Alaska Log Building Construction Guide: Building Energy-Efficient, Quality Log Structures in Alaska by Michael Musick

Author:Michael Musick [Musick, Michael]
Language: eng
Format: azw3
Publisher: Prepper Press
Published: 2017-03-11T05:00:00+00:00

2.6 Windows, Doors, and Skylights

Windows, doors, and skylights affect heat loss more than any other element of a building’s thermal envelope. For example, windows can account for as much as 25 percent of the total envelope conductive heat loss, although they generally account for only 3 to 5 percent of the total envelope area. A common double-glazed window loses 10 times more heat per square foot than a 2x6 insulated wall.

Window, door, and skylight requirements will be reviewed in two years and modifications will be made as necessary to improve this standard. The following requirements apply to a window, door, or skylight:

a. A product performance claim referencing a test conducted after December 31, 1994 shall be acceptable only if testing was performed using the protocols specified by the National Fenestration Rating Council (NFRC, 962 Wayne Avenue, Suite 750, Silver Springs, MD 20910). Such a test shall be conducted by an independent laboratory certified by NFRC to perform such a test. The test report shall include a statement that the test was performed in accordance with NFRC protocols.

A product performance claim referencing a test conducted under the AAMA 1503.1-80, AAMA 1503.1-88, ASTM C236-80, or ASTM C236-87 test method prior to January 1, 1995 shall be acceptable. Thereafter, only a performance test conducted under the NFRC protocols shall be acceptable. In addition, the following restrictions apply to the AAMA test methods.

1. Standard test size for residential windows shall be:

Window Type Width by Height (inches)

Horizontal sliding 60 by 36

All other 36 by 48

2. A window test sample shall be of a production line size closest to the model size stated above.

b. A sample used for testing shall be a production line unit or representative of a unit commonly manufactured. No adjustment shall be made to a unit to prepare it for testing than would ordinarily be made in the field by a builder.

c. A laboratory test report showing all relevant product performance values shall be submitted to the Alaska Housing Finance Corporation, Research Information Center, 4300 Boniface Parkway, Anchorage, AK 99504. Telephone: (907) 338-6100 or (800) 478-INFO (478-4636) within Alaska. A manufacturer’s literature is NOT an acceptable substitution for a laboratory test report. A report will be available for public inspection to allow consumers to verify performance claims.

d. A hollow core wood door or a single-glazed window or skylight in the thermal envelope is not allowed regardless of which method (chapter 3, 4, 5, or 6) is used to comply with this Standard.

e. A metal frame for a window, skylight, or threshold shall have a continuous thermal break between inside and outside metal surfaces.

f. A window, door, or skylight whose performance is not documented by a test report shall be given a default R-value as follows:

Product Default R-Value

double-glazed window or skylight 1.7

triple-glazed window or skylight 2.5

insulated metal door 5.0

solid core wood door 2.5

door with glazing 1.7

g. Air infiltration shall be limited to the following maximums:

1. Operable Window:

casement: 0.10 cubic feet per minute per linear foot of operable sash crack; awning/projecting: 0.15 cubic feet per minute per linear foot of operable sash crack; sliding/double hung: 0.

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