How to Locate Windows for Optimal Shading
hughsdb
| Posted in Green Building Techniques on
When we design new homes, we do shading studies of every window. This tells us the lowest point on any given wall that we will allow the bottom of a window to go. The variables are the day of the year, time of day, and width of the overhang. To this point we have had done this we have done this as a hip shot. How what would be involved in a more scientific approach?
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The only way to do it is to set up your shading in an energy modeling software.
I've done this in HOT2000, a bit of a steep initial learning curve but pretty easy to make changes once the model is up and running. The overhangs are a bit limited in the software since they can only go along the top of a window and can't specify width or offset from window center line.
Keep in mind that most modeling software doesn't handle overheating all that well, this is something you need to manual check for if you have a lot of glazing.
The overhangs I settled on were best for all year around efficiency but have too much solar gain in the fall, this means I need to run the AC about a month longer, which costs much more than the extra bit of heat I gain in the winter. Something that was not directly obvious from the energy models.