View source for Clerestory

{{Short description|Windows in wall above eye level}}
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{{Use dmy dates|date=May 2024}}
{{Use British English |date=March 2024}}
[[File:Clerestory diagram.png|thumb|upright|Interior elevation of a [[Gothic cathedral]], with clerestory highlighted]]
[[File:Stralsund, st Nikolai (2007-01-24) d.JPG|thumb|The church of [[St. Nicholas' Church (Stralsund)|St Nicholas, Stralsund]] in Germany {{Ndash}}the clerestory is the level between the two green roofs, reinforced here by [[flying buttress]]es]]

A '''clerestory''' ({{IPAc-en|ˈ|k|l|ɪər|s|t|ɔːr|i}} {{respell|KLEER|stor|ee}}; {{literally|clear storey}}, also '''clearstory''', '''clearstorey''', or '''overstorey'''; from {{langx|fro|cler estor}}) is a high section of wall that contains [[window]]s above eye-level. Its purpose is to admit light, fresh air, or both.

Historically, a clerestory formed an upper level of a Roman [[basilica]] or of the [[nave]] of a [[Romanesque architecture|Romanesque]] or [[Gothic architecture|Gothic]] [[church (building)|church]], the walls of which rise above the rooflines of the lower [[aisle]]s and which are pierced with windows.

In addition to [[architecture]], clerestories have been [[#Transportation|used in transportation vehicles]] such as buses and trains to provide additional lighting, ventilation, or headroom.

==History==
[[File:Monreale.jpg|thumb|The walls of the clerestory of the [[Basilica#Christian adoption of the basilica form|basilica-shaped]] [[Monreale Cathedral|Cathedral of Monreale]], Italy, covered with [[mosaic]]s]]

===Ancient world===
[[File:History of architecture 0152b.jpg|thumb|Front-view profile of Great Hypostyle Hall, an early example of a clerestory.|left]]
Clerestories appear to originate in [[Egyptian temple]]s, such as the [[Great Hypostyle Hall]],<ref name="KleinerGardner">Kleiner, Fred S. Gardner's Art Through the Ages. 14th. Boston: Wadsworth, 73. Print.</ref> where the lighting of the hall of columns was obtained over the stone roofs of the adjoining aisles, through gaps left in the vertical slabs of stone. They appeared in Egypt at least as early as the [[Amarna Period]].<ref>Gwendolyn Leick and Francis J. Kirk, ''A Dictionary of Ancient Near Eastern Architecture'', 1988, Routledge, 261 pages {{ISBN|0-415-00240-0}}</ref> [[Minoan palaces]] in [[Crete]] such as [[Knossos]]  employed  [[lightwell]]s in addition to clerestories.<ref>C. Michael Hogan, [http://www.themodernantiquarian.com/site/10854/knossos.html#fieldnotes ''Knossos fieldnotes'', Modern Antiquarian (2007)]</ref>

According to the [[Hebrew Bible]], [[Solomon's Temple]] featured clerestory windows made possible by the use of a tall, angled roof and a central {{linktext|ridgepole}}.<ref name="Palmer2008">{{cite book|last=Palmer|first=Allison Lee|title=Historical Dictionary of Architecture|url=https://books.google.com/books?id=FHR9sHRfQ_0C&pg=PA267|access-date=2014-06-15|date=2008-09-11|publisher=Scarecrow Press|isbn=978-0-8108-6283-8|page=267}}</ref>

The clerestory was used in the [[Hellenistic art#Architecture|Hellenistic architecture]] of [[classical antiquity]]. The Romans applied clerestories to [[basilica]]s of justice and to the basilica-like [[thermae]] and palaces.

===Early Christian and Byzantine basilicas===
[[Early Christianity|Early Christian]] churches and some Byzantine churches, particularly in Italy, are based closely on the Roman basilica, and maintained the form of a central [[nave]] flanked by lower aisles on each side. The nave and aisles are separated by columns or piers, above which rises a wall pierced by clerestory windows.
[[File:malmesbury.abbey.clerestory.arp.jpg|thumb|upright|[[Malmesbury Abbey]], [[Wiltshire]], England. The nave wall is divided into three stages: the upper stage with windows is the clerestory, beneath it is the triforium, and the lowest stage is the arcade.]]

===Romanesque period===
During the [[Romanesque architecture|Romanesque]] period, many churches of the basilica form were constructed all over Europe. Many of these churches have wooden roofs with clerestories below them. Some Romanesque churches have [[barrel-vaulted]] ceilings with no clerestory. The development of the [[groin vault]] and [[ribbed vault]] made possible the insertion of clerestory windows.

