EnergyPlus

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  1. Spend several development cycles squashing long-standing bugs and paying off any tech. debt

    Lots of great new features and capabilities have been made available with E+ over the years, but there are still many lingering bugs that seem to pop up unexpectedly. When these bugs pop up, there is a detrimental effect on project timelines and our ability to rely on E+ to do the heavy engineering lifting.

    A good example is plant pumping systems; seems like the same types of issues are being reported by a number of users over the last year.
    https://github.com/NREL/EnergyPlus/issues/5892

    Also there appear to be some issues with sizing that get reported a lot; HW coils sizing to…

    15 votes
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    6 comments  ·  Other  ·  Admin →

    Thank you for the suggestion! Planning for EnergyPlus development cycles is often a balance of prioritizing:

    - new features,
    - bug fixes (short term fixes),
    - structural improvements to the code base (long term fixes),
    - performance improvements (i.e., make EnergyPlus faster), and
    - other usability improvements

    The team will take your suggestion to focus more on the priorities beyond new features into consideration.

  2. Link Kiva ground heat transfer model to low temperature radiant model

    The recently added Kiva ground heat transfer model can be used to perform detailed ground heat transfer from basements and slab-on-grade floors. Currently there is no method in EnergyPlus for estimating the heat loss to ground from slab-on-grade radiant floors. In this proposed task the ground heat transfer model Kiva would be linked to the low temperature zonal radiant floor model. Research has shown that heat loss from slab-on-grade radiant floors can be significant and should be accounted for when modelling these types of systems.

    6 votes
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  3. One DX coil object to rule them all

    Problem: There are several coil object types that represent DX heating or cooling with different input fields, capabilities, and source code.

    Rationale: Providing a single, generalized DX coil for both heating and cooling with all capabilities will enforce consistency.

    Solution: Create a single DX cooling coil that covers:

    - Coil:Cooling:DX:VariableRefrigerantFlow
    - Coil:Cooling:DX:VariableRefrigerantFlow:FluidTemperatureControl
    - Coil:Cooling:DX:SingleSpeed
    - Coil:Cooling:DX:TwoSpeed
    - Coil:Cooling:DX:TwoStageWithHumidityControlMode
    - Coil:Cooling:DX:MultiSpeed
    - Coil:Cooling:DX:VariableSpeed
    - CoilPerformance:DX:Cooling
    - Coil:Cooling:WaterToAirHeatPump:ParameterEstimation
    - Coil:Cooling:WaterToAirHeatPump:EquationFit
    - Coil:Cooling:WaterToAirHeatPump:VariableSpeedEquationFit

    and the equivalent coils for a single DX heating coil.

    5 votes
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  4. Add PVWatts as a Generator:Photovoltaic

    The PV systems in EnergyPlus are inadequate for most common applications, specifically residential PV. PVWatts is the defacto standard for PV calculations outside EnergyPlus. That calculation should be included as an option in EnergyPlus.

    8 votes
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  5. Model a chiller with multiple compressors

    Model a chiller with multiple compressor

    8 votes
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    1 comment  ·  HVAC - Plant  ·  Admin →
  6. Output in HDF5

    Right now EnergyPlus outputs the hourly/timestep variables and meters to eio and/or sqlite. Then, the eio can be translated into csv. Both have some issues:

    eio -> csv is buggy and the csv cannot always be read. Additionally there's an inherent loss in precision when serializing to text-based formats.

    The other option, SQLite, solves some of those problems, but can be really slow to read large output files.

    I propose having an option to output in HDF5, which is a cross-platform binary tabular data format used extensively in high performance computing applications. I/O is very fast and there is no…

    5 votes
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    in discussion  ·  2 comments  ·  Output  ·  Admin →
  7. Reuse shading calculations between runs

    Shading calculations are processing intensive and can take a long time for large models with a lot of shading surfaces.

    Once all design decisions for the geometry and envelope properties of a building are made, the effect of shading on the building should be identical between simulations (valid assumption?).

    If EnergyPlus could reuse these calculations between runs, a lot of processing time could be saved. Of course, EnergyPlus would have to detect that geometry and envelope have changed to force a recalculation.

    29 votes
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  8. Water cooled condenser for DX coils

    DX cooling coils currently have options for air-cooled and evaporatively cooled condenser. This would add water cooled as an option. Some users use the water-to-air heat pump coil (Coil:Cooling:WaterToAirHeatPump:EquationFit) to model this, but this cannot be used in every type of system, and is not as convenient to use.

    8 votes
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  9. GSHP sizing

    GSHP sizing is currently not available.

    8 votes
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  10. Warm Start from Saved State

    Problem: Some applications of EnergyPlus for building operations would benefit from being able to restart from a state saved during a previous run of the same building. Currently EnergyPlus initializes loads at 23C and system nodes at 5C and then conducts a number of warm up days for transient conditioning. The runtime burden of those warm up days can be significant for some applications.

    Rationale: Increased performance (speed) for model predictive control that uses EnergyPlus in the control loop.

    Solution: Users could direct the program to save state at some point during the simulation and halt. The program could be…

    17 votes
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    in discussion  ·  4 comments  ·  Other  ·  Admin →
  11. EnergyPlus for Dummies

    Update the GettingStarted documentation to help new EnergyPlus users really understand what EnergyPlus is all about and how to start becoming productive energy modelers using EnergyPlus. Assume that the readers of the GettingStarted documentation do not know anything about modeling. It would assume nothing about the user and walk them through the process introducing a bunch of different concepts at simple level. It would build off the approach used in GettingStarted but would be enhanced with addressing the many issues that we know that new users have when starting with EnergyPlus. It would also include a links on how to…

    7 votes
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  12. On/Off thermostat

    Problem: HAVC system is not simulated based on real operation conditions with part load performance in a small time step

    Rationale: HVAC system operation may not turn on and off very quickly in a small time step based on system configuration. For example, the system configuration requires HVAC system to turn on with a minimum operation time. When it is off, it requires minimum off time period. The existing E+ simulates HVAC system operation based on load only, so that the system operates at part load condition only and the operation is unable to be simulated realistically.

