Editing Window (section)

=== Frame and sash construction ===

Frames and sashes can be made of the following materials:
{| class="wikitable"
! Material
! [[Thermal resistance]]
! Durability
! Maintenance
! Cost
! Recycled content
! Comment
|-
| [[Wood]]
| very good
| variable
| low
| average
| high
| a well-maintained wood window built before 1950 can last 50–100 years<ref>{{cite web |title=Saving Windows, Saving Money: Evaluating the Energy Performance of Window Retrofit and Replacement |url=https://forum.savingplaces.org/viewdocument/saving-windows-saving-money-evalu |website=Resource Library – National Trust for Historic Preservation |publisher=National Trust for Historic Preservation |access-date=March 31, 2020}}</ref><ref name="auto">{{cite web |last1=Peterson Wasielewski |first1=Shannon |title=Windows: Energy Efficiency Facts and Myths |url=https://dahp.wa.gov/sites/default/files/Windows%20Energy%20Efficiency%20Facts%20and%20Myths.pdf |website=Washington Department of Archaeology and Historic Preservation |access-date=March 31, 2020}}</ref>
|-
| [[Polyvinyl chloride|uPVC ("vinyl")]]
| very good
| very good{{Efn-lr|PVC and fiberglass frames perform well in accelerated weathering tests. Because PVC is not as strong as other materials, some PVC frames are reinforced with metal or composite materials to improve their structural strength.|name=PVC&fiberglass}}
| very low
| average
| very low
| has a life span of 25–50 years in average<ref name="auto" />
|-
| [[Aluminum]]
| very good{{Efn-lr|1=Modern aluminium window frames are typically separated by a thermal break made of a glass fibre reinforced polyamide. With a 34&nbsp;mm thermal insulation profile it is possible to reach Uf= 1.3 W/m2K for a metal window. This greatly increases thermal resistance, while retaining virtually all of the structural strength.}}
| good
| very low
| low
| typically >&nbsp;95%
| mostly thermally broken by a thermal insulation profile
|-
|Composites
|very good
|good
|very low
|high
|high
|used in modern buildings
|-
| [[Steel]]
| medium
| superior
| very low
| high
| >&nbsp;98%
| typically welded at corner joints
|-
| [[Fiberglass]]
| very good
| very good{{Efn-lr|name=PVC&fiberglass}}
| very low
| high
| medium
|
|}
{{Notelist-lr}}[[composite material|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.
[[File:Bleekman zimmer.jpg|thumb|A typical installation of insulated glazing windows with uPVC window frames]]
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<ref>{{cite book|last1=Pritchard|first1=Geoffrey|title=Novel and Traditional Fillers for Plastics: Technology and Market Developments|year=1999|publisher=iSmithers Rapra Publishing|isbn=978-1-85957-183-5|page=95|url=https://books.google.com/books?id=U3GWoyuMEckC&pg=PA95}}</ref> with numbers still growing as of 2012.<ref>{{cite web|url=http://www.prweb.com/releases/Vinyl_doors_market/vinyl_windows_market/prweb9415523.htm|archive-url=https://archive.today/20130131182428/http://www.prweb.com/releases/Vinyl_doors_market/vinyl_windows_market/prweb9415523.htm|url-status=dead|archive-date=January 31, 2013|title=Global Vinyl Windows Market to Reach 163 Million Units by 2017, According to a New Report by Global Industry Analysts, Inc. |publisher=PRWeb|date=April 18, 2012|access-date=February 11, 2012}}</ref>