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A window is an
opening Opening may refer to: * Al-Fatiha, "The Opening", the first chapter of the Qur'an * The Opening (album), live album by Mal Waldron * Backgammon opening * Chess opening * A title sequence or opening credits * , a term from contract bridge * , ...
in a
wall A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or, is decorative. There are many kinds of walls, including: * Walls in buildings that form a fundamental part of the supe ...
,
door A door is a hinged or otherwise movable barrier that allows ingress (entry) into and egress (exit) from an enclosure. The created opening in the wall is a ''doorway'' or ''portal''. A door's essential and primary purpose is to provide security b ...
,
roof A roof ( : roofs or rooves) is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of temper ...
, or
vehicle A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), wa ...
that allows the exchange of
light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...
and may also allow the passage of sound and sometimes
air The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for ...
. Modern windows are usually glazed or covered in some other
transparent Transparency, transparence or transparent most often refer to: * Transparency (optics), the physical property of allowing the transmission of light through a material They may also refer to: Literal uses * Transparency (photography), a still, ...
or translucent
material Material is a substance or mixture of substances that constitutes an object. Materials can be pure or impure, living or non-living matter. Materials can be classified on the basis of their physical and chemical properties, or on their geologi ...
, a
sash A sash is a large and usually colorful ribbon or band of material worn around the body, either draping from one shoulder to the opposing hip and back up, or else running around the waist. The sash around the waist may be worn in daily attire, bu ...
set in a frame in the opening; the sash and frame are also referred to as a window. Many glazed windows may be opened, to allow
ventilation Ventilation may refer to: * Ventilation (physiology), the movement of air between the environment and the lungs via inhalation and exhalation ** Mechanical ventilation, in medicine, using artificial methods to assist breathing *** Ventilator, a ma ...
, or closed, to exclude
inclement weather Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmosphere, the tr ...
. Windows may have a
latch A latch or catch (called sneck in Northern England and Scotland) is a type of mechanical fastener that joins two (or more) objects or surfaces while allowing for their regular separation. A latch typically engages another piece of hardware on t ...
or similar
mechanism Mechanism may refer to: *Mechanism (engineering), rigid bodies connected by joints in order to accomplish a desired force and/or motion transmission *Mechanism (biology), explaining how a feature is created *Mechanism (philosophy), a theory that a ...
to
lock Lock(s) may refer to: Common meanings *Lock and key, a mechanical device used to secure items of importance *Lock (water navigation), a device for boats to transit between different levels of water, as in a canal Arts and entertainment * ''Lock ...
the window shut or to hold it open by various amounts. In addition to this, many modern day windows may have a
window screen A window screen (also known as insect screen, bug screen, fly screen, flywire, wire mesh, or window net) is designed to cover the opening of a window. It is usually a mesh made of metal, fiberglass, fibreglass, plastic wire, or other pieces of ...
or mesh, often made of
aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...
or
fibreglass Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clo ...
, to keep bugs out when the window is opened. Types include the eyebrow window, fixed windows,
hexagonal window A hexagonal window (also Melnikov's or honeycomb window) is a hexagon-shaped window, resembling a bee cell or crystal lattice of graphite. The window can be vertically or horizontally oriented, openable or fixed. It can also be regular or elongately ...
s, single-hung, and double-hung sash windows, horizontal sliding
sash window A sash window or hung sash window is made of one or more movable panels, or "sashes". The individual sashes are traditionally paned window (architecture), paned windows, but can now contain an individual sheet (or sheets, in the case of double gla ...
s,
casement window A casement window is a window that is attached to its frame by one or more hinges at the side. They are used singly or in pairs within a common frame, in which case they are hinged on the outside. Casement windows are often held open using a cas ...
s, awning windows, hopper windows, tilt, and slide windows (often door-sized), tilt and turn windows, transom windows, sidelight windows, jalousie or
louver A louver (American English) or louvre (British English British English (BrE, en-GB, or BE) is, according to Lexico, Oxford Dictionaries, "English language, English as used in Great Britain, as distinct from that used elsewhere". Mor ...
ed windows,
clerestory In architecture, a clerestory ( ; , also clearstory, clearstorey, or overstorey) is a high section of wall that contains windows above eye level. Its purpose is to admit light, fresh air, or both. Historically, ''clerestory'' denoted an upper l ...
windows,
lancet window A lancet window is a tall, narrow window with a pointed arch at its top. It acquired the "lancet" name from its resemblance to a lance. Instances of this architectural element are typical of Gothic church edifices of the earliest period. Lancet wi ...
s,
skylights A skylight (sometimes called a rooflight) 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. History Open ...
,
roof window A roof window is an outward opening window that is incorporated as part of the design of a roof. Often confused with a skylight, a roof window differs in a few basic ways. A roof window is often a good option when there is a desire to allow both ...
s,
roof lantern A roof lantern is a daylighting architectural element. Architectural lanterns are part of a larger roof and provide natural light into the space or room below. In contemporary use it is an architectural skylight structure. A lantern roof wil ...
s,
bay window A bay window is a window space projecting outward from the main walls of a building and forming a bay in a room. Types Bay window is a generic term for all protruding window constructions, regardless of whether they are curved or angular, or r ...
s,
oriel window An oriel window is a form of bay window which protrudes from the main wall of a building but does not reach to the ground. Supported by corbels, bracket (architecture), brackets, or similar cantilevers, an oriel window is most commonly found pro ...
s, thermal, or
Diocletian Diocletian (; la, Gaius Aurelius Valerius Diocletianus, grc, Διοκλητιανός, Diokletianós; c. 242/245 – 311/312), nicknamed ''Iovius'', was Roman emperor from 284 until his abdication in 305. He was born Gaius Valerius Diocles ...
, windows, picture windows,
Rose window Rose window is often used as a generic term applied to a circular window, but is especially used for those found in Gothic cathedrals and churches. The windows are divided into segments by stone mullions and tracery. The term ''rose window'' w ...
s, emergency exit windows,
stained glass Stained glass is coloured glass as a material or works created from it. Throughout its thousand-year history, the term has been applied almost exclusively to the windows of churches and other significant religious buildings. Although tradition ...
windows, French windows, panel windows, double/triple-paned windows, and
witch window Witchcraft traditionally means the use of magic or supernatural powers to harm others. A practitioner is a witch. In medieval and early modern Europe, where the term originated, accused witches were usually women who were believed to have use ...
s. The Romans were the first known to use glass for windows, a technology likely first produced in
Roman Egypt , conventional_long_name = Roman Egypt , common_name = Egypt , subdivision = Province , nation = the Roman Empire , era = Late antiquity , capital = Alexandria , title_leader = Praefectus Augustalis , image_map = Roman E ...
, in
Alexandria Alexandria ( or ; ar, ٱلْإِسْكَنْدَرِيَّةُ ; grc-gre, Αλεξάνδρεια, Alexándria) is the second largest city in Egypt, and the largest city on the Mediterranean coast. Founded in by Alexander the Great, Alexandria ...
AD. Paper windows were economical and widely used in ancient China, Korea, and Japan. In England,
glass Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenching) of ...
became common in the windows of ordinary homes only in the early 17th century whereas windows made up of panes of flattened
animal horn Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
were used as early as the 14th century. In the 19th century American west,
greased paper window A greased paper window is a very inexpensive window made of paper coated in grease. The grease fills gaps between the paper fibers, reducing the amount of light lost to scattering. Greased paper windows provide a diffuse light source, while block ...
s came to be used by itinerant groups. Modern-style floor-to-ceiling windows became possible only after the industrial
plate Plate may refer to: Cooking * Plate (dishware), a broad, mainly flat vessel commonly used to serve food * Plates, tableware, dishes or dishware used for setting a table, serving food and dining * Plate, the content of such a plate (for example: ...
glass making Glass production involves two main methods – the float glass process that produces sheet glass, and glassblowing that produces bottles and other containers. It has been done in a variety of ways during the history of glass. Glass container ...
processes were fully perfected.


