Windows and climate

The efficiency of a window, door or skylight can't be considered in abstract. Weather conditions should be taken into account. Different climates demand windows with different charactheristics, namely expressed in terms of unwanted heat losses (U-Factor) and unwanted heat gains (SHGC)... 

Climate & Window Glasses

In cold climates it's particularly important to use low-E coating glasses to reduce heat losses through the windows.

In hot climates the most important is to use Low E2 glasses to limit solar heat gains (low-E2 glasses are particular efficient in reducing the infrared and some ultraviolet rays, besides being good insulators and transmitters of visible light).

See also: Window Glasses and Panes

Better yet, it's convenient to consider different types of windows to mixed climate conditions, that is, to different climate zones.

USA Four climate zones for Windows

In USA, Energy Star considers four climate zones for qualified windows, doors, and skylights:

Northern: colder climates, demanding mostly heating windows
North/Central: temperate mixed climates
South/Central: temperate mixed climates
Southern: warmer climates, demanding mostly cooling windows

Windows and Energy Star US Climate Zones

Source: www.energystar.gov

See also: Detailed State US table with climate zones for windows, doors and skylights

The U-factor values and the SHGC in those four American climate zones are the following, for windows:

Northern climate: U-factor: <0,35; SHGC: any
North-Central climate: U-factor: <0,40; SHGC: <0,55
South-Central climate: U-factor: <0,40; SHGC: <0,40
Northern climate: U-factor: <0,65; SHGC: <0,40

Energy Star Climate Zones for Skylights

Northern climate: U-factor: <0,60; SHGC: any
North-Central climate: U-factor: <0,60; SHGC: <0,40
South-Central climate: U-factor: <0,60; SHGC: <0,40
Northern climate: U-factor: <0,75; SHGC: <0,40

 

Windows and Australia Climate Zones

AUSTRALIA
Climate Zones for Windows

Image Source: www.greenhouse.gov.au

Australian Window Energy Rating Scheme (WERS) considers three large Australian climate zones. Windows are rated from 0 to 5 stars for both cooling (summer) and heating (winter).

 

Windows and Canada Climate Zones

 

CANADA
Climate Zones

Canadian authorities also consider four different types of climates and qualified windows, doors and skylights.

 

 

 

US climate Zones
for Windows, Doors and Skylights

TYPE OF WINDOWS, DOORS AND SKYLIGHTS
State Climate Zone Window
Alabama South/Central or Southern
Alaska Northern
Arizona Northern or South/Central
Arkansas South/Central
California South/Central
Colorado Northern or North/Central
Connecticut Northern
District of Columbia North/Central
Delaware North/Central
Florida Southern
Georgia South/Central or Southern
Hawaii Southern
Iowa Northern
Idaho Northern
Illinois Northern or North/Central
Indiana Northern or North/Central
Kansas Northern or North/Central
Louisiana Southern or South/Central
Kentucky North/Central
Maryland Northern or North/Central
Massachusetts Northern
Maine Northern
Michigan Northern
Minnesota Northern
Mississipi South/Central or Southern
Missouri Northern or North/Central
Montana Northern
Nevada Northern or South/Central
New Jersey Northern or North/Central
New Mexico North/Central or Northern
North Carolina North/Central or South/Central
North Dakota Northern
Nebraska Northern
New Hampshire Northern
New York Northern
Ohio Northern or North Central
Oklahoma South/Central
Oregon Northern
Pennsylvania Northern
Rhode Island Northern
South Carolina South/Central
South Dakota Northern
Tennessee North/Central or South/Central
Texas South Central or Southern
Utah Northern or South/Central
Vermont Northern
Virginia North/Central
Washington Northern
West Virginia Northern or North/Central
Wisconsin Northern
Wyoming Northern

See also: