Hi, I am not an architecht but an engineer in the process of doing some thermal building analysis thus learning some architectural things on the go.
I would like to calculate the area of the shadow projected over the window of the respective solar protections, with ECOTECT. I would use this information to calculate an external shadow coefficient to be used in local regulation calculations for a thermal ordinance. Just for information the equation is:
CSEt = (IBFt ((AAB - ASVt) / AAB) + (IDFt + IRFt)) / ITFt
where:
-CSEt is the value of the external shadow coefficient for an specific facade of a window at time (t)
-IBFt direct irradiation at time t, over the facade where the window is (W/m2)
-ASVt the area of shadow projected by the solar protection in (m2) at time t.
-AAB area of the window (m2).
-IDFt diffuse solar irradiation at time t, over the the facade where the window is (W/m2)
-IRFt reflected irradiation at time t, over the facade where the window is (W/m2)
-ITFt total irradiation at time t, over the facade where the window is (W/m2)
All the irradiation data is given in the calculation details (for each facade orientation N,NE,S...), thus I would like to calculate ASVt (area of shadow projected).
I also have the solar declination, equation of time and legal times of maximum solar gains for each orientation along with the coordinated from the city for the specific critical days of the year to be evaluated.
Given that I have most data, I would like to know how to calculate the area of shadow projected by the solar protection using ECOTECT. My guess is to project the shadow under the specific conditions (date and time) and trace the projection over a vertical plane (just over the window) and then measure its area? Is this possible (haven't done it yet), would this be a good approximation or is there a more direct way?
Cheers,
Timo
Shadow Area
Hello Timo,
Yes, ECOTECT is able to calculate the area of the shadow on your glazing at a particular time.
One way I would do this is first select your window object and define your time of the day. Then use the Calculate Sun-Path Diagram to calculate the shading mask of the window.
This process will give you some good information on the shading of your window (try the "show shading coefficient" button), but the feature you are looking for is the percent shading. Once the % shading is displayed on the sunpath diagram, you can use and move the current sun position by dragging it, or more accurately, using the left and right for the time, and up and down arrow for the date. Use the Ctrl+ arrows to move per minutes and days for even more accuracy.
Once you have you % shading at the time you are interested, it is just a matter of multiplying this value by the area of your glazing to get the area of shading on the glazing. Note that the software assume the center of the selected object for the sunpath diagram.
Another option would be to create a smal script asking ECOTECT and compute the shadow area for you.
I hope this help. I am sure there is at least another way to go about this, but this is the one that comes to mind.
Best,
Olivier
Thanks, Oliver This has
Thanks, Oliver
This has worked fine for my purpose!!
I hope to be able to write scripts in the future to ease the tasks
Thanks,
Timo
Would like to test the script
Hi Timo,
I would appreciate if I could test your script once it is finished as I am working on similar themes.
I am an architect and thus use a simpler approach
I simulate the insolation values with and without shading and by division of shaded through non shaded values derive the 'reduction factor' or shading coefficient.