Etymology

The English language-word ''window'' originates from the
Old Norse Old Norse, Old Nordic, or Old Scandinavian, is a stage of development of North Germanic languages, North Germanic dialects before their final divergence into separate Nordic languages. Old Norse was spoken by inhabitants of Scandinavia and t ...
, from 'wind' and 'eye'. In
Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe *Norwegians, both a nation and an ethnic group native to Norway *Demographics of Norway *The Norwegian language, including the ...
,
Nynorsk Nynorsk () () is one of the two written standards of the Norwegian language, the other being Bokmål. From 12 May 1885, it became the state-sanctioned version of Ivar Aasen's standard Norwegian language ( no, Landsmål) parallel to the Dano-Nor ...
, and Icelandic, the Old Norse form has survived to this day (in Icelandic only as a less used word for a type of small open "window", not strictly a synonym for , the Icelandic word for 'window'). In
Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...
, the word remains as a term for a hole through the roof of a hut, and in the
Danish language Danish (; , ) is a North Germanic language spoken by about six million people, principally in and around Denmark. Communities of Danish speakers are also found in Greenland, the Faroe Islands, and the northern German region of Southern Schles ...
and Norwegian , the direct link to ''eye'' is lost, just as for ''window''. The Danish (but not the ) word is pronounced fairly similarly to ''window''. ''Window'' is first recorded in the early 13th century, and originally referred to an unglazed hole in a roof. ''Window'' replaced the
Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlement of Britain, Anglo ...
, which literally means 'eye-hole', and 'eye-door'. Many Germanic languages, however, adopted the Latin word to describe a window with glass, such as
standard Standard may refer to: Symbols * Colours, standards and guidons, kinds of military signs * Standard (emblem), a type of a large symbol or emblem used for identification Norms, conventions or requirements * Standard (metrology), an object th ...
Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...
, or
German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ger ...
. The use of ''window'' in English is probably because of the Scandinavian influence on the English language by means of
loanwords A loanword (also loan word or loan-word) is a word at least partly assimilated from one language (the donor language) into another language. This is in contrast to cognates, which are words in two or more languages that are similar because the ...
during the
Viking Age The Viking Age () was the period during the Middle Ages when Norsemen known as Vikings undertook large-scale raiding, colonizing, conquest, and trading throughout Europe and reached North America. It followed the Migration Period and the Ger ...
. In English, the word ''fenester'' was used as a parallel until the mid-18th century. ''Fenestration'' is still used to describe the arrangement of windows within a
façade A façade () (also written facade) is generally the front part or exterior of a building. It is a Loanword, loan word from the French language, French (), which means 'frontage' or 'face'. In architecture, the façade of a building is often t ...
, as well as ''
defenestration Defenestration (from Modern Latin ) is the act of throwing someone or something out of a window. The term was coined around the time of an incident in Prague Castle in the year 1618 which became the spark that started the Thirty Years' War. Th ...
'', meaning 'to throw out of a window'.