Initially the nave of a large aisled and clerestoried church was of two levels: [[Arcade (architecture)|arcade]] and clerestory. During the Romanesque period, a third level was inserted between them, a gallery called the "[[triforium]]". The triforium generally opens into space beneath the sloping roof of the aisle. This became a standard feature of later Romanesque and Gothic large abbey and cathedral churches. Sometimes another gallery set into the wall space above the triforium and below the clerestory. This feature is found in some late Romanesque and early Gothic buildings in France.

The oldest glass clerestory windows still in place are from the late eleventh century, found in [[Augsburg Cathedral]] in [[Bavaria]], Germany.

===Gothic period===
[[File:Cathedrale d'Amiens - Grandes verrieres et voutes de la nef.jpg|thumb|left|upright|The clerestory of [[Amiens Cathedral]] in northern France]]
In smaller churches, clerestory windows may be [[trefoil]]s or [[quatrefoil]]s. In some Italian churches they are [[Rose Window#Oculi|ocular]]. In most large churches, they are an important feature, both for beauty and for utility. The [[ribbed vault]]ing and [[flying buttress]]es of Gothic architecture concentrated the weight and thrust of the roof, freeing wall-space for larger clerestory [[Fenestration (architecture)|fenestration]]. Generally, in Gothic masterpieces, the clerestory is divided into [[bay (architecture)|bays]] by the vaulting shafts that continue the same tall columns that form the arcade separating the aisles from the nave.

The tendency from the early Romanesque period to the late Gothic period was for the clerestory level to become progressively taller and the size of the windows to get proportionally larger in relation to wall surface, emerging in works such as the Gothic architecture of [[Amiens Cathedral]] or [[Westminster Abbey]], where their clerestories account for nearly a third of the height of the interior.<ref name="Simpson1922">{{cite book|last=Simpson|first=Frederick Moore|title=History of Architectural Development|url=https://books.google.com/books?id=8MFCAAAAYAAJ&pg=PA273|year=1922|publisher=Longmans, Green, and Company|page=273}}</ref>

== Today ==
[[File:874Rizal Cainta Roads Buildings Landmarks 29.jpg|thumb|Modern clerestories of Holy Trinity Parish Church in [[Cainta, Rizal]], Philippines]]

Modern clerestories often are defined as vertical windows, located on high walls, extending up from the roofline, designed to allow light and breezes into a space, without compromising privacy. Factory buildings often are built with clerestory windows; modern housing designs sometimes include them as well.

Modern clerestory windows may have another especially important role, besides [[Daylighting (architecture)|daylighting]] and [[natural ventilation|ventilation]]: they can be part of [[passive solar]] strategies, in very energy-efficient buildings ([[passive house]]s and [[zero-energy building]]s).<ref>[http://www.greenbuildingadvisor.com/green-basics/siting-sun-passive-heating-and-daylighting "Siting with the Sun: Passive Heating and Daylighting"] {{Webarchive|url=https://web.archive.org/web/20180711225445/http://www.greenbuildingadvisor.com/green-basics/siting-sun-passive-heating-and-daylighting |date=11 July 2018 }}. GreenBuildingAdvisor.com</ref>

To that end, clerestories are used in conjunction with stone, brick, concrete, and other high-mass walls and floors, properly positioned to store [[solar heat gain]]s during the hotter parts of the day – allowing the walls and the floor to act as a heat bank during the cooler parts of the day.<ref>[http://www.house-energy.com/Windows/Clerestory.html "Clerestory Windows: Advantages and Downsides"]. House-energy.com.</ref>
[[File:Russo-Balt (Valmieras iela, Riga).JPG|thumb|[[Russo-Balt]] factory building with clerestory in [[Riga]], Latvia]]
Clerestories – in passive solar strategies – should be properly located (typically in the sunny side of the building) and protected from the summer's sun by rooflines, [[Overhang (architecture)|overhangs]], recessed thick walls, or other architectural elements, in order to prevent overheating during the cooling season.

