HOW TO USE THE OVERHANG ANNUAL ANALYSIS SHADING CALCULATOR

The general question addressed by overhang annual analysis is: to what extent is a window shaded by an overhang each hour of the day during each month of the year? 

With this information, an architect, designer, builder, or home owner can design a window system that admits sunlight when it is desirable and provides shade when it is not.

The basic output of the program is a chart showing the degree to which the overhang is shading the window, for each hour of the day, for each month of the year. The entire year is depicted, so you can rapidly assess the overhang's performance on an annual basis, and modify the inputs to achieve the optimum design. For instance, if the overhang is providing insufficient shade, you can make it deeper or reduce its distance above the window.

Note that this tool is used for vertical windows only, and it assumes that the overhang extends far enough to the side of the window to shade it even when the sun is off to the side (see the FAQ page for more information).

Inputs
The inputs vary based on the type of overhang being analyzed: horizontal or pitched (titlted). If you change the "overhang style" input, you'll see a different diagram and different overhang inputs to the right.

For specific instructions on any input, click on its name.

Outputs
To perform the calculation, set the inputs to the appropriate values and click the "Calculate" button. The output table will refresh. Every time you modify the inputs, click the "Calculate" button again to see the refreshed results.

The output table has a row for each month, and a column for each hour. The colour of the cell indicates the fraction of the window area that the overhang is shading at that time on the 15th day of that month. A black cell means that the window is totally shaded. A white cell means that the window is entirely unshaded. Gray cells indicate the degree of partial shading. A blank white cell indicates that the sun is below the horizon. A yellow cell indicates that the sun is above the horizon, but not shining on the window.