History

In the 13th century BC, the earliest windows were unglazed openings in a roof to admit light during the day. Later, windows were covered with animal hide, cloth, or wood. Shutters that could be opened and closed came next. Over time, windows were built that both protected the inhabitants from the elements and transmitted light, using multiple small pieces of translucent material, such as flattened pieces of translucent animal horn, thin slices of
marble Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or Dolomite (mineral), dolomite. Marble is typically not Foliation (geology), foliated (layered), although there are exceptions. In geology, the ...
, such as
fengite Fengite is a translucent sheet of marble or alabaster used during the Early Middle Ages for windows instead of glass Glass is a non- crystalline, often transparent, amorphous solid that has widespread practical, technological, and decora ...
, or pieces of glass, set in frameworks of wood, iron or lead. In the Far East, paper was used to fill windows. The Romans were the first known to use glass for windows, a technology likely first produced in Roman Egypt. Namely, in Alexandria ca. 100 AD cast glass windows, albeit with poor optical properties, began to appear, but these were small thick productions, little more than
blown glass Glassblowing is a glassforming technique that involves inflating molten glass into a bubble (or parison) with the aid of a blowpipe (or blow tube). A person who blows glass is called a ''glassblower'', ''glassmith'', or ''gaffer''. A '' lampworke ...
jars (cylindrical shapes) flattened out into sheets with circular striation patterns throughout. It would be over a millennium before window glass became transparent enough to see through clearly, as we think of it now. In 1154, Al-Idrisi described glass windows as a feature of the palace belonging to the king of the
Ghana Empire The Ghana Empire, also known as Wagadou ( ar, غانا) or Awkar, was a West African empire based in the modern-day southeast of Mauritania and western Mali that existed from c. 300 until 1100. The Empire was founded by the Soninke people, ...
. Over the centuries techniques were developed to shear through one side of a blown glass
cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infin ...
and produce thinner rectangular window panes from the same amount of glass material. This gave rise to tall narrow windows, usually separated by a vertical support called a mullion.
Mullion A mullion is a vertical element that forms a division between units of a window or screen, or is used decoratively. It is also often used as a division between double doors. When dividing adjacent window units its primary purpose is a rigid supp ...
ed glass windows were the windows of choice among European well-to-do, whereas paper windows were economical and widely used in ancient China, Korea, and Japan. In England, glass became common in the windows of ordinary homes only in the early 17th century whereas windows made up of panes of flattened animal horn were used as early as the 14th century. Modern-style floor-to-ceiling windows became possible only after the industrial
plate Plate may refer to: Cooking * Plate (dishware), a broad, mainly flat vessel commonly used to serve food * Plates, tableware, dishes or dishware used for setting a table, serving food and dining * Plate, the content of such a plate (for example: ...
glass making Glass production involves two main methods – the float glass process that produces sheet glass, and glassblowing that produces bottles and other containers. It has been done in a variety of ways during the history of glass. Glass container ...
processes were perfected. Modern windows are usually filled with glass, although a few are transparent plastic. File:Window grill from a palace of Ramesses III MET 14.6.232-dia1.jpg, Ancient Egyptian
sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...
window grill from a palace of
Ramesses III Usermaatre Meryamun Ramesses III (also written Ramses and Rameses) was the second Pharaoh of the Twentieth Dynasty in Ancient Egypt. He is thought to have reigned from 26 March 1186 to 15 April 1155 BC and is considered to be the last great monar ...
, now in the
Metropolitan Museum of Art The Metropolitan Museum of Art of New York City, colloquially "the Met", is the largest art museum in the Americas. Its permanent collection contains over two million works, divided among 17 curatorial departments. The main building at 1000 ...
(New York City) File:GBM - Glas Fenster.jpg, Fragment of a
Roman Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *''Epistle to the Romans'', shortened to ''Romans'', a letter ...
window glass plate dated to 1st to 4th century AD. Note the obvious curvature; this is not a flat pane File:Window art in Kalleshvara Temple at Aralaguppe (edited angles and cropped).jpg,
Indian Indian or Indians may refer to: Peoples South Asia * Indian people, people of Indian nationality, or people who have an Indian ancestor ** Non-resident Indian, a citizen of India who has temporarily emigrated to another country * South Asia ...
window of the Kalleshvara Temple (India) File:师俭堂.JPG,
Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of va ...
latticed window in Zhenze (
Jiangsu Jiangsu (; ; pinyin: Jiāngsū, Postal romanization, alternatively romanized as Kiangsu or Chiangsu) is an Eastern China, eastern coastal Provinces of the People's Republic of China, province of the China, People's Republic of China. It is o ...
, China) File:Atenas, varios 10.jpg,
Byzantine The Byzantine Empire, also referred to as the Eastern Roman Empire or Byzantium, was the continuation of the Roman Empire primarily in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantinopl ...
window of the
Little Metropolis The Little Metropolis ( el, Μικρή Μητρόπολη), formally the Church of St. Eleutherios () or Panagia Gorgoepikoos (, "Panagia Who Grants Requests Quickly"), is a Byzantine church located at the Mitropoleos Square (Cathedral of Athens), ...
(
Athens Athens ( ; el, Αθήνα, Athína ; grc, Ἀθῆναι, Athênai (pl.) ) is both the capital and largest city of Greece. With a population close to four million, it is also the seventh largest city in the European Union. Athens dominates ...
, Greece) File:Jameh Mosque of Nishapur - October 13 2013 45.JPG,
Islamic Islam (; ar, ۘالِإسلَام, , ) is an Abrahamic monotheistic religion centred primarily around the Quran, a religious text considered by Muslims to be the direct word of God (or '' Allah'') as it was revealed to Muhammad, the mai ...
window of the
Jameh Mosque of Nishapur The Jāmeh Mosque of Nishapur ( fa, مسجد جامع نیشابور - ''Masjid-e-Jāmeh Neyshabur'') is the grand congregational mosque ( Jāmeh Mosque) of the city of Nishapur in Iran. This mosque was founded by Pahlavan Ali Karkhi in 1493 dur ...
(
Nishapur Nishapur or officially Romanized as Neyshabur ( fa, ;Or also "نیشاپور" which is closer to its original and historic meaning though it is less commonly used by modern native Persian speakers. In Persian poetry, the name of this city is wr ...
,
Iran Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
) File:David et Salomon, vitrail roman, Cathédrale de Strasbourg.jpg, Part of a Romanesque stained glass window with Kings
David David (; , "beloved one") (traditional spelling), , ''Dāwūd''; grc-koi, Δαυΐδ, Dauíd; la, Davidus, David; gez , ዳዊት, ''Dawit''; xcl, Դաւիթ, ''Dawitʿ''; cu, Давíдъ, ''Davidŭ''; possibly meaning "beloved one". w ...
and
Solomon Solomon (; , ),, ; ar, سُلَيْمَان, ', , ; el, Σολομών, ; la, Salomon also called Jedidiah (Hebrew language, Hebrew: , Modern Hebrew, Modern: , Tiberian Hebrew, Tiberian: ''Yăḏīḏăyāh'', "beloved of Yahweh, Yah"), ...
from Cathédrale Notre-Dame de Strasbourg (
Strasbourg Strasbourg (, , ; german: Straßburg ; gsw, label=Bas Rhin Alsatian, Strossburi , gsw, label=Haut Rhin Alsatian, Strossburig ) is the prefecture and largest city of the Grand Est region of eastern France and the official seat of the Eu ...
, France) File:Chartres RosetteNord 121 DSC08241.jpg, North transept windows in the
Chartres Cathedral Chartres Cathedral, also known as the Cathedral of Our Lady of Chartres (french: Cathédrale Notre-Dame de Chartres), is a Roman Catholic church in Chartres, France, about southwest of Paris, and is the seat of the Bishop of Chartres. Mostly con ...
(
Chartres Chartres () is the prefecture of the Eure-et-Loir department in the Centre-Val de Loire region in France. It is located about southwest of Paris. At the 2019 census, there were 170,763 inhabitants in the metropolitan area of Chartres (as d ...
, France) File:Valdai IverskyMon asv2018 img41.jpg,
Russian Russian(s) refers to anything related to Russia, including: *Russians (, ''russkiye''), an ethnic group of the East Slavic peoples, primarily living in Russia and neighboring countries *Rossiyane (), Russian language term for all citizens and peo ...
window of the
