# Louver

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Window protection with horizontal angled slats

For other uses, see [Louvre (disambiguation)](/source/Louvre_(disambiguation)).

"Louvre (window)" redirects here. For windows composed of louvres, see [Jalousie window](/source/Jalousie_window).

This article needs more citations. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Louver" – news · newspapers · books · scholar · JSTOR (May 2013) (Learn how and when to remove this message)

Concept drawing of a louver [gable](/source/Gable) vent

Louvers used in a [Stevenson screen](/source/Stevenson_screen)

Louver exterior shutters in Italy

Louvered [cupola](/source/Cupola) bell house

A **louver** ([American](/source/American_English)) or **louvre** ([Commonwealth English](/source/Commonwealth_English); [see spelling differences](/source/American_and_British_English_spelling_differences#-re,_-er)) is a framed opening fitted with horizontal [slats](https://en.wiktionary.org/wiki/slat) in a structure. These slats (also sometimes called louvers/louvres) are angled to [admit light](/source/Daylighting_(architecture)) and [air](/source/Ventilation_(architecture)), as well as to [keep out rain](/source/Weatherization) and direct [sunshine](/source/Sunlight). The angle of the slats may be adjustable, usually in [blinds](/source/Window_blind) and [windows](/source/Jalousie_window), or fixed, such as in exterior [shutters](/source/Window_shutter).[1][2]

## History

Louvers originated in the [Middle Ages](/source/Middle_Ages) as lantern-like constructions in wood that were fitted on top of roof holes in large kitchens to allow ventilation while keeping out rain and snow. They were originally rather crude constructions consisting merely of a barrel.

Later, they evolved into more elaborate designs made of pottery, taking the shape of faces where the smoke and steam from cooking would pour out through the eyes and mouth, or into constructions that were more like modern louvers, with slats that could be opened or closed by pulling on a string.[3]

## Construction

Modern louvers are often made of [aluminum](/source/Aluminum), metal, wood, or glass. They may be opened and closed with a metal lever, pulleys, or through motorized operators.[4]

The Australian Standard specifies requirements for the construction of buildings using louver in [bushfire](/source/Wildfire)-prone areas in order to improve their resistance to bushfire attack from burning embers, radiant heat, flame contact and combinations of the three attack forms.[5][6] The revised building standard details various construction methods and materials that must be used depending on the homes level of bushfire risk. This includes changes to the window and glazing requirements for homes located in a Bushfire Attack Level category greater than BAL-Low.

## Jalousies

Often used interchangeably by mistake, the key difference between louvers and [jalousies](/source/Jalousie_window) is that louvers are fixed position. Jalousies are installed within a movable adjustable mechanism which positions all jalousies into any parallel position with respect to each other.[7]

## Use

### In architecture

The belfry louvers of [Sens Cathedral](/source/Sens_Cathedral), France

Louvers are rarely seen as primary design elements in the language of [modern architecture](/source/Modern_architecture), but rather simply a technical device. Louvers are part of the design of [Demerara windows](/source/Demerara_window) to help keep 18th and 19th century buildings cool in hot climates and block direct sunlight.[8][9] Some modern louver systems serve to improve indoor [daylighting](/source/Daylighting_(architecture)). Fixed [mirrored](/source/Mirror) louver systems can limit glare and of redirect diffuse light. Such louvers may be integrated in between two panes of [double glazing](/source/Double_glazing).[10] In industrial facilities such as steel [foundries](/source/Foundry) and [power plants](/source/Power_station), louvers are very common. They are utilized for natural ventilation and temperature control.

Louvers are frequently found in [bell towers](/source/Bell_tower), where they are utilised to let out as much sound as possible, while having the bells remain unexposed to the weather.

There are examples of architects who use louvers as part of the overall aesthetic effect of their buildings. The most well-known example is Finnish modernist architect [Alvar Aalto](/source/Alvar_Aalto) who would create aesthetic effects in the facades of his buildings through the combination of different types and sizes of louvers, some fixed some moveable, and made mostly from wood (e.g., the various buildings of the [Helsinki University of Technology](/source/Helsinki_University_of_Technology)). A second example, taking influence from Aalto, is the second-generation modernist architect [Juha Leiviskä](/source/Juha_Leivisk%C3%A4).

### In infrastructure

Louvers may be used as a type of [flood opening](/source/Flood_opening), usually covered by one or more moving flaps. They are designed to allow [floodwaters](/source/Flood) to enter and leave the building, equalizing [hydrostatic pressure](/source/Hydrostatic_pressure) on the walls and mitigating structural damage due to flooding. Louver windows are a staple in the design of homes and perfect to withstand the pressures of future cyclonic conditions.[11] Cyclone homes have always been synonymous with louver windows, louver blades have been tested for 'debris type B' for cyclonic regions.

### In transportation

Louvers mounted to the rear window of a 1970 [AMC Javelin](/source/AMC_Javelin)

[Rear window louvers](/source/Window_deflector#Rear_window_louvers) are also available as an accessory for some automobiles. They have also been used over the years in hoods, trunk lids, and other various body panels; typically [hot rods](/source/Hot_rod), but by no means exclusive to that period. Their purpose in this regard is both as a functional means of ventilation, but also as a styling modification.

