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What are the requirements objects to run on EnergyPlus?

asked 2021-07-12 02:00:54 -0500

fahadnajed gravatar image

Hi! I'm a student, currently learning EnergyPlus as a beginner/newbie.

I was thinking that what are the requirements objects to run on EnergyPlus? I see the ExampleFiles under EnergyPlus folder, for example on Minimal.idf, but currently, I'm trying to simulate a basic office building with a specific outdoor and indoor temperature, outdoor and indoor relative humidity, internal gains (lights, people, and equipment), fan and pump efficiency. But I don't know which objects on EnergyPlus I have to input to.

I need to run these specific requirements (sadly I need > 10 points to upload a file) :

Outdoor Temp. (Dry bulb), Outdoor Relative Humidity, Indoor Temp. (Dry bulb), Indoor Relative Humidity, Occupant Density, Sensible Heat Gain / person, Latent Heat Gain / person, Outdoor intake/Introduction, Lighting Power Denisty during AC hours, Lighting Power during None AC hours, % Daylight Area, % Daylight Hours during AC hours, Operating Hour, Plug Load Heat Gain during AC hours, Plug Load Heat Gain during none AC hours, Supply air temperature, Fan Efficiency, Lift during AC Hours, Power Density, Car park during AC Hours, Delta (∆T) Chilled Water Temperature, Delta Condenser Water Temperature, Chilled water pumping efficiency, Condenser water pumping efficiency.

Thank you for reading my question.

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answered 2021-07-13 16:12:01 -0500

sashadf1 gravatar image

Outdoor Temp (Dry bulb) and Outdoor Relative Humidity will both come from the EnergyPlus weather (epw) file you use to run in conjunction with the input data file (idf) used to specify your building systems, materials, geometry, etc.

The indoor dry-bulb temperature/relative humidity are solved for when EnergyPlus is executed: they are not inputs, but rather output variables. You usually don't specify a constant indoor temperature as part of the input. You CAN however, specify HVAC setpoints, which are desired temperature values in the conditioned zone. The HVAC system will, depending on its control scheme, try to output a load to add to the Zone Air Heat Balance in order maintain the setpoint temperature, according to the setpoint schedule and HVAC controls.

Look at the EnergyPlus schedule object documentation to figure out how to specify constant heating and cooling setpoints for the entire year, 24/7, if that is your goal: https://bigladdersoftware.com/epx/doc...

Occupant density and internal gains associated with people come from the People object input: https://bigladdersoftware.com/epx/doc....

There is a field for specifying the nominalnumber of occupants: (https://bigladdersoftware.com/epx/doc...): if you just want to specify directly the number of occupants, use the "People" option for the Field: Number of People Calculation Method.

Note that this is the nominal number of people. The actual occupancy in a thermal zone at any given timestep will be the product of the nominal number of people and the Number of People Schedule value, as specified in this bit of documentation.

https://bigladdersoftware.com/epx/doc...

Sensible Heat Gain / person and Latent Heat Gain / person can be specified using the sensible heat fraction field: https://bigladdersoftware.com/epx/doc....

Normally this field is autocalculated but it can be a user input. "An internal algorithm is used to determine what fraction of the total is sensible and what fraction is latent."

Unsure where to look for Outdoor Intake/Introduction; are you referring to infiltration, natural ventilation, mechanical ventilation, or outdoor air being sucked into the airloop?

See here for the Lights input object: https://bigladdersoftware.com/epx/doc...

For lighting power density (LPD) during AC vs non-AC hours, you will need to have two separate lighting objects in the IDF. "you can use multiple Lights statements for a zone that has two or more general lighting systems that differ in design level, schedule, etc."

Similarly to the people object, you will specify a design/nominal LPD that is multiplied by the schedule value to give the instantaneous LPD at a given timestep. "The electrical input for lighting in a particular timestep is the product of the design level and the value of this schedule in that timestep."

Lighting Power Density (LPD) is defined as watts of lighting per square foot of room floor area (W/sf).

To specify a fixed design/nominal LPD value [W/m^2], use the option Watts/Area in the field Design Level Calculation Method.

https://bigladdersoftware.com ... (more)

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Hi, sashadf1!

Thank you for answering my question sir. Yeah, I also look up on EnergyPlus manual such as InputOutputReference. But I need more details too from professional and experts, like this forum.

Yes, thank you! I'm happy to be part of BEM community (:

fahadnajed gravatar image fahadnajed  ( 2021-07-22 20:04:39 -0500 )edit

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Asked: 2021-07-12 01:59:54 -0500

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Last updated: Jul 22