Valday Iversky Monastery Valday Iversky Monastery (russian: Валдайский Иверский монастырь) is a Russian Orthodox monastery founded by Patriarch Nikon in 1653. The monastery is located on an island in Lake Valdayskoye in Valdaysky District of Novg ...
(
Lake Valdayskoye Lake Valdayskoye, or Lake Valdai (russian: Валдайское озеро, озеро Валдай, translit = ozero Valdai) is a freshwater lake located in the center of Valdaysky District of Novgorod Oblast in Russia in the middle of the Val ...
,
Novgorod Oblast Novgorod Oblast (russian: Новгоро́дская о́бласть, ''Novgorodskaya oblast'') is a federal subject of Russia (an oblast). Its administrative center is the city of Veliky Novgorod. Some of the oldest Russian cities, including ...
, Russia) File:Flickr - fusion-of-horizons - stavropoleos (124).jpg, Brâncovenesc window of the Stavropoleos Monastery (
Bucharest Bucharest ( , ; ro, București ) is the capital and largest city of Romania, as well as its cultural, industrial, and financial centre. It is located in the southeast of the country, on the banks of the Dâmbovița River, less than north of ...
, Romania) File:Fenetre-assezat-cour (2).jpg,
Renaissance The Renaissance ( , ) , from , with the same meanings. is a period in European history marking the transition from the Middle Ages to modernity and covering the 15th and 16th centuries, characterized by an effort to revive and surpass ideas ...
window of the
Hôtel d'Assézat The Hôtel d'Assézat in Toulouse, France, is a French Renaissance ''hôtel particulier'' (urban palace) of the 16th century which houses the Bemberg Foundation, a major art gallery of the city. The hôtel was likely built by Toulouse architect N ...
(
Toulouse Toulouse ( , ; oc, Tolosa ) is the prefecture of the French department of Haute-Garonne and of the larger region of Occitania. The city is on the banks of the River Garonne, from the Mediterranean Sea, from the Atlantic Ocean and from Par ...
, France) File:0756a - Milano - Palazzo Sormani-Andreani - Foto Giovanni Dall'Orto 5-May-2007 (edited).jpg,
Baroque The Baroque (, ; ) is a style of architecture, music, dance, painting, sculpture, poetry, and other arts that flourished in Europe from the early 17th century until the 1750s. In the territories of the Spanish and Portuguese empires including t ...
window of the
Palazzo Sormani Palazzo Sormani (also known as Palazzo Sormani-Andreani or cà Sormana in Milanese dialect) is a historic building of Milan, Italy, and the seat of the central public library of Milan. It is located at number 6 in Corso di Porta Vittoria, in the ...
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Milan Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city h ...
, Italy) File:Zwinger Wallpavillon Gartenseite, Dresden.jpg,
Rococo Rococo (, also ), less commonly Roccoco or Late Baroque, is an exceptionally ornamental and theatrical style of architecture, art and decoration which combines asymmetry, scrolling curves, gilding, white and pastel colours, sculpted moulding, ...
windows of the
Zwinger "" () is a German word for outer ward or bailey (castle), outer bailey. It represents an open kill zone area between two defensive walls that is used for defensive purposes. s were built in the Post-classical history, post-classical and early ...
(
Dresden Dresden (, ; Upper Saxon: ''Dräsdn''; wen, label=Upper Sorbian, Drježdźany) is the capital city of the German state of Saxony and its second most populous city, after Leipzig. It is the 12th most populous city of Germany, the fourth larg ...
, Germany) File:South gate of the Petit Trianon 004.JPG,
Louis XVI Louis XVI (''Louis-Auguste''; ; 23 August 175421 January 1793) was the last King of France before the fall of the monarchy during the French Revolution. He was referred to as ''Citizen Louis Capet'' during the four months just before he was ...
round window of the
Petit Trianon The Petit Trianon (; French for "small Trianon") is a Neoclassical style château located on the grounds of the Palace of Versailles in Versailles, France. It was built between 1762 and 1768 during the reign of King Louis XV of France. T ...
(
Versailles The Palace of Versailles ( ; french: Château de Versailles ) is a former royal residence built by King Louis XIV located in Versailles, about west of Paris, France. The palace is owned by the French Republic and since 1995 has been managed, u ...
, France), with a
festoon A festoon (from French ''feston'', Italian ''festone'', from a Late Latin ''festo'', originally a festal garland, Latin ''festum'', feast) is a wreath or garland hanging from two points, and in architecture typically a carved ornament depicti ...
-derived ornament at the top File:Window of a lateral façade of the Romanian Athenaeum, on Strada Benjamin Franklin (Bucharest, Romania).jpg, Neoclassical group of windows, on a lateral side of the
Romanian Athenaeum The Romanian Athenaeum ( ro, Ateneul Român) is a concert hall in the center of Bucharest, Romania, and a landmark of the Romanian capital city. Opened in 1888, the ornate, domed, circular building is the city's most prestigious concert hall an ...
(Bucharest) File:Window of a very beautiful Gothic Revival house on the Jean-Louis Calderon street from Bucharest (Romania).jpg,
Gothic Revival Gothic Revival (also referred to as Victorian Gothic, neo-Gothic, or Gothick) is an architectural movement that began in the late 1740s in England. The movement gained momentum and expanded in the first half of the 19th century, as increasingly ...
window of a house on Strada Jean-Louis Calderon (Bucharest) File:P1340760 Paris II place et passage du Caire rwk.jpg,
Egyptian Revival Egyptian Revival is an architectural style that uses the motifs and imagery of ancient Egypt. It is attributed generally to the public awareness of ancient Egyptian monuments generated by Napoleon's conquest of Egypt and Admiral Nelson's defeat ...
windows of a building in Place du Caire (Paris) File:60, Bulevardul Dacia, Bucharest (Romania) 1.jpg, Romanian Revival window of a house on Bulevardul Dacia (Bucharest) File:Window, 55 rue Molitor, Paris 25 February 2017.jpg, 19th century
Eclectic Eclectic may refer to: Music * ''Eclectic'' (Eric Johnson and Mike Stern album), 2014 * ''Eclectic'' (Big Country album), 1996 * Eclectic Method, name of an audio-visual remix act * Eclecticism in music, the conscious use of styles alien to th ...
Classicist windows on Rue Molitor (Paris) File:9, Strada Dianei, Bucharest (Romania) 3.jpg, Beaux-Arts window of the Stroescu House on Strada Dianei (Bucharest) File:Top corner facade of former chamber of commerce Grenoble.jpg,
Art Nouveau Art Nouveau (; ) is an international style of art, architecture, and applied art, especially the decorative arts. The style is known by different names in different languages: in German, in Italian, in Catalan, and also known as the Modern ...
windows of the Former Chamber of Commerce Building in
Grenoble lat, Gratianopolis , commune status = Prefecture and commune , image = Panorama grenoble.png , image size = , caption = From upper left: Panorama of the city, Grenoble’s cable cars, place Saint- ...
(France) File:Stillemans32.jpg,
Art Deco Art Deco, short for the French ''Arts Décoratifs'', and sometimes just called Deco, is a style of visual arts, architecture, and product design, that first appeared in France in the 1910s (just before World War I), and flourished in the Unite ...
house with stained glass windows on Stillemansstraat (
Sint-Niklaas Sint-Niklaas (; french: Saint-Nicolas, ) is a Belgian city and municipality located in the Flemish province of East Flanders. The municipality comprises the city of Sint-Niklaas proper and the towns of Belsele, Nieuwkerken-Waas, and . Sint-Nikl ...
, Belgium) File:Windows of the Cité de la musique, Paris July 2015.jpg,
Postmodern Postmodernism is an intellectual stance or mode of discourseNuyen, A.T., 1992. The Role of Rhetorical Devices in Postmodernist Discourse. Philosophy & Rhetoric, pp.183–194. characterized by skepticism toward the " grand narratives" of moderni ...
windows of the Cité de la musique (Paris) File:Windows (7004083002).jpg,
Contemporary Contemporary history, in English-language historiography, is a subset of modern history that describes the historical period from approximately 1945 to the present. Contemporary history is either a subset of the late modern period, or it is o ...
windows of
Cathedral Plaza Bucharest Cathedral Plaza is an illegal office building in Bucharest, Romania, close to the Saint Joseph Cathedral. It has 19 floors and a surface of 23,000 m2. At a height of 75 m (246 ft), the structure was finished in 2010, but the building was ...
File:Fönster - Entré - Ystad-2021.jpg, Very high windows in the entrance to a residential building in
Ystad Ystad (; older da, Ysted) is a town and the seat of Ystad Municipality, in Scania County, Sweden. Ystad had 18,350 inhabitants in 2010. The settlement dates from the 11th century and has become a busy ferryport, local administrative centre, and ...
.


