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

Externally Calculated Renewable Energy as Input to EnergyPlus

asked 2016-09-06 17:39:29 -0500

updated 2016-09-07 14:29:07 -0500

Hi Modeling Community,

I am calculated the amount of electrical and thermal energy collected from a renewable energy system externally to EnergyPlus. I would like to input the amount generated into EnergyPlus' energy balance but I'm not sure how.

Is there an electrical component that can read values from a schedule or actuator that can subtract energy? I found ElectricalLoadCenter:Generators but it seems to be overly complex and the Photovoltaic:Simple also requires specifications of a PV array.

What about a thermal energy input, maybe a heat exchanger or thermal storage tank? Edit: As a point of clarity, the thermal energy would be best added to an HVAC system input to reduce the load on a boiler.

Thank you for your time,


Edit 2: Still looking for a way to add renewable energy or subtract energy from the total building consumption.

Edit 3: Providing a negative value to ElectricEquipment does not appear as though it will work because it returns the below fatal error.

   ** Severe  ** Out of range value Numeric Field#1 (Design Level), value=-456.00000, range={>=0}, in ELECTRICEQUIPMENT=SPACE2-1 ELECEQ NEGATIVE
   ** Severe  ** IP: Out of "range" values found in input
   ** Severe  ** IP: Out of "range" values and/or blank required fields found in input
   **  Fatal  ** IP: Errors occurred on processing IDF file. Preceding condition(s) cause termination.
edit retag flag offensive close merge delete


I've never tried this but can you set a schedule with negative values for an ElectricEquipment object?

Jamie Bull's avatar Jamie Bull  ( 2016-09-07 13:56:22 -0500 )edit

@Jamie Bull I'll give it a try.

JustinShultz's avatar JustinShultz  ( 2016-09-07 14:01:52 -0500 )edit

@Jamie Bull, no luck. I receive a fatal error regarding the Equipment Level being out of bounds. I have edited my question to include the full error message.

JustinShultz's avatar JustinShultz  ( 2016-09-07 14:29:57 -0500 )edit

Ah well. It was a long shot. Another one - how about if you set the negative value in the schedule rather than the design level?

Jamie Bull's avatar Jamie Bull  ( 2016-09-07 16:26:25 -0500 )edit

@Jamie Bull, I gave it a try and receive a very similar error. The schedule is checked for values >=0.0 as well. No luck.

JustinShultz's avatar JustinShultz  ( 2016-09-08 09:35:18 -0500 )edit

4 Answers

Sort by » oldest newest most voted

answered 2016-09-19 13:30:39 -0500

Archmage's avatar

There is an example file called MicroCogeneration.idf that uses the Generator:CombustionTurbine to fake a wind turbine. The performance curves are set up so that it uses no fuel to make the electricity. In that file it is just a flat baseload power production, but the ElectricLoadCenter:Distribution object could be setup to track a prescribed schedule for renewable production.

edit flag offensive delete link more


Apologizes for the delay but I have implemented the solution you provided and found it to work excellently. Thank you for provided a great example to get me started.

JustinShultz's avatar JustinShultz  ( 2016-11-10 15:07:13 -0500 )edit

answered 2016-09-06 18:41:30 -0500

For thermal, take a look at the PlantComponent:TemperatureSource.

edit flag offensive delete link more


Oh yes! I've used this component on a river cooling project but overlooked it for this application. Excellent suggestion, thank you.

JustinShultz's avatar JustinShultz  ( 2016-09-07 09:53:49 -0500 )edit

answered 2016-09-07 16:59:44 -0500

Not sure you necessarily want to go down this path, but you could use, e.g., Photovoltaic:Simple with default inputs and then overwrite its output by using an EMS actuator.

edit flag offensive delete link more


Hello @shorowit, I would absolutely be willing to use an EMS Actuator. The root of my question stems from finding the connectivity points for an ExternalInterface:FunctionMockupImport. However, I'm not sure how I would write an actuator that would overwrite the generated energy. What would the Actuated Component Type and Actuated Component Control Type key words be? Do you have an example of EnergyPlus code that you can share?

JustinShultz's avatar JustinShultz  ( 2016-09-08 09:30:05 -0500 )edit

Hi @shorowit, do you have any examples you can provide or should I start a new question to see if others can provide assistance? Thank you for your time.

JustinShultz's avatar JustinShultz  ( 2016-09-09 11:42:44 -0500 )edit

I don't offhand. Maybe @Archmage can chime in with some guidance.

shorowit's avatar shorowit  ( 2016-09-09 12:11:59 -0500 )edit

answered 2016-09-06 18:22:54 -0500

Hi Justin,

I will suggest to consider the OtherEquipment object in E+:



edit flag offensive delete link more



So how would this work with an electric energy source generated by a renewable system? I'm assuming the Fraction Lost field would be set to 0, but if that was the case I would not expect this configuration to affect the results.

MatthewSteen's avatar MatthewSteen  ( 2016-09-06 19:13:52 -0500 )edit


Other Equipment object is provided as an additional source for heat gains or losses directly to the zone. That is to say, a loss can be entered by putting a negative value into the Design Level field(s). Note, too, that this object does not have an end-use component – gains or losses do not show up in the bottom energy lines (except as influencing overall zone gains or losses).

MatthewSteen's avatar MatthewSteen  ( 2016-09-06 19:14:11 -0500 )edit

Hi Thierry, thank you for your answer. I believe @MatthewSteen is correct, I've used OtherEquipment to add or subtract heating to a zone but I'm looking more specifically how to subtract electrical energy from the building. Additionally, the thermal energy would be best added to an HVAC system, not the zone directly.

JustinShultz's avatar JustinShultz  ( 2016-09-07 09:33:25 -0500 )edit

You are both right. I had heating/cooling in mind.

Thierry Nouidui's avatar Thierry Nouidui  ( 2016-09-07 09:53:44 -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

1 follower


Asked: 2016-09-06 17:39:29 -0500

Seen: 536 times

Last updated: Sep 19 '16