Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

E+ EMS based on timesteps

asked 2016-02-05 19:17:04 -0500

Alex Vlachokostas's avatar

updated 2016-10-21 12:29:52 -0500

Hi everyone,

  • The fact:

I have simulated 25 different light-redirecting glazings (BSDFs) in Radiance. After post-processing the results I know for a specific time of the day which light-redirecting glazing is the best in terms of good illuminance levels and minimum glare for the occupant. Essentially, I have a file with 2 columns. Column 1 has the hourly timestep for a year (rows: 1 to 8760) and column 2 has the name code of the optimal light-redirecting glazing (e.g., Window_i) in terms of illuminance and glare for each timestep.

  • The question:

Which variable do I use in E+ EMS in order to call a different WindowMaterial:Glazing object for every timestep of the E+ simulation? For example, in a 'high-level' way it might look like a 8760 times loop that would read each line of the aforementioned column 2:

IF timestep = 8, SET WindowMaterial:Glazing, Window_1, ENDIF;

Thank you.

edit retag flag offensive close merge delete


How did you obtain the BSDFs for the different glazings? I have found this to be a problem. The manufacturers I have contacted haven't been able to provide the BSDF information.

Chris Jones's avatar Chris Jones  ( 2016-02-08 08:15:36 -0500 )edit

You can obtain the BSDF in WINDOW (software from LBNL- link text). You can put together layers of different glass typologies that are available in the software's database and then you calculate the BSDF XML file that you can use at your E+ simulations. This is how you do it: Ref: link text (focus on the "Generating BSDF XML" files).

You can do the same in Radiance (Ref: link text) but, in my opinion, the degree of difficulty is much higher.

Alex Vlachokostas's avatar Alex Vlachokostas  ( 2016-02-08 10:02:58 -0500 )edit

1 Answer

Sort by ยป oldest newest most voted

answered 2016-02-05 22:28:31 -0500

Chandan Sharma's avatar

EMSThermochromicWindow.idf provides a good starting point here. EMS program should determine hour of simulation (1-8760) using the built-in variables (DayOfYear and CurrentTime/Hour may be particularly useful), and appropriate window construction should be chosen.

edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Training Workshops


Question Tools



Asked: 2016-02-05 19:17:04 -0500

Seen: 268 times

Last updated: Feb 05 '16