Types


Cross

A
cross-window A cross-window is a window whose lights are defined by a mullion and a transom, forming a cross.Curl, James Stevens (2006). ''Oxford Dictionary of Architecture and Landscape Architecture'', 2nd ed., OUP, Oxford and New York, p. 214. . The Late ...
is a rectangular window usually divided into four lights by a mullion and transom that form a
Latin cross A Latin cross or ''crux immissa'' is a type of cross in which the vertical beam sticks above the crossbeam, with the three upper arms either equally long or with the vertical topmost arm shorter than the two horizontal arms, and always with a mu ...
.


Eyebrow

The term eyebrow window is used in two ways: a curved top window in a wall or an eyebrow
dormer A dormer is a roofed structure, often containing a window, that projects vertically beyond the plane of a pitched roof. A dormer window (also called ''dormer'') is a form of roof window. Dormers are commonly used to increase the usable space ...
; and a row of small windows usually under the front eaves such as the
James-Lorah House James-Lorah House, also known as the Judge Chapman House and VIA House, is a historic home located in Doylestown, Bucks County, Pennsylvania. It was built about 1844, and is a -story, stuccoed townhouse dwelling with a medium gable roof. It has ...
in Pennsylvania.


Fixed

A fixed window is a window that cannot be opened, whose function is limited to allowing light to enter (unlike an unfixed window, which can open and close). Clerestory windows in
church architecture Church architecture refers to the architecture of buildings of churches, convents, seminaries etc. It has evolved over the two thousand years of the Christian religion, partly by innovation and partly by borrowing other architectural styles as ...
are often fixed. Transom windows may be fixed or operable. This type of window is used in situations where light or vision alone is needed as no ventilation is possible in such windows without the use of
trickle vent A trickle vent is a very small opening in a window or other building envelope component to allow small amounts of ventilation in spaces intended to be naturally ventilated when major elements of the design – windows, doors, etc., are othe ...
s or overglass vents.


Single-hung sash

A single-hung sash window is a window that has one sash that is movable (usually the bottom one) and the other fixed. This is the earlier form of sliding sash window and is also cheaper.


Double-hung sash

A
sash window A sash window or hung sash window is made of one or more movable panels, or "sashes". The individual sashes are traditionally paned window (architecture), paned windows, but can now contain an individual sheet (or sheets, in the case of double gla ...
is the traditional style of window in the United Kingdom, and many other places that were formerly colonized by the UK, with two parts (sashes) that overlap slightly and slide up and down inside the frame. The two parts are not necessarily the same size; where the upper sash is smaller (shorter) it is termed a
cottage window A cottage window is a double-hung window — i.e., a window with two sashes sliding up and down, hung with one atop the other in the same frame — in which the upper sash is smaller (shorter) than the lower one. The upper sash often contains ...
. Currently, most new double-hung sash windows use spring balances to support the sashes, but traditionally, counterweights held in boxes on either side of the window were used. These were and are attached to the sashes using pulleys of either braided cord or, later, purpose-made chain. Three types of spring balances are called a tape or clock spring balance; channel or block-and-tackle balance, and a spiral or tube balance. Double-hung sash windows were traditionally often fitted with shutters. Sash windows can be fitted with simplex hinges that let the window be locked into hinges on one side, while the rope on the other side is detached—so the window can be opened for fire escape or cleaning.


Foldup

A foldup has two equal sashes similar to a standard double-hung but folds upward allowing air to pass through nearly the full-frame opening. The window is balanced using either springs or counterbalances, similar to a double-hung. The sashes can be either offset to simulate a double-hung, or in-line. The inline versions can be made to fold inward or outward. The inward swinging foldup windows can have fixed screens, while the outward swinging ones require movable screens. The windows are typically used for screen rooms, kitchen pass-throughs, or egress.


Horizontal sliding sash

A horizontal sliding sash window has two or more sashes that overlap slightly but slide horizontally within the frame. In the UK, these are sometimes called
Yorkshire Yorkshire ( ; abbreviated Yorks), formally known as the County of York, is a Historic counties of England, historic county in northern England and by far the largest in the United Kingdom. Because of its large area in comparison with other Eng ...
sash windows, presumably because of their traditional use in that county.


Casement

A casement window is a window with a hinged sash that swings in or out like a door comprising either a side-hung, top-hung (also called "awning window"; see below), or occasionally bottom-hung sash or a combination of these types, sometimes with fixed panels on one or more sides of the sash. In the US, these are usually opened using a crank, but in parts of Europe, they tend to use projection friction stays and
espagnolette An espagnolette is a locking device, normally mounted on the vertical frame of a French door or casement window. A handle or knob is connected to a metal rod mounted to the surface of the frame, about a metre above the floor. Operating the handle ...
locking. Formerly, plain hinges were used with a casement stay.
Handing A door is a hinged or otherwise movable barrier that allows ingress (entry) into and egress (exit) from an enclosure. The created opening in the wall is a ''doorway'' or ''portal''. A door's essential and primary purpose is to provide security b ...
applies to casement windows to determine direction of swing; a casement window may be left-handed, right-handed, or double. The casement window is the dominant type now found in modern buildings in the UK and many other parts of Europe.


Awning

An awning window is a casement window that is hung horizontally,
hinge A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation: all other ...
d on top, so that it swings outward like an
awning An awning or overhang is a secondary covering attached to the exterior wall of a building. It is typically composed of canvas woven of acrylic, cotton or polyester yarn, or vinyl laminated to polyester fabric that is stretched tightly over a lig ...
. In addition to being used independently, they can be stacked, several in one opening, or combined with fixed glass. They are particularly useful for ventilation.


Hopper

A hopper window is a bottom-pivoting casement window that opens by tilting vertically, typically to the inside, resembling a
hopper Hopper or hoppers may refer to: Places *Hopper, Illinois * Hopper, West Virginia * Hopper, a mountain and valley in the Hunza–Nagar District of Pakistan * Hopper (crater), a crater on Mercury People with the name * Hopper (surname) * Grace H ...
chute.


Pivot

A pivot window is a window hung on one hinge on each of two opposite sides which allows the window to revolve when opened. The hinges may be mounted top and bottom (Vertically Pivoted) or at each jamb (Horizontally Pivoted). The window will usually open initially to a restricted position for ventilation and, once released, fully reverse and lock again for safe cleaning from inside. Modern pivot hinges incorporate a friction device to hold the window open against its weight and may have restriction and reversed locking built-in. In the UK, where this type of window is most common, they were extensively installed in high-rise social housing.


Tilt and slide

A tilt and slide window is a window (more usually a door-sized window) where the sash tilts inwards at the top similar to a hopper window and then slides horizontally behind the fixed pane.


Tilt and turn

A tilt and turn window can both tilt inwards at the top or open inwards from hinges at the side. This is the most common type of window in Germany, its country of origin. It is also widespread in many other European countries. In Europe, it is usual for these to be of the "turn first" type. i.e. when the handle is turned to 90 degrees the window opens in the side hung mode. With the handle turned to 180 degrees the window opens in bottom hung mode. Most usually in the UK the windows will be "tilt first" i.e. bottom hung at 90 degrees for ventilation and side hung at 180 degrees for cleaning the outer face of the glass from inside the building.


Transom

A window above a door; in an exterior door the
transom Transom may refer to: * Transom (architecture), a bar of wood or stone across the top of a door or window, or the window above such a bar * Transom (nautical), that part of the stern of a vessel where the two sides of its hull meet * Operation Tran ...
window is often fixed, in an interior door, it can open either by hinges at top or bottom, or rotate on hinges. It provided ventilation before forced air heating and cooling. A fan-shaped transom is known as a fanlight, especially in the British Isles.


Side light

Windows beside a door or window are called side-, wing-, margen-lights, and flanking windows.