Louvers are used as semi-passive means of thermal control on [airplanes](/source/Airplanes) and [spacecraft](/source/Spacecraft) as well.[12]

Louvers may also be used on [traffic light](/source/Traffic_light) [lenses](/source/Traffic_light#Programmable_visibility_signals) to prevent traffic from seeing the wrong traffic signal.

## See also

Look up ***[louver](https://en.wiktionary.org/wiki/Special:Search/louver)*** in Wiktionary, the free dictionary.

- [Air conditioning](/source/Air_conditioning)

- [Jalousie window](/source/Jalousie_window)

- [Window shutter](/source/Window_shutter)

## References

Wikimedia Commons has media related to [Louvers](https://commons.wikimedia.org/wiki/Category:Louvers).

**Notes**

1. **[^](#cite_ref-TFD-1_1-0)** ["louver"](https://thefreedictionary.com/louver). Retrieved 2 March 2014 – via [The Free Dictionary](/source/The_Free_Dictionary).

1. **[^](#cite_ref-2)** ["Shutters vs. Blinds"](https://shuttercraft.co.uk/blog/window-dressings/what-should-i-choose-shutters-vs-blinds). Shuttercraft Ltd. Retrieved 7 February 2025.

1. **[^](#cite_ref-3)** Henisch (1976), pp. 96–97.

1. **[^](#cite_ref-EB-1_4-0)** ["Louver from "Encyclopædia Britannica""](https://www.britannica.com/EBchecked/topic/349399/louver). *Encyclopædia Britannica*. Retrieved 2 March 2014.{{[cite encyclopedia](https://en.wikipedia.org/wiki/Template:Cite_encyclopedia)}}: CS1 maint: deprecated archival service ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_deprecated_archival_service))

1. **[^](#cite_ref-5)** ["Specifying Louvres in Bushfire Prone Areas"](https://safetylinejalousie.com.au/specifying-louvres-in-bushfire-prone-areas/). *SafetyLine Jalousie*. 18 September 2018. Retrieved 18 September 2018.

1. **[^](#cite_ref-6)** ["Building in designated bushfire prone areas"](https://www.planning.vic.gov.au/guides-and-resources/guides/all-guides/building-in-bushfire-prone-areas). *[Department of Transport and Planning](/source/Department_of_Transport_and_Planning)*. [Shade It](https://shadeitblinds.ca/). 2023-11-21. Retrieved 2025-10-08.

1. **[^](#cite_ref-7)** Architectural Terms & Definitions Textbook

1. **[^](#cite_ref-Westmas_8-0)** Rory, Westmas (31 May 2010). ["Architecture - Building Under the Sun"](https://www.stabroeknews.com/2010/guyana-review/05/31/architecture/). *Stabroek News*. Retrieved 2 June 2018.

1. **[^](#cite_ref-Murtland_9-0)** Haley, Murtland (23 April 2017). ["The Demerara Window – the Colonial 'AC'"](https://www.kaieteurnewsonline.com/2017/04/23/the-demerara-window-the-colonial-ac/). *Kaieteur News*. Retrieved 2 June 2018.

1. **[^](#cite_ref-10)** Dariusz Heim and Kamil Kieszkowski: [Shading Devices Designed to Achieve the Desired Quality of Internal Daylight Environment](http://www.unige.ch/cuepe/html/plea2006/Vol2/PLEA2006_PAPER786.pdf) [Archived](https://web.archive.org/web/20110607033118/http://www.unige.ch/cuepe/html/plea2006/Vol2/PLEA2006_PAPER786.pdf) 2011-06-07 at the [Wayback Machine](/source/Wayback_Machine), PLEA2006 - The 23rd Conference on Passive and Low Energy Architecture, Geneva, Switzerland, 6–8 September 2006

1. **[^](#cite_ref-11)** ["A Timely Reminder Why Louvre Windows Were Specified in Queensland Cyclone Shelters"](https://safetylinejalousie.com.au/a-timely-reminder-why-louvre-windows-were-specified-in-queensland-cyclone-shelters/). *SafetyLine Jalousie*. 29 March 2017. Retrieved 29 March 2017.

