM Light |date=January 6, 2020 |access-date=October 29, 2020 }}</ref> or walls<ref>{{cite encyclopedia |title=Chandelier |url=http://dictionary.reference.com/browse/chandelier |dictionary=Dictionary.com |access-date=May 2, 2014 }}</ref>
; [[Cove light]] : Recessed into the ceiling in a long box against a wall<ref name="Karlen 2017" />
; [[Emergency lighting]] or [[exit sign]] : Connected to a [[battery backup]] or to an electric circuit that has [[Emergency power system|emergency power]] if the [[mains power]] fails{{Citation needed|date=March 2023}}
; [[Flood lighting]] : Usually [[Utility pole|pole]]- or [[stanchion]]-mounted; for landscape, roadways, and parking lots<ref>{{Cite web |title=floodlight (exterior lighting) – Illuminating Engineering Society |url=https://www.ies.org/definitions/floodlight-exterior-lighting/ |access-date=May 26, 2020 }}</ref>
; High- and low-bay lighting : Typically used for general lighting for industrial buildings and often [[big-box store]]s{{Citation needed|date=March 2023}}
; [[Lightbulb|Lamp]] : Lightbulb, comes in various shapes and sizes<ref name="Karlen 2017" />
; [[Luminaire]] : Holds and supports lamp, provides electrification<ref name="Karlen 2017" />
; [[Outdoor lighting]] and [[landscape lighting]] : Used to illuminate walkways, [[parking lot]]s, [[roadway]]s, building exteriors and architectural details, [[garden]]s, and [[park]]s{{Citation needed|date=March 2023}}
; [[Pendant light]] : Suspended from the ceiling with a chain or pipe<ref>{{Cite web|url=https://www.ies.org/definitions/suspended-pendant-luminaire/|title=suspended (pendant) luminaire – Illuminating Engineering Society|access-date=March 27, 2020 }}</ref>
; [[Recessed light]] : The protective housing is concealed behind a ceiling or wall, leaving only the fixture itself exposed. The ceiling-mounted version is often called a downlight<ref name="Karlen 2017" />
; [[Sconce (light fixture)|Sconce]] : A decorative light fixture that is mounted to a wall<ref>{{cite web |url=https://www.archtoolbox.com/materials-systems/electrical/lightfixtures.html |title=Light Fixture (Luminaire) Types |website=ArchToolbox.com |access-date=February 8, 2023 |archive-url=https://web.archive.org/web/20171026184604/https://www.archtoolbox.com/materials-systems/electrical/lightfixtures.html |archive-date=October 26, 2017 }}</ref>
; [[Street light]] : A type of outdoor pole-mounted light used to light streets and roadways; similar to pole-mounted flood lights but with a type II lens (side to side light distribution pattern) instead of type III<ref>{{Cite web |url=https://www.energy.gov/sites/prod/files/2017/10/f37/postings_10-11-17.pdf |title=A Look at Outdoor Area Lighting |date=October 11, 2017 |website=US Department of Energy }}</ref>
; Strip lights or industrial lighting : Often long lines of fluorescent lamps used in a [[warehouse]] or [[factory]]{{Citation needed|date=March 2023}}
; [[Surface mount|Surface-mounted]] light : The finished housing is exposed, not flush mount with surface.{{Citation needed|date=March 2023}}
; [[Track lighting]] fixture : Individual fixtures (called ''track heads'') can be positioned anywhere along the track, which provides electric power<ref name="Karlen 2017" />
; Under-cabinet light : Mounted below kitchen wall cabinets{{Citation needed|date=March 2023}}
; [[Troffer]] : Recessed fluorescent light fixtures, usually rectangular in shape to fit into a drop ceiling grid<ref>{{cite web |url=https://www.ies.org/definitions/troffer/ |title=troffer |publisher=Illuminating Engineering Society |access-date=March 27, 2020 }}</ref>
; Wall grazing fixture : Light is closely placed to wall, typically to enhance a textured surface.<ref name="Karlen 2017" />
; [[Wallwasher]] : An asymmetric light fixture that lights from ceiling to floor and flatly illuminates the wall<ref name="Karlen 2017" />

== Lamp types ==
Different types of [[Electricity|electric]] lighting have vastly differing efficacy and color temperature:<ref>{{cite web |title=Memorandum from Martin T Brown |url=http://www.parliament.the-stationery-office.co.uk/pa/cm200203/cmselect/cmsctech/747/747we81.htm |archive-url=https://web.archive.org/web/20160303170830/http://www.parliament.the-stationery-office.co.uk/pa/cm200203/cmselect/cmsctech/747/747we81.htm |website=Parliament.The-Stationery-Office.co.uk |date=October 6, 2003 |archive-date=March 3, 2016 |access-date=January 22, 2021 }}</ref>