Jalousie window

Also known as a
louver A louver (American English) or louvre (British English British English (BrE, en-GB, or BE) is, according to Lexico, Oxford Dictionaries, "English language, English as used in Great Britain, as distinct from that used elsewhere". Mor ...
ed window, the
jalousie window A jalousie window (, ) or louvered window (Australia, New Zealand, Pacific Islands, Southeast Asia, United Kingdom) is a window composed of parallel glass, acrylic, or wooden louvres set in a frame. The louvres are joined onto a track so that ...
consists of parallel slats of glass or
acrylic Acrylic may refer to: Chemicals and materials * Acrylic acid, the simplest acrylic compound * Acrylate polymer, a group of polymers (plastics) noted for transparency and elasticity * Acrylic resin, a group of related thermoplastic or thermosett ...
that open and close like a
Venetian blind A window blind is a type of window covering. There are many different kinds of window blinds which use a variety of control systems. A typical window blind is made up of several long horizontal or vertical slats of various types of hard mater ...
, usually using a crank or a lever. They are used extensively in tropical architecture. A jalousie door is a door with a jalousie window.


Clerestory

A clerestory window is a window set in a
roof A roof ( : roofs or rooves) is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of temper ...
structure or high in a wall, used for
daylighting Daylighting is the practice of placing windows, skylights, other openings, and Reflective surfaces (climate engineering), reflective surfaces so that sunlight (direct or indirect) can provide effective internal lighting. Particular attention is ...
.


Skylight

A skylight is a window built into a roof structure. This type of window allows for natural daylight and moonlight.


Roof

A sloped window used for
daylighting Daylighting is the practice of placing windows, skylights, other openings, and Reflective surfaces (climate engineering), reflective surfaces so that sunlight (direct or indirect) can provide effective internal lighting. Particular attention is ...
, built into a roof structure. It is one of the few windows that could be used as an exit. Larger
roof window A roof window is an outward opening window that is incorporated as part of the design of a roof. Often confused with a skylight, a roof window differs in a few basic ways. A roof window is often a good option when there is a desire to allow both ...
s meet building codes for emergency evacuation.


Roof lantern

A roof lantern is a multi-paned glass structure, resembling a small building, built on a roof for day or moon light. Sometimes includes an additional
clerestory In architecture, a clerestory ( ; , also clearstory, clearstorey, or overstorey) is a high section of wall that contains windows above eye level. Its purpose is to admit light, fresh air, or both. Historically, ''clerestory'' denoted an upper l ...
. May also be called a
cupola In architecture, a cupola () is a relatively small, most often dome-like, tall structure on top of a building. Often used to provide a lookout or to admit light and air, it usually crowns a larger roof or dome. The word derives, via Italian, from ...
.


Bay

A bay window is a multi-panel window, with at least three panels set at different angles to create a protrusion from the wall line.


Oriel

This form of bay window most often appears in Tudor-style houses and monasteries. It projects from the wall and does not extend to the ground. Originally a form of porch, they are often supported by brackets or corbels.


Thermal

Thermal, or Diocletian, windows are large semicircular windows (or niches) which are usually divided into three lights (window compartments) by two mullions. The central compartment is often wider than the two side lights on either side of it.


Picture

A picture window is a large fixed window in a wall, typically without glazing bars, or glazed with only perfunctory glazing bars (
muntin A muntin (US), muntin bar, glazing bar (UK), or sash bar is a strip of wood or metal separating and holding panes of glass in a window. Muntins can be found in doors, windows, and furniture, typically in Western styles of architecture. Muntins ...
s) near the edge of the window. Picture windows provide an unimpeded view, as if framing a picture.


Multi-lite

A multi-lite window is a window glazed with small panes of glass separated by wooden or lead ''glazing bars'', or ''
muntins A muntin (US), muntin bar, glazing bar (UK), or sash bar is a strip of wood or metal separating and holding panes of glass in a window. Muntins can be found in doors, windows, and furniture, typically in Western styles of architecture. Muntins ...
'', arranged in a decorative ''glazing pattern'' often dictated by the building's architectural style. Due to the historic unavailability of large panes of glass, the multi-lit (or ''lattice window'') was the most common window style until the beginning of the 20th century, and is still used in traditional architecture.


Emergency exit/egress

An emergency exit window is a window big enough and low enough so that occupants can escape through the opening in an emergency, such as a fire. In many countries, exact specifications for emergency windows in bedrooms are given in many
building codes A building code (also building control or building regulations) is a set of rules that specify the standards for constructed objects such as buildings and non-building structures. Buildings must conform to the code to obtain planning permission ...
. Specifications for such windows may also allow for the entrance of emergency rescuers. Vehicles, such as buses, aircraft, and trains frequently have emergency exit windows as well.


Stained glass

A stained glass window is a window composed of pieces of colored glass, transparent, translucent or
opaque Opacity or opaque may refer to: * Impediments to (especially, visible) light: ** Opacities, absorption coefficients ** Opacity (optics), property or degree of blocking the transmission of light * Metaphors derived from literal optics: ** In lingu ...
, frequently portraying persons or scenes. Typically the glass in these windows is separated by lead glazing bars. Stained glass windows were popular in Victorian houses and some Wrightian houses, and are especially common in churches.


French

A French door has two rows of upright rectangular glass panes (lights) extending its full length; and two of these doors on an exterior wall and without a
mullion A mullion is a vertical element that forms a division between units of a window or screen, or is used decoratively. It is also often used as a division between double doors. When dividing adjacent window units its primary purpose is a rigid supp ...
separating them, that open outward with opposing hinges to a
terrace Terrace may refer to: Landforms and construction * Fluvial terrace, a natural, flat surface that borders and lies above the floodplain of a stream or river * Terrace, a street suffix * Terrace, the portion of a lot between the public sidewalk a ...
or porch, are referred to as a French window. Sometimes these are set in pairs or multiples thereof along the exterior wall of a very large room, but often, one French window is placed centrally in a typically sized room, perhaps among other fixed windows flanking the feature. French windows are known as ''porte-fenêtre'' in France and ''portafinestra'' in Italy, and frequently are used in modern houses.


Double-paned

Double-paned windows have two parallel panes (slabs of glass) with a separation of typically about 1 cm; this space is permanently sealed and filled at the time of manufacture with dry air or other dry nonreactive gas. Such windows provide a marked improvement in thermal insulation (and usually in acoustic insulation as well) and are resistant to fogging and frosting caused by temperature differential. They are widely used for residential and commercial construction in intemperate climates. In the UK, double-paned and triple-paned are referred to as double-glazing and triple-glazing. Triple-paned windows are now a common type of glazing in central to northern Europe.
Quadruple glazing Standard quadruple glazed window - openable The quadruple glazing, Q-Air, on Deg 8 building in Oslo, Norway (2020). Renovation brings Ug value of 0,29 W/(m2K) -value 20Quadruple glazing (quadruple-pane insulating glazing) is a type of insulated ...
is now being introduced in Scandinavia.


Hexagonal window

A hexagonal window is a hexagon-shaped window, resembling a bee cell or crystal lattice of graphite. The window can be vertically or horizontally oriented, openable or dead. It can also be regular or elongately-shaped and can have a separator (
mullion A mullion is a vertical element that forms a division between units of a window or screen, or is used decoratively. It is also often used as a division between double doors. When dividing adjacent window units its primary purpose is a rigid supp ...
). Typically, the cellular window is used for an attic or as a decorative feature, but it can also be a major architectural element to provide the natural lighting inside buildings.


Guillotine window

A guillotine window is a window that opens vertically. The guillotine windows are opening from bottom to top or from top to bottom with more than one sliding frames. The remote control can be used to open and close guillotine windows.