    Solution: Create a…

    7 votes
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    in discussion  ·  1 comment  ·  Control  ·  Admin →
  13. Add support for ASHRAE Standard 205 data representations

    Problem: Curve fits of manufacturer data are onerous and error prone.

    Rationale: Using standard data representations that are generated by manufacturers and read directly into EnergyPlus will eliminate substantial effort on behalf of energy modelers.

    Solution: ASHRAE Standard 205 defines such data representations (currently for liquid cooled chillers, unitary air conditioning equipment (i.e. DX cooling coils), and fan assemblies. Routines to read Standard 205 data and simulate the respective equipment should be added to EnergyPlus.

    Context: Read Standard 205 title, purpose and scope here: https://www.ashrae.org/standards-research--technology/standards--guidelines/titles-purposes-and-scopes#SPC205P

    Pros and Cons:
    + less work for modelers
    + standard data models lend themselves to…

    4 votes
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    in discussion  ·  0 comments  ·  Input  ·  Admin →
  14. Additional Daylighting Flexibilty

    Currently, a project to allow for more reference points is underway but during the development of that project a number of additional capabilities were suggested to increase the flexibility of the daylighting model in EnergyPlus even further. The following is a list of possible enhancements:

    • Associate one or more individual Lights objects with each Daylighting:Controls object

    • Allow multiple Daylighting:Controls objects per zone

    • Separate the daylighting zones from thermal zones since they do not always align (i.e. allow the control of daylighting in one thermal zone be based on reference point in another thermal zone)

    • Allow a…

    4 votes
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    2 comments  ·  Daylighting  ·  Admin →
  15. Run-Around Heat Recovery System

    Problem: EnergyPlus cannot model run-around heat recovery systems.

    Rationale: A run-around system can reduce peak heating and cooling loads as well as total heating and cooling loads. EnergyPlus already has models for all the underlying pieces and it makes sense to finish out what is needed so that the air loop and plant can handle such configurations.

    Solution: Add whatever is needed to allow setting up a plant model with just two or more coils and a pump. Allow coils in air loop to run wild without a Controller:WaterCoil. Allow coils for run-around to be located virtually anywhere in the…

    12 votes
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  16. Add option to disable self-shading

    LEED grants credit for self-shading, but to obtain this credit you need to model a baseline building that is shaded by adjacent structures, but not by itself (if I interpret correctly)! It doesn't seem possible to back out this data point using multiple runs, rather direct switch inside EnergyPlus is needed. Here is a relevant unmethours discussion. https://unmethours.com/question/3871/shading-by-adjacent-structures-not-possible-in-leed-baseline-and-e/

    4 votes
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    in discussion  ·  1 comment  ·  Geometry  ·  Admin →
  17. Air Source Central Plant Electric or Gas Engine-Driven Heat Pump

    Problem: EnergyPlus cannot model a heat pump in the central plant supplying (alternatively) cooling to a chilled water loop or heating to a hot water loop. This is an air to water heat pump.

    Rationale: Though not as common in the US, in other parts of the world air to water heat pumps for heating are used and EnergyPlus should be able to model them..

    Solution: Add a new component model to EnergyPlus plant for such equipment.

    Context: Current work around is to use a heat pump water heater, which is really inteded for domestic hot water, along with an…

    9 votes
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  18. Add Life Cycle Assessment/Embodied Energy to EnergyPlus

    Add the capability to EnergyPlus to compute the embodied energy of the building being modeled and perform a life-cycle assessment for the building.

    https://en.wikipedia.org/wiki/Embodied_energy

    https://en.wikipedia.org/wiki/Life-cycle_assessment

    This would primarily be adding inputs to associate building materials used with the building with factors to associate the embodied energy as well as additional reporting.

    6 votes
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    in discussion  ·  7 comments  ·  Other  ·  Admin →
  19. Window Constructions with Up to 10 Glazing Layers

    Problem: Windows can have more than 4 glazing layers. EnergyPlus currently limits the number of glazing layers to be 4 or less.

    Rationale: New window technologies can have more glazing layers. BIM data may arrive with more than 4 layers and it is difficult to translate to an equivalent window.

    Solution: Allow Construction objects to specify up to 10 WindowMaterial:Glazing objects. Improve code of the Window module to allow more than 4 glazing layers.

    Context: The LBNL Window tool allows up to 10 glazing layers. EnergyPlus model is similar but allows only 4 glazing layers (in the regular/legacy layer-by-layer window…

    3 votes
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    in discussion  ·  0 comments  ·  Envelope  ·  Admin →
  20. IDF Editor for MAC

    I am a Mac user and I had to install a windows partition in my computer to have Energy Plus IDF Editor running. This is the only program I run on Windows.

    Once Energy Plus important part of my research, having a mac native IDF Editor can help a lot!

    Otherwise, when a program is launched for more than one platform it is quite polite to offer them equally functional.

    I am very respectful about the hard work needed to design and offer free programs. But I`m very hopeful that an IDF editor for mac can be offered soon.

    Thanks

    14 votes
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