Energy Efficient Windows Can Melt Vinyl Siding

The Effect of Reflected Sunlight from Low-e and other Double Paned Window Glass on Vinyl Siding:

OVERVIEW

Glass in double paned windows may on occasion slightly warp or deflect due to a difference in barometric pressure between the interior of the glass panes and the outside air pressure. This can create a concavity in the glass. Such a concavity is a normal response to pressure differences, does not affect the performance of the window, and does not constitute a defective window condition. However,the concavity may focus sunlight reflected from the window in a fashion similar to the effect seen when light passes through a magnifying glass. The heat generated by the focused reflected sunlight has proven sufficient to visibly damage and distort vinyl siding on nearby houses. Any double paned window may cause this effect, but double paned low-e windows have a higher reflectivity quotient which can exacerbate the reflected light/vinyl distortion phenomenon.

VINYL SIDING

The Vinyl Siding Institute (VSI) states that temperature ranges beginning at 160-165 degrees Fahrenheit can soften normal grades of vinyl siding. Darker colors absorb more heat, and will soften before lighter colors of siding. Heat generated from double paned low-e window reflected sunlight has been measured in excess of 200 degrees Fahrenheit, more than sufficient to soften and distort any normal grade or color of vinyl siding. There have been some reports of reflected sunlight damage to materials other than vinyl siding. Occasional wood discoloration and charring, and damage to paint and other plastics (e.g.,decking, window lineals, trim), have all been reported.

REFLECTED SUNLIGHT EFFECT

The use of double paned low-e windows will not necessarily result in any damaging reflected sunlight incident. A combination of contributing factors must be present before the effect occurs or causes damage to any nearby materials, including vinyl siding. The presence of the concavity in the double glass panes (resulting in the magnifying glass effect with a focused light beam) appears to be the primary cause of the heat generation, more so than the mere increased reflectivity of the low-e window. The angle of the sun is also a factor. A low angle of sunlight (such as might occur in late fall, winter, or early spring) is more likely to produce the effect. Other factors, such as proximity to the adjoining house, wind speed, air temperature, and the presence of buffering foliage are all said to have an impact on whether a damaging reflected sunlight effect does in fact occur.

Vinyl siding and insulating windows both have very large market penetration. Vinyl siding has been the most used siding product on new single-family homes in the U.S. every year since 1994. It was applied to 35% of all new homes built during that time frame. The majority of new vinylsided homes are in the south (40%), midwest (35%), and northeast (19%) (U.S. Census Bureau 2009). Based on sales data and projections from 1999 to 2019, approximately 45% of residential vinyl siding is, or will be, used in the new construction market; the remainder will be used for retrofits and repairs (Freedonia Group, Inc. 2009).

The U.S. Department of Energy and model energy codes have made improved residential energy efficiency a national priority. Therefore, standards have called for increasingly stringent energy efficiency requirements for windows. The performance levels achieved by insulating windows are mandated by nearly all local building energy codes for both new construction and replacement in existing buildings. Windows are typically designed to meet the requirements of the International Energy Conservation Code (IECC), the most commonly adopted model energy code in the U.S. for residential buildings. To meet IECC’s U-factor and solar heat gain coefficient (SHGC) requirements insulating double-pane windows with low-emissivity (low-e) coatings are often used.

Videos:

Additional Links:

http://www.greenbuildingadvisor.com/blogs/dept/musings/window-reflections-can-melt-vinyl-siding

http://www.nachi.org/low-e-windows.htm

http://blog.archpaper.com/wordpress/archives/8386

Reports:

E windows LBNL-5022E

E windows 020410-NAHB+Study

If you have had and fires or incidents involving Low -E Windows and Vinyl Siding? I would love to hear from you. Please email me @greenmaltese@gmail.com

A special thanks to Chief Kevin A. Gallagher for bringing this issue to my attention.

Stay Safe

Lt. John Shafer

 

1 Comment

  • Sergio Hunt says:

    Initially I had certain misconceptions regarding the impact of sunlight on the energy efficient windows, but this article has helped me to clear out those concerns. You can check out the Keller sliding doors that we supply which is highly energy efficient.

Leave a Reply

Your email address will not be published. Required fields are marked *

background image Blogger Img

John Shafer

An 18 year veteran of  the fire service, and currently a Lieutenant and the Training Officer for the Greencastle Fire Department.  An Indiana regionally recognized instructor on building construction, fireground search and command management, he has traveled throughout the State of Indiana delivering specialized training programs on building construction, fireground search and firefighter safety.
Comments
John Shafer
Fire Safety Challenges of Green Buildings Report
I you have questions you can email me at greenmaltese@gmail.com Thanks John Shafer
2014-09-01 17:41:22
sandeep
Fire Safety Challenges of Green Buildings Report
i am doing bachelors degree in bulding technologies in final year currently iam doing my project "fire fighting systems for green buildings" so i need your valuble guidence and references.iam very thankful to you if you can do....
2014-09-01 16:26:36
Another Spray Polyurethane Foam (SPF) Attic Fire | Green Maltese
Spray Foam Basics for the Fire Service
[…] in September I wrote a post to raise awareness of Spray Polyurethane Foam (SPF) for the fire service. In this article I […]
2014-07-27 00:20:14
Shan Raffel
Going Interior? Keep the door closed until you make the push!
Nicely analysed John. Notice at 3.02 that the flame issuing from the front windows was right down to the bottom of the opening indicating that these were all functioning as exhaust outlets. Which means that there must be other openings that are serving as the inlets on side B,C,D. The front door showed a bi-directional…
2014-07-01 03:12:55
Sergio Hunt
Energy Efficient Windows Can Melt Vinyl Siding
Initially I had certain misconceptions regarding the impact of sunlight on the energy efficient windows, but this article has helped me to clear out those concerns. You can check out the Keller sliding doors that we supply which is highly energy efficient.
2014-06-02 11:01:20

John Shafer's Discussions


Follow John Shafer

FireEMS Blogs eNewsletter

Sign-up to receive our free monthly eNewsletter

LATEST FIREFIGHTER NEWS

HOT FORUM DISCUSSIONS

LATEST ON FIRE ENGINEERING

FEATURED DISCUSSIONS