Terms

EN 12519 is the European standard that describes windows terms officially used in EU Member States. The main terms are: * Light, or Lite, is the area between the outer parts of a window (
transom Transom may refer to: * Transom (architecture), a bar of wood or stone across the top of a door or window, or the window above such a bar * Transom (nautical), that part of the stern of a vessel where the two sides of its hull meet * Operation Tran ...
, sill and jambs), usually filled with a glass pane. Multiple panes are divided by
mullion A mullion is a vertical element that forms a division between units of a window or screen, or is used decoratively. It is also often used as a division between double doors. When dividing adjacent window units its primary purpose is a rigid supp ...
s when load-bearing,
muntin A muntin (US), muntin bar, glazing bar (UK), or sash bar is a strip of wood or metal separating and holding panes of glass in a window. Muntins can be found in doors, windows, and furniture, typically in Western styles of architecture. Muntins ...
s when not. * Lattice light is a compound window pane madeup of small pieces of glass held together in a
lattice Lattice may refer to: Arts and design * Latticework, an ornamental criss-crossed framework, an arrangement of crossing laths or other thin strips of material * Lattice (music), an organized grid model of pitch ratios * Lattice (pastry), an ornam ...
. * Fixed window is a unit of one non-moving lite. The terms ''single-light'', ''double-light'', etc., refer to the number of these glass panes in a window. * Sash unit is a window consisting of at least one sliding glass component, typically composed of two lites (known as a ''double-light''). * Replacement window in the United States means a framed window designed to slip inside the original window frame from the inside after the old sashes are removed. In Europe, it usually means a complete window including a replacement outer frame. * New construction window, in the US, means a window with a nailing fin that is inserted into a rough opening from the outside before applying siding and inside trim. A nailing fin is a projection on the outer frame of the window in the same plane as the glazing, which overlaps the prepared opening, and can thus be 'nailed' into place. :In the UK and mainland Europe, windows in new-build houses are usually fixed with long screws into expanding plastic plugs in the brickwork. A gap of up to 13 mm is left around all four sides, and filled with expanding
polyurethane foam Polyurethane products have many uses. Over three quarters of the global consumption of polyurethane products is in the form of foams, with flexible and rigid types being roughly equal in market size. In both cases, the foam is usually behind othe ...
. This makes the window fixing weatherproof but allows for expansion due to heat. *
Lintel A lintel or lintol is a type of beam (a horizontal structural element) that spans openings such as portals, doors, windows and fireplaces. It can be a decorative architectural element, or a combined ornamented structural item. In the case of w ...
is a beam over the top of a window, also known as a
transom Transom may refer to: * Transom (architecture), a bar of wood or stone across the top of a door or window, or the window above such a bar * Transom (nautical), that part of the stern of a vessel where the two sides of its hull meet * Operation Tran ...
. *
Window sill A windowsill (also written window sill or window-sill, and less frequently in British English, cill) is the horizontal structure or surface at the bottom of a window. Window sills serve to structurally support and hold the window in place. The ...
is the bottom piece in a window frame. Window sills slant outward to drain water away from the inside of the building. * Secondary glazing is an additional frame applied to the inside of an existing frame, usually used on protected or listed buildings to achieve higher levels of thermal and sound insulation without compromising the look of the building * Decorative millwork is the moulding, cornices and lintels often decorating the surrounding edges of the window.


Labeling

The United States NFRC Window Label lists the following terms: * Thermal transmittance (U-factor), best values are around U-0.15 (equal to 0.8 W/m2/K) *
Solar heat gain coefficient Solar gain (also known as solar heat gain or passive solar gain) is the increase in thermal energy of a space, object or structure as it absorbs incident solar radiation. The amount of solar gain a space experiences is a function of the total in ...
(SHGC), ratio of solar heat (infrared) passing through the glass to incident solar heat *
Visible transmittance Transmittance of the surface of a material is its effectiveness in transmitting radiant energy. It is the fraction of incident electromagnetic power that is transmitted through a sample, in contrast to the transmission coefficient, which is th ...
(VT), ratio of transmitted visible light divided by incident visible light * Air leakage (AL), measured in cubic foot per minute per linear foot of crack between sash and frame * Condensation resistance (CR), measured between 1 and 100 (the higher the number, the higher the resistance of the formation of condensation) The European harmonised standard hEN 14351–1, which deals with doors and windows, defines 23 characteristics (divided into ''essential'' and ''non ''essential''). Two other, preliminary European Norms that are under development deal with internal pedestrian doors (prEN 14351–2), smoke and fire resisting doors, and openable windows (prEN 16034).


Construction

Windows can be a significant source of heat transfer.Carmody, J., Selkowitz, S., Lee, E. S., Arasteh, D., & Willmert, T. (2004). ''Window Systems for High-Performance Buildings''. New York, NY: W. W. Norton & Company, Inc. Therefore,
insulated glazing Insulating glass (IG) consists of two or more glass window panes separated by a space to reduce heat transfer across a part of the building envelope. A window with insulating glass is commonly known as double glazing or a double-paned window, ...
units consist of two or more panes to reduce the transfer of heat.


Grids or muntins

These are the pieces of framing that separate a larger window into smaller panes. In older windows, large panes of glass were quite expensive, so muntins let smaller panes fill a larger space. In modern windows, light-colored muntins still provide a useful function by reflecting some of the light going through the window, making the window itself a source of diffuse light (instead of just the surfaces and objects illuminated within the room). By increasing the indirect illumination of surfaces near the window, muntins tend to brighten the area immediately around a window and reduce the contrast of shadows within the room.


Frame and sash construction

Frames and sashes can be made of the following materials: Composites (also known as Hybrid Windows) are start since early 1998 and combine materials like aluminium + pvc or wood to obtain aesthetics of one material with the functional benefits of another. A special class of PVC window frames, uPVC window frames, became widespread since the late 20th century, particularly in Europe: there were 83.5 million installed by 1998 with numbers still growing as of 2012.


Glazing and filling

Low-emissivity Low emissivity (low ''e'' or low thermal emissivity) refers to a surface condition that emits low levels of radiant thermal (heat) energy. All materials absorb, reflect, and emit radiant energy according to Planck's law but here, the primary conc ...
coated panes reduce heat transfer by
radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...
, which, depending on which surface is coated, helps prevent heat loss (in cold climates) or heat gains (in warm climates). High thermal resistance can be obtained by evacuating or filling the insulated glazing units with gases such as
argon Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abu ...
or
krypton Krypton (from grc, κρυπτός, translit=kryptos 'the hidden one') is a chemical element with the symbol Kr and atomic number 36. It is a colorless, odorless, tasteless noble gas that occurs in trace amounts in the atmosphere and is often ...
, which reduces
conductive In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. Electric current is gener ...
heat transfer due to their low thermal conductivity. Performance of such units depends on good window seals and meticulous frame construction to prevent entry of air and loss of efficiency. Modern double-pane and triple-pane windows often include one or more low-e coatings to reduce the window's U-factor (its insulation value, specifically its rate of heat loss). In general, soft-coat low-e coatings tend to result in a lower solar heat gain coefficient (SHGC) than hard-coat low-e coatings. Modern windows are usually glazed with one large sheet of glass per sash, while windows in the past were glazed with multiple panes separated by ''glazing bars'', or ''muntins'', due to the unavailability of large sheets of glass. Today, glazing bars tend to be decorative, separating windows into small panes of glass even though larger panes of glass are available, generally in a pattern dictated by the architectural style at use. Glazing bars are typically wooden, but occasionally lead glazing bars soldered in place are used for more intricate glazing patterns.


