Editing Daylighting (architecture) (section)

===Windows===
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{{Main|Window}}

Windows are the most common way to admit daylight into a space. Their vertical orientation means that they selectively admit sunlight and diffuse daylight at different times of the day and year. Therefore, windows on multiple orientations must usually be combined to produce the right mix of light for the building, depending on the climate and latitude. There are three ways to improve the amount of light available from a window:<ref name="Building for Energy Independence: Sun/Earth Buffering and Superinsulation">{{cite book |date= 1983 |title= Building for Energy Independence: Sun/Earth Buffering and Superinsulation |publisher= Community Builders |isbn= 978-0960442249 |url-access= registration |url= https://archive.org/details/buildingforenerg0000boot }}</ref> (a) placing the window close to a light colored wall, (b) slanting the sides of window openings so the inner opening is larger than the outer opening, or (c) using a large light colored window-sill to project light into the room. Besides permitting daylighting into the building, windows serve another function in daylighting practice, providing views out.<ref>{{cite journal |last1= Kent |first1= Michael |last2= Schiavon |first2= Stefano |date= 2020 |title= Evaluation of the effect of landscape distance seen in window views on visual satisfaction | url= https://escholarship.org/content/qt6gd9t8pj/qt6gd9t8pj.pdf?t=qf0euu |journal= Building and Environment | volume= 183 |  pages= 107160 | doi= 10.1016/j.buildenv.2020.107160 |bibcode= 2020BuEnv.18307160K |s2cid= 221935768 | access-date= 2021-08-11}}</ref> To enhance the quality of the view seen from a window, three primary variables need to be ensure: view content (what can be seen in the view), view access (how much of the window view can be seen), and view clarity (how clearly the view can be seen).<ref>{{cite journal |last1= Ko |first1= Won Hee |last2= Kent|first2= Michael | last3= Schiavon | first3= Stefano | last4= Levitt | first4= Brendon | last5= Betti | first5= Giovanni | date= 2021 |title= A Window View Quality Assessment Framework | url= https://www.tandfonline.com/doi/full/10.1080/15502724.2021.1965889?scroll=top&needAccess=true |journal= LEUKOS |volume= 18 |issue= 3 |pages= 268–293 | doi= 10.1080/15502724.2021.1965889 |arxiv= 2010.07025 |s2cid= 222341349 | access-date= 2021-11-30}}</ref> View clarity is often influenced by the amount of shading provided by blinds or devices used to protect occupants from harsh daylight (e.g. [[Glare (vision)|glare]]) or for reasons of [[visual privacy]]. Environmental criteria serve as important criteria to gauge the quality of window view content.<ref>{{cite journal |last1= Kent |first1= Michael |last2= Schiavon|first2= Stefano | date= 2022 |title= Predicting Window View Preferences Using the Environmental Information Criteria | url= https://escholarship.org/content/qt7rv6936v/qt7rv6936v.pdf?t=rgtbft |journal= LEUKOS |volume= 19 |issue= 2 |pages= 190–209 | doi=10.1080/15502724.2022.2077753 |s2cid= 251121476 | access-date= 2022-11-09}}</ref> These criteria can be distilled into five important factors, namely: Location, time, weather, people, and nature. Notably, views that are able to provide building inhabitants with content of [[nature]] far outweigh the other four Environmental Information Criteria.

Different types and grades of [[glass]] and different window treatments can also affect the amount of light transmission through the windows. The type of [[Glazing (window)|glazing]] is an important issue, expressed by its VT coefficient (Visual Transmittance),<ref>{{cite web|url = http://www.nfrc.org/energy-performance-label/|title = Energy Performance Label|website = The National Fenestration Rating Council|date = 20 July 2016|access-date = 4 March 2019}}</ref> also known as visual light transmittance (VLT). As the name suggests, this coefficient measures how much visible light is admitted by the window. A low VT (below 0.4) can reduce by half or more the light coming into a room. But be also aware of high VT glass: high VT numbers (say, above 0.60) can be a cause of glare. On the other hand, you should also take into account the undesirable effects of large windows.

Windows grade into translucent walls (below).

====Clerestory windows====
Another important element in creating daylighting is the use of [[clerestory]] windows. These are high, vertically placed windows. They can be used to increase direct solar gain when oriented towards the equator. When facing toward the sun, clerestories and other windows may admit unacceptable [[Glare (vision)|glare]]. In the case of a [[passive solar]] house, clerestories may provide a direct light path to polar-side (north in the northern hemisphere; south in the southern hemisphere) rooms that otherwise would not be illuminated. Alternatively, clerestories can be used to admit diffuse daylight (from the north in the northern hemisphere) that evenly illuminates a space such as a classroom or office.

Often, clerestory windows also shine onto interior wall surfaces painted white or another light color. These walls are placed so as to reflect indirect light to interior areas where it is needed. This method has the advantage of reducing the directionality of light to make it softer and more diffuse, reducing shadows.

====Sawtooth roof====
Another roof-angled glass alternative is a [[saw-tooth roof|sawtooth roof]] (found on older factories). Sawtooth roofs have vertical roof glass facing away from the equator side of the building to capture diffused light (not harsh direct equator-side solar gain).<ref name="LG10">{{cite book |date=1999|title= CIBSE Lighting Guide 10: Daylighting and window design |publisher= CIBSE |isbn= 978-0-900953-98-9}}</ref> The angled portion of the glass-support structure is opaque and well insulated with a cool roof and [[radiant barrier]]. The sawtooth roof's lighting concept partially reduces the summer "solar furnace" skylight problem, but still allows warm interior air to rise and touch the exterior roof glass in the cold winter, with significant undesirable heat transfer.<ref>{{cite journal | first = F. | last = Asdrubali | year = 2003 | title = Lighting Research and Technology: "Daylighting performance of sawtooth roofs of industrial buildings "| journal=Lighting Research and Technology | volume = 35 | issue = 4| pages = 343–359 | doi = 10.1191/1365782803li094oa| s2cid = 109902823 }}</ref>