This tool lets you visualise the degree to which a horizontal overhang shades a window throughout the year. It can also be used to calculate the solar power incident on the window, relative to full, direct sun.
Please read the important instructions, notes, and FAQ pages before using this tool.
Please enter your geographical latitude in decimal notation, such as "42.5" (don't include the quotation marks in the input field). The value should be between 0 and 90 degrees, although horizontal overhangs are typically only effective for temperate latitudes (24 to 60 degrees).
Use the North/South drop-down menu to indicate North or South Hemisphere.
(use the "what's here?" option to display coordinates)
This is the direction that the window faces (true direction, not the direction inidcated by a compass). You can select one of the eight cardinal directions (North, Northeast, etc.), or 10-degree increments in between.
For example, "10° E of S" means a window that faces 10 degrees East (i.e. counterclockwise) of due South.
By default, the analysis depicts the shading by the darkness of the data cells, but you can select to have the numerical percentage of sun or percentage of shade listed as well.
Sun %Each data cell has the percentage of sun listed, in addition to the background color as an indicator. The Sun % is in 1% increments. A value of "73%", for example, indicates that the overhang is shading about 27% of the window area, and 73% of the window is in the sun.
Shade %Each data cell has the percentage of shade listed, in addition to the background color as an indicator. The Shade % is in 1% increments. A value of "69%", for example, indicates that the overhang is shading about 69% of the window area, and 31% of the window is in the sun.
Power %Each data cell has a percentage representing the magnitude of insolation received compared to the insolation that would received with no shading and with the sun normal to (i.e., directly in front of) the window. This is the same as the Sun % above, but it also takes into account the angle of the sun compared to the orientation of the window, with power effectively decreasing as the sun illuminates the window at more shallow angles (in other words, power decreases as the window presents a smaller cross-section to the sun). The background color represents the percentage of power, with lighter cells indicating higher power.
Power % (with glass)The same as the previous option, but the reflectivity of the window glass is also taken into account: glass transmits about 95% of the energy in sunlight when the sun is normal to the glass surface, but transmission drops off steeply when the sun's angle of incidence drops below about 45 degrees. The background color represents the percentage of power, with lighter cells indicating higher power.
Whether the calculation is to be performed for a horizontal overhang, whose position can be described by its height above the window and extension from the facade, or a pitched overhang, which may be roof eaves, or a separate structure attached to the building at an angle.
When you change this input, the overhang graphic to the right will change to allow you to enter different measurements for the overhang style you selected.
This is the distance that the overhang extends from the wall. Measure from the outermost tip of the overhang straight to the wall.
You can use any units for the overhang depth — millimetres, centimetres, metres, etc. — as long as you use the same units for all window and overhang measurements.
This is the vertical distance between the top of the window glass and the bottom-most edge of the overhang.
You can use any units for the overhang spacing — millimetres, centimetres, metres, etc. — as long as you use the same units for all window and overhang measurements.
This is the height of the glass portion of the window (don't include the frame).
The distance of the window above the ground doesn't matter.
You can use any units for the window height — millimetres, centimetres, metres, etc. — as long as you use the same units for all window and overhang measurements.
Invercargill
Auckland