Other construction details

Many windows have movable
window covering Window coverings are considered any type of materials used to cover a window to manage sunlight, privacy, additional weatherproofing or for purely decorative purposes. Window coverings are typically used on the interior side of windows, but exte ...
s such as
blinds A window blind is a type of window covering. There are many different kinds of window blinds which use a variety of control systems. A typical window blind is made up of several long horizontal or vertical slats of various types of hard mater ...
or
curtain A curtain is a piece of cloth or other material intended to block or obscure light, air drafts, or (in the case of a shower curtain), water. A curtain is also the movable screen or drape in a theatre that separates the stage from the auditorium ...
s to keep out light, provide additional insulation, or ensure privacy. Windows allow natural light to enter, but too much can have negative effects such as glare and heat gain. Additionally, while windows let the user see outside, there must be a way to maintain privacy on in the inside.Howell, Sandra C. (1976). ''Designing for the Elderly; Windows''. Massachusetts Institute of Technology. Department of Architecture. Design Evaluation Project. Window coverings are practical accommodations for these issues.


Impact of the sun


Sun incidence angle

Historically, windows are designed with surfaces parallel to vertical building walls. Such a design allows considerable solar light and heat penetration due to the most commonly occurring incidence of sun angles. In
passive solar building design In passive solar building design, windows, walls, and floors are made to collect, store, reflect, and distribute solar energy, in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design because, unli ...
, an extended
eave The eaves are the edges of the roof which overhang the face of a wall and, normally, project beyond the side of a building. The eaves form an overhang to throw water clear of the walls and may be highly decorated as part of an architectural styl ...
is typically used to control the amount of solar light and heat entering the window(s). An alternative method is to calculate an optimum window mounting angle that accounts for summer sun load minimization, with consideration of actual latitude of the building. This process has been implemented, for example, in the
Dakin Building The Dakin Building is an architectural award-winning class A office building on the San Francisco Bay in Brisbane, California. Serving as a corporate headquarters building for several companies of national prominence, it was built from the profit ...
in
Brisbane, California Brisbane (pron. , unlike Brisbane, Queensland, Australia) is a small city located in California in the northern part of San Mateo County on the lower slopes of San Bruno Mountain. It is located on the southern border of San Francisco, on the ...
—in which most of the fenestration is designed to reflect summer heat load and help prevent summer interior
over-illumination Overillumination is the presence of lighting intensity higher than that which is appropriate for a specific activity. Overillumination was commonly ignored between 1950 and 1995, especially in office and retail environments.M.D. Simpson, ''A fl ...
and glare, by canting windows to nearly a 45 degree angle.


Solar window

Photovoltaic windows not only provide a clear view and illuminate rooms, but also convert sunlight to electricity for the building. In most cases, translucent photovoltaic cells are used.


Passive solar

Passive solar windows allow light and solar energy into a building while minimizing air leakage and heat loss. Properly positioning these windows in relation to sun, wind, and landscape—while properly shading them to limit excess heat gain in summer and shoulder seasons, and providing thermal mass to absorb energy during the day and release it when temperatures cool at night—increases comfort and energy efficiency. Properly designed in climates with adequate solar gain, these can even be a building's primary heating system.


Coverings

A
window covering Window coverings are considered any type of materials used to cover a window to manage sunlight, privacy, additional weatherproofing or for purely decorative purposes. Window coverings are typically used on the interior side of windows, but exte ...
is a shade or screen that provides multiple functions. Some coverings, such as drapes and blinds provide occupants with privacy. Some window coverings control solar heat gain and glare. There are external shading devices and internal shading devices.Beckett, H. E., & Godfrey, J. A. (1974). ''Windows: Performance, design and installation''. New York, NY: Van Nostrand Reinhold Company. Low-e
window film Window film (tint) is a thin laminate film that can be installed to the interior or exterior of glass surfaces in automobiles and boats and also to the interior or exterior of glass in homes and buildings. It is usually made from polyethylene ter ...
is a low-cost alternative to window replacement to transform existing poorly-insulating windows into energy-efficient windows. For high-rise buildings,
smart glass Smart glass or switchable glass (also called a smart window or switchable window) is a glass or glazing whose light transmission properties dynamically alter to control the passage of solar irradiation into buildings. In general, the glass chan ...
can provide an alternative.


See also

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Airflow window An airflow window is composed of at least two panes of glass and a cavity between them that allows the flow of ventilation air. They operate on similar principles to a double-skin facade, but on a smaller scale. The general idea is to improve the en ...
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Architectural glass Architectural glass is glass that is used as a building material. It is most typically used as transparent glazing material in the building envelope, including windows in the external walls. Glass is also used for internal partitions and as an ar ...
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Demerara window Demerara windows were built primarily into 18th- and 19th-century Colonial architecture-styled buildings to cool homes in hot climates, such as Guyana, before the invention of air conditioning. Demerara is a historical region of Guyana. The win ...
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Display window A display window, also a shop window (British English) or store window (American English), is a window in a shop displaying items for sale or otherwise designed to attract customers to the store. Usually, the term refers to larger windows in the f ...
* Fenestration testing laboratory *
Fortochka A fortochka ( rus, фо́рточка, p=ˈfortətɕkə, a=Ru-форточка.ogg) is a small ventilation window. It usually spans the frame of one window pane and opens on hinges independently of the whole window. Fortochkas are in common use ...
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Glass mullion system Glass mullion system or glass fin system is a glazing system in which sheets of tempered glass are suspended from special clamps, stabilized by perpendicular stiffeners of tempered glass, and joined by a structural silicone sealant or by metal pat ...
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Greased paper window A greased paper window is a very inexpensive window made of paper coated in grease. The grease fills gaps between the paper fibers, reducing the amount of light lost to scattering. Greased paper windows provide a diffuse light source, while block ...
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Insulated glazing Insulating glass (IG) consists of two or more glass window panes separated by a space to reduce heat transfer across a part of the building envelope. A window with insulating glass is commonly known as double glazing or a double-paned window, ...
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Porthole A porthole, sometimes called bull's-eye window or bull's-eye, is a generally circular window used on the hull of ships to admit light and air. Though the term is of maritime origin, it is also used to describe round windows on armored vehicles ...
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Rose window Rose window is often used as a generic term applied to a circular window, but is especially used for those found in Gothic cathedrals and churches. The windows are divided into segments by stone mullions and tracery. The term ''rose window'' w ...
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Window tax Window tax was a property tax based on the number of windows in a house. It was a significant social, cultural, and architectural force in England, France, and Ireland during the 18th and 19th centuries. To avoid the tax, some houses from the pe ...
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Window treatment A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent materi ...
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Witch window Witchcraft traditionally means the use of magic or supernatural powers to harm others. A practitioner is a witch. In medieval and early modern Europe, where the term originated, accused witches were usually women who were believed to have use ...


References


External links


Roman Glass from Metropolitan Museum of Art
{{Authority control Architectural elements Glass