1. **[^](#cite_ref-12)** ["Frequently asked questions / Rosetta / Space Science / Our Activities / ESA"](http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions). Retrieved 24 May 2014.{{[cite web](https://en.wikipedia.org/wiki/Template:Cite_web)}}: CS1 maint: deprecated archival service ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_deprecated_archival_service)) "The system devised for Rosetta employs several new techniques, including the installation of louvres over the radiators, to keep spacecraft hardware at proper operating temperatures"

**Bibliography**

- Henisch, Bridget Ann *Fast and Feast: Food in Medieval Society*. The Pennsylvania State Press, University Park. 1976. [ISBN](/source/ISBN_(identifier)) [0-271-01230-7](https://en.wikipedia.org/wiki/Special:BookSources/0-271-01230-7)

- ["Foundation Flood Vents"](http://toolbase.org/about.aspx). National Association of Home Builders (NAHB) Research Center. 2001.{{[cite web](https://en.wikipedia.org/wiki/Template:Cite_web)}}: CS1 maint: deprecated archival service ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_deprecated_archival_service))

v t e Heating, ventilation, and air conditioning Fundamental concepts Air changes per hour (ACH) Bake-out Building envelope Convection Dilution Domestic energy consumption Enthalpy Fluid dynamics Gas compressor Heat pump and refrigeration cycle Heat transfer Humidity Infiltration Latent heat Noise control Outgassing Particulates Psychrometrics Sensible heat Stack effect Thermal comfort Thermal destratification Thermal mass Thermodynamics Vapour pressure of water Technology Absorption-compression heat pump Absorption refrigerator Air barrier Air conditioning Antifreeze Automobile air conditioning Autonomous building Building insulation materials Central heating Central solar heating Chilled beam Chilled water Constant air volume (CAV) Coolant Cross ventilation Dedicated outdoor air system (DOAS) Deep water source cooling Demand controlled ventilation (DCV) Displacement ventilation District cooling District heating Electric heating Energy recovery ventilation (ERV) Firestop Forced-air Forced-air gas Free cooling Heat recovery ventilation (HRV) Hybrid heat Hydronics Ice storage air conditioning Kitchen ventilation Mixed-mode ventilation Microgeneration Passive cooling Passive daytime radiative cooling Passive house Passive ventilation Radiant heating and cooling Radiant cooling Radiant heating Radon mitigation Raised floor Refrigeration Renewable heat Room air distribution Solar air heat Solar combisystem Solar cooling Solar heating Thermal insulation Thermosiphon Underfloor air distribution Underfloor heating Vapor barrier Vapor-compression refrigeration (VCRS) Variable air volume (VAV) Variable refrigerant flow (VRF) Ventilation Water heat recycling Components Air conditioner inverter Air door Air filter Air handler Air ionizer Air-mixing plenum Air purifier Air source heat pump Attic fan Automatic balancing valve Back boiler Barrier pipe Blast damper Boiler Centrifugal fan Ceramic heater Chiller Condensate pump Condenser Condensing boiler Convection heater Compressor Cooling tower Damper Dehumidifier Duct Economizer Electrostatic precipitator Evaporative cooler Evaporator Exhaust hood Expansion tank Fan Fan coil unit Fan filter unit Fan heater Fire damper Fireplace Fireplace insert Freeze stat Flue Freon Fume hood Furnace Gas compressor Gas heater Gasoline heater Grease duct Grille Ground-coupled heat exchanger Ground source heat pump Heat exchanger Heat pipe Heat pump Heating film Heating system HEPA High efficiency glandless circulating pump High-pressure cut-off switch Humidifier Infrared heater Inverter compressor Kerosene heater Louver Mechanical room Oil heater Packaged terminal air conditioner Plenum space Pressurisation ductwork Process duct work Radiator Radiator reflector Recuperator Refrigerant Register Reversing valve Run-around coil Sail switch Scroll compressor Solar chimney Solar-assisted heat pump Space heater Smoke canopy Smoke damper Smoke exhaust ductwork Thermal expansion valve Thermal wheel Thermostatic radiator valve Trickle vent Trombe wall TurboSwing Turning vanes Ultra-low particulate air (ULPA) Whole-house fan Windcatcher Wood-burning stove Zone valve Measurement and control Air flow meter Aquastat BACnet Blower door Building automation Carbon dioxide sensor Clean air delivery rate (CADR) Control valve Gas detector Home energy monitor Humidistat HVAC control system Infrared thermometer Intelligent buildings LonWorks Minimum efficiency reporting value (MERV) Normal temperature and pressure (NTP) OpenTherm Programmable communicating thermostat Programmable thermostat Psychrometrics Room temperature Smart thermostat Standard temperature and pressure (STP) Thermographic camera Thermostat Thermostatic radiator valve Professions, trades, and services Architectural acoustics Architectural engineering Architectural technologist Building services engineering Building information modeling (BIM) Deep energy retrofit Duct cleaning Duct leakage testing Environmental engineering Hydronic balancing Kitchen exhaust cleaning Mechanical engineering Mechanical, electrical, and plumbing Mold growth, assessment, and remediation Refrigerant reclamation Testing, adjusting, balancing Industry organizations AHRI AMCA ASHRAE ASTM International BRE BSRIA CIBSE Institute of Refrigeration IIR LEED SMACNA UMC Health and safety Indoor air quality (IAQ) Passive smoking Sick building syndrome (SBS) Volatile organic compound (VOC) See also ASHRAE Handbook Building science Fireproofing Glossary of HVAC terms Warm Spaces World Refrigeration Day Template:Fire protection Template:Home automation Template:Plumbing Template:Solar energy

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Adapted from the Wikipedia article [Louver](https://en.wikipedia.org/wiki/Louver) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Louver?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.