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

I want a site with constant temperature and 0 solar radiation how to edit weather files

asked 2016-10-11 07:25:00 -0500

updated 2017-05-29 09:32:28 -0500

I try weather data analysis but when i want to convert my edited csv file back to epw it says unknown source and the program terminates

edit retag flag offensive close merge delete

2 Answers

Sort by ยป oldest newest most voted

answered 2016-10-11 12:33:35 -0500

This question has come up often in previous posts.

You can use the free program Elements to adjust weather files.

For your specific application, it seems like it would be easier to just set all of your exterior surfaces to "ground" adjacency, and then specify a ground temperature (changing one number in the .epw file).
If you want to specify the surface heat transfer properties in more detail, see the response to this question.

edit flag offensive delete link more

answered 2016-10-12 18:00:36 -0500

Ivan Korolija's avatar

The other approach could be to use EMS (also supported by DesignBuilder) in order to override weather parameters instead of changing a weather file. Choose environment-related actuators for outdoor dry bulb temperature and solar radiation (direct and diffuse) and change their values at the beginning of each timestep. The attached example changes direct and diffuse solar radiation to 0 and sets the outdoor dry bulb temperature to 18C.

! Weather file outdoor air dry bulb temperature
    oDBT,               !- Name
    Environment,             !- Actuated Component Unique Name
    Weather Data,            !- Actuated Component Type
    Outdoor Dry Bulb;              !- Actuated Component Control Type

! Weather file diffuse solar radiation
    oDifSolar,               !- Name
    Environment,             !- Actuated Component Unique Name
    Weather Data,            !- Actuated Component Type
    Diffuse Solar;              !- Actuated Component Control Type

! Weather file direct solar radiation
    oDirSolar,               !- Name
    Environment,             !- Actuated Component Unique Name
    Weather Data,            !- Actuated Component Type
    Direct Solar;              !- Actuated Component Control Type

! EMS program calling point
    OverrideWeatherData,       !- Name
    BeginTimestepBeforePredictor,  !- EnergyPlus Model Calling Point
    OverrideProg;           !- Program Name 1

!EMS program which sets selected weather parameters to 0
    OverrideProg,           !- Name
    SET oDBT = 18,
    SET oDifSolar = 0,
    SET oDirSolar = 0;
edit flag offensive delete link more


Hi Ivan, I found this answer to be very helpful for a problem I'm working on. I was wondering how one could apply the actuated condition like the one outlined in your answer to just one surface instead of all surfaces? Do I change the boundary condition of the surface or change a parameter of the actuators?

JustinShultz's avatar JustinShultz  ( 2016-10-17 13:42:14 -0500 )edit

Hi Justin, You'll need to create an actuator for each surface you would like to change boundary condition. Boundary conditions can be various such as "Surface Convection Heat Transfer Coefficient", "Outdoor Air Wind Speed", etc. For example if you would like to set outdoor dry bulb temperature for a surface named "WALL" an actuator should be:

    oDBT_wall, !- Name
    WALL, !- Actuated Component Unique Name
    Surface, !- Actuated Component Type
    Outdoor Air Drybulb Temperature; !- Actuated Component Control Type
Ivan Korolija's avatar Ivan Korolija  ( 2016-10-17 14:26:32 -0500 )edit

@Ivan Korolija, thank you so very much! I've been struggling to figure this out for a few weeks. I also rediscovered the EMS Verbose command to find a number of other Actuator variables. I have one remaining question. I have found how to control the air temperature adjacent but I don't see any variables on how to control the solar radiation on a wall. Is there a way to actuate solar radiation for a single wall/window? Thank you again for all your help.

JustinShultz's avatar JustinShultz  ( 2016-10-17 16:08:00 -0500 )edit

@JustinShultz, Solar radiation on a wall (which is automatically applied to any window on that wall) can be switched off completely by setting the 'Sun Exposure' to 'NoSun' in a BuildingSurface:Detailed object. I am not sure you can override solar radiation through EMS for an individual wall/window.

Ivan Korolija's avatar Ivan Korolija  ( 2016-10-17 16:45:06 -0500 )edit

Hi @Ivan Korolija, thank you again for your answer! I have been trying to solve these two questions for quite some time, you have helped me tremendously. Thank you!

JustinShultz's avatar JustinShultz  ( 2016-10-18 13:35:43 -0500 )edit

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: 2016-10-11 07:25:00 -0500

Seen: 644 times

Last updated: Oct 12 '16