{{anchor|Clerestory (transport)}}

==In transportation==
[[Image:Passenger car GN 3261 20041010.jpg|thumb|[[Barney and Smith Car Company]] clerestory-roofed passenger cars at the [[Mid-Continent Railway Museum]]. As in these examples, later clerestory roofs ended in a bullnose.<span class="anchor" id="bullnose"></span>]]<!--Please leave. Text in ''Bullnose'' article links here.-->

[[File:Clerestory roof interior, Type B tram car no 42, Tramway Museum St Kilda, South Australia.jpg|thumb|Interior of the clerestory roof of a 1908-vintage tram at the [[Tramway Museum, St Kilda|Tramway Museum, St Kilda, South Australia]], showing how it provides improved light and ventilation]]

Clerestory roofs were incorporated into the designs of many [[Passenger car (rail)|railway passenger cars]] and [[tram]]s [[Commonwealth English]]) / streetcars ([[American English]] & [[Canadian English]]) from about 1860<ref>{{cite web |url=https://www.trains.com/trn/railroads/history/civil-war-rails/ |title=Remembering Civil War rails | last=Hankey |first=John P. |date=21 January 2011 |website=[[Trains (magazine)|Trains]] |publisher=[[Kalmbach Media]] |access-date=20 January 2025}}{{spaces|2|en}}[[File:Lock-gray-alt-2.svg|9px|link=|alt=Free registration required|Free registration required]] <code>registration</code>: a free registration is required to access the source.</ref> to the 1930s.<ref>{{citation| url=https://books.google.com/books?id=ESnBiR7vLPQC| title = World railways of the nineteenth century: a pictorial history in Victorian engravings|first =Jim |last= Harter| publisher= Johns Hopkins University Press| year= 2005|page=248| isbn= 9780801880896}}</ref><ref>{{citation| title= Railway carriages, 1839-1939| first=G.M.|last= Kichenside| publisher=Ian Allan| year= 1964| at= Clerestory Roofs, p.12| url =https://books.google.com/books?id=-nEEAAAAMAAJ}}</ref> They increased the daylight and ventilation available to passengers.

In the US, the railroad clerestory roof was also known as the "lantern roof".

The first [[Pullman (car or coach)|Pullman coaches]] in the UK had clerestory roofs. They were imported from the US and assembled at Derby, where Pullman set up an assembly plant in conjunction with the [[Midland Railway]], a predecessor of the [[London Midland and Scottish Railway]] (LMS). The first coach, a sleeping car named "Midland", was assembled and ready for trial-running in January 1874.<ref>{{cite book|last1=Radford | first1 = J B | title = The American Cars of the Midland Railway | location = London | publisher = Ian Allan | page = 15 etc. | year = 1984 | isbn = 0-7110-1387-X}}</ref>

In the UK when coaches were equipped with gas lighting, a clerestory was normally incorporated to improve ventilation near the lamps, in order to improve combustion and reduce the risk of carbon monoxide poisoning.

The last clerestory-roofed trains on the [[London Underground]] were the [[London Underground Q Stock|'Q' stock]], which were withdrawn from operation in 1971.<ref>{{cite web|title=RW Carroll Collection|url=https://www.flickr.com/photos/robertcwp/7148066675/in/photostream/lightbox/|website=Flickr|date=6 May 2012 |access-date=22 July 2015}}</ref>

Clerestories were also used in early British [[double-decker bus]]es, giving better [[ventilation (architecture)|ventilation]] and headroom in the centre corridor, as well as better [[illumination (lighting)|illumination]].<ref>{{citation|url =https://books.google.com/books?id=9_U9AAAAIAAJ| title = The Golden Age of Buses| first =Charles F.| last = Klapper| publisher = Routledge| year= 1984| orig-year=1978| page=16| isbn = 9780710202321}}</ref>

The [[Volkswagen Type 2]] Kombi, or Transport, commonly called the Microbus, came in a deluxe version with clerestory windows. VW made the Samba from 1961 to 1967 in several versions, which had as many as 23 windows, and it is highly prized by collectors.

In the UK, the style is also known as "mollycroft roof", especially in [[Romani people|Romany]] caravans, such as [[Vardo (Romani wagon)|vardo]]s, and other caravans.
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==See also==
 {{div col|colwidth=23em}}
* [[Architecture of cathedrals and great churches]]
* [[Gothic architecture]]
* [[Daylighting (architecture)|Passive daylighting]]
* [[Romanesque architecture]]
* [[Roof window]]
* [[Säteritak]], a Swedish roof style with a strip of clerestory-type of windows halfway up a hip roof
 {{div col end}}
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==References==
{{reflist}}

==External links==
{{commons category|Clerestories}}
* [https://www.flickr.com/groups/2031425@N22/ Clerestory coach (railway) images] – nineteenth-century examples from more than 20 countries

{{Roofs}}

[[Category:Church architecture]]
[[Category:Windows]]
[[Category:Architectural elements]]
[[Category:Energy-saving lighting]]
[[Category:Sustainable building]]