{| class="wikitable"
|-
! Name !! [[Optical spectrum]] !! [[Luminous efficacy]]<br>([[Lumen (unit)|lm]]/[[watt|W]]) !! Lifetime ([[MTTF]])<br>(hours) !! [[Color temperature]]<br>([[kelvin]]) !! [[Color]] appearance !! [[Color rendering index|Color<br>rendering<br>index]]
|-
| [[Incandescent light bulb]] || [[Continuous spectrum|Continuous]] || 4–17 || 2–20000 || 2400–3400 || Warm white (yellowish) || 100
|-
| [[Halogen lamp]] || Continuous || 16–23 || 3000–6000 || 3200 || Warm white (yellowish) || 100
|-
| Fluorescent lamp || [[Mercury (element)|Mercury]] line + [[Phosphor]] || 52–100 (white) || 8000–20000 || 2700–5000<sup>*</sup> || White (various color temperatures), as well as saturated colors available || 15-85
|-
| [[Metal halide lamp]] || Quasi-continuous || 50–115 || 6000–20000 || 3000–4500 || Cold white || 65–93
|-
| [[Sulfur lamp]] || Continuous || 80–110 || 15000–20000 || 6000 || Pale green || 79
|-
| [[High-pressure sodium]] || Broadband || 55–140 || 10000–40000 || 1800–2200<sup>*</sup> || Pinkish orange || 0–70
|-
| [[Low-pressure sodium]] || Narrow line || 100–200 || 18000–20000 || 1800<sup>*</sup> || Yellow, no color rendering || 0
|-
| [[Light-emitting diode]] (white){{Failed verification|date=January 2021}} || Line plus phosphor || 10–200 || 50,000–100,000 || Various white from 2700 to 6000<sup>*</sup> || Various color temperatures, as well as saturated colors || 70–85 (white)
|-
| Induction lamp{{Failed verification|date=January 2021}} || Mercury line + Phosphor || 70–90 || 80,000–100,000 || Various white from 2700 to 6000<sup>*</sup> || Various color temperatures, as well as saturated colors || 70–85 (white)
|}
<sup>*</sup><small>Color temperature is defined as the temperature of a black body emitting a similar spectrum; these spectra are quite different from those of black bodies.</small>

The most [[Energy conservation|efficient]] source of electric light is the low-pressure sodium lamp. It produces, for all practical purposes, a [[monochromatic]] yellow light, which gives a similarly monochromatic perception of any illuminated scene. For this reason, it is generally reserved for outdoor public lighting usages. Low-pressure sodium lights are favored for public lighting by astronomers, since the [[light pollution]] that they generate can be easily filtered, contrary to broadband or continuous spectra.

=== Incandescent light bulb ===
{{Main|Incandescent light bulb}}

The modern incandescent light bulb, with a coiled filament of tungsten, was commercialized in the 1920s developed from the carbon [[Electrical filament|filament]] lamp introduced in about 1880. As well as bulbs for normal illumination, there is a very wide range, including low voltage, low-power types often used as components in equipment, but now largely displaced by LEDs.{{citation needed|date=January 2021}}

=== Fluorescent lamp ===
{{Main|Fluorescent lamp}}

Fluorescent lamps consist of a glass tube that contains mercury vapor or argon under low pressure. Electricity flowing through the tube causes the gases to give off ultraviolet energy. The inside of the tubes are coated with [[phosphor]]s that give off visible light when struck by ultraviolet energy.<ref>{{cite book |last1=Perkowitz |first1=Sidney |last2=Henry |first2=A. Joseph |date=November 23, 1998 |title=Empire of Light: A History of Discovery in Science and Art |url=https://archive.org/details/empireoflighthis00perk_0|url-access=registration |quote=fluorescent lights mercury vapor excites. |publisher=Joseph Henry Press |isbn=978-0309065566 |access-date=November 4, 2014 }}</ref>

=== LED lamp ===
{{Main|LED lamp}}

[[Light-emitting diodes]] (LEDs) became widespread as indicator lights in the 1970s. With the invention of high-output LEDs by [[Shuji Nakamura]], LEDs are now in use as [[solid-state lighting]] for general lighting applications.<ref>{{cite web |title=The Nobel Prize in Physics 2014 |url=https://www.nobelprize.org/prizes/physics/2014/nakamura/facts/ |website=NobelPrize.org |publisher=[[Nobel Prize|Nobel Prize Outreach]] |date=2014 |access-date=November 25, 2021 }}</ref>

Initially, due to relatively high cost per lumen, LED lighting was most used for lamp assemblies of under 10&nbsp;W such as [[flashlight]]s. Development of [[LED lamp|higher-output lamps]] was motivated by programs such as the U.S. [[L Prize]].<ref>{{Cite web |title=L Prize Competition |url=https://www.energy.gov/eere/ssl/l-prize-competition |website=Energy.gov |access-date=May 26, 2020 }}</ref>

== See also ==

* {{annotated link|Architectural glass}}
* {{annotated link|Architectural light shelf}}
* {{annotated link|Architecture of the night}}
* {{annotated link|Daylight harvesting}}
* {{annotated link|Deck prism}}
* {{annotated link|Light art}}
* {{annotated link|Light + Building}}
* {{annotated link|Light tube}}
* {{annotated link|Lighting control system}}
* {{annotated link|Lighting for the elderly}}
* {{annotated link|Lumen method}}
* {{annotated link|Over illumination}}
* {{annotated link|Passive solar building design}}
* {{annotated link|Professional Lighting and Sound Association}}
* {{annotated link|Smart glass}}
* {{annotated link|Stage lighting}}
* {{annotated link|Sun path}}
* {{annotated link|Sustainable lighting}}
* {{annotated link|Transom (architectural)}}
* {{annotated link|Vivid Sydney}}

== References ==
{{Reflist}}

== External links ==
* [http://www.schorsch.com/kbase/glossary/ Lighting design glossary]

{{Artificial light sources}}
{{Design}}

[[Category:Architectural lighting design| ]]
[[Category:Garden features]]

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