EnergyPlus

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  1. 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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    1 comment  ·  Output  ·  Admin →
  2. Allow compressor auto-sizing

    THe compressor curves for power and capacity include the rated power and capcity .., and thus no way to “scale” the power or capacity – you need a completely different set of curves for every compressor. Nor is there another way to conveniently determine the needed compressor capacity other than a fairly painful trial and error process. Two of the three projects I’ve worked on were pursuing either a utility incentive for improved efficiency or LEED certification, so an autosized Baseline calculation was required. Trial and error was pretty ugly and time-consuming.

    1 vote
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  3. Add output:variables available for SST or SDT

    Available variables include condensing temperature, evaporating temperature and suction temperature. If I want to confirm the power or capacity of a compressor at a particular timestep, I need the Saturated Suction temp (SST) and Saturated Discharge temp (SDT). It may be the case that these are the same as the condensing and suction temperature output:variables, but that is not clear. I haven’t checked by manual calculation, but that’s because I’m not smart enough about how refrigeration systems work to know whether or not correlation between my calcs and those of E+ was random or not. I can spell “superheat”, but…

    1 vote
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  4. Incorporate economizers, oil coolers of several types, and hot gas defrost of several types

    These design options affect refrigeration system energy performance dramatically, but are not available in E+. e.g., oil coolers can use direct injection or the condenser. Hot gas defrost can be timed or use a liquid drain.

    1 vote
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  5. Standardize scripting between EnergyPlus and OpenStudio

    EnergyPlus and Open Studio team should standardize scripting on a common language. Ruby or Python, please pick one .

    3 votes
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    0 comments  ·  Other  ·  Admin →
  6. 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.

    22 votes
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    4 comments  ·  Performance  ·  Admin →
  7. Improving the capability of EnergyPlus for the development of control algorithms

    I would like to encourage the continued support for the development of the Spawn-of-EnergyPlus (SOEP) simulation platform. Existing EnergyPlus HVAC models fail to capture the dynamic characteristics of components in a realistic way. The idealized control capabilities implemented in EnergyPlus do not reflect reality. To my understanding, the idea behind SOEP is to utilize the Modelica language for modeling HVAC and control systems, and to couple them to EnergyPlus models for envelope heat transfer, lighting and airflow. This approach would leverage the strength of Modelica (modeling dynamic systems) and the growing number of open-source libraries for building applications, with the…

    13 votes
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    0 comments  ·  Control  ·  Admin →
  8. Implement option for external shading calculations

    As stated in the feedback post “Reuse shading calculations between runs”, shading calculations are time consuming for large models with a lot of shading surfaces. In addition, the polygon clipping based algorithms that are used to determine shaded fractions also tends to be unreliable for complex geometry and results in several severe warnings. This limits applicability in shading device design and urban applications or require somewhat awkward workarounds with shading surfaces and transparency schedules such as suggested in this helpserve post (http://energyplus.helpserve.com/Tickets/Ticket/View/9310).

    In computer graphics there are OpenGL based methods (such as: http://www.ibpsa.us/simbuild2012/Papers/SB12_TS09b_3_Jones.pdf) that could drastically speed up shading simulations…

    16 votes
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    0 comments  ·  Geometry  ·  Admin →
  9. Use Kiva to perform foundation heat transfer calculations

    Problem: The current methods of calculating foundation heat transfer are either inaccurate, too slow, too difficult to use, or lack capability to simulate standard foundation designs in the context of a whole-building EnergyPlus simulation.

    Rationale: Heat loss/gain through foundations is becoming a larger part of the envelope load (especially for residential buildings) as codes continue to improve the above-grade envelope.

    Solution: Kiva (http://bigladdersoftware.com/projects/kiva/) is fast, accurate, and highly capable. It offers an easy way to describe the design of the foundations.

    See the New Feature Proposal (NFP) here: https://github.com/NREL/EnergyPlus/blob/kiva/design/FY2017/Kiva-NFP.md

    Please use the GitHub site to comment on the…

    4 votes
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    in progress  ·  0 comments  ·  Envelope  ·  Admin →
  10. Improved Error Message Handling and Documentation

    Error messages (warning, severe, and fatal) are a source of confusion for many users as well as creating problems for interface developers. To improve the error messages, several improvements can be made:

    - An error number could be shown with each unique error message.

    - A new section in the documentation could show the next steps to take to resolve each type of error message. It would be arranged by error number.

    - The format of the error messages could be made more uniform.

    - The text of some error messages could be improved to be clearer

    - Error messages…

    10 votes
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    0 comments  ·  Other  ·  Admin →
  11. 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.

    5 votes
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  12. Add more DX systems types to provide waste heat for reclaim for the Coil:WaterHeating:DesuperHeater object

    Domestic hot water (DHW) is the second largest user of energy in homes today. A water-to-air residential HVAC system with a heat reclaim coil (desuperheater) for DHW can reduce a homes DHW usage by 80%.heat pump. (e.g. ClimateMaster Trilogy 45).

    Currently, the Coil:WaterHeating:DesuperHeater object only supports simple DX cooling coils and can't be connected to any parameter/coefficient estimation DX coil types. Without support for more coil types there is a large shortcoming in EnergyPlus for modeling low-energy homes.

    1 vote
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    0 comments  ·  Other  ·  Admin →
  13. Update LEED Reporting

    The current LEED Summary report helps users working with the LEED forms but it has not been updated much since it was created in 2006. It could be enhanced to provide more information that is needed for LEED submittals. This would help both users of LEED as well as GBCI reviewers. Many more details are needed by USGBC including the information needed for the Energy Performance Calculator and Table 1.4 spreadsheets. In addition, some of the current outputs from the LEED summary report could be revised to be more consistent with the requirements of USGBC.

    9 votes
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    0 comments  ·  Output  ·  Admin →
  14. GSHP sizing

    GSHP sizing is currently not available.

    6 votes
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  15. Integrate Window Calculation Engine

    EnergyPlus currently has three different calculation modules for the detailed calculation of thermal, solar and daylighting properties for fenestration systems:
    1. Original window module implementation (referred as "Winkelmann" here)
    2. Tarcog/BSDF
    3. ASHWAT/EquivalentLayer

    Calculation modules a) Winkelmann and b) Tarcog/BSDF use the same calculation standard (ISO 15099) and for specular systems, they produce very similar results (for surface temperatures and heat flows). The Winkelmann calculation modules include optical calculations for both specular and lambertian, grey body diffuse reflectance of venetian blind slats and woven shade threads. The Tarcog/BSDF calculation module, on the other hand, lacks optical calculations in EnergyPlus and…

    10 votes
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    in design  ·  1 comment  ·  Envelope  ·  Admin →
  16. Water-to-water heat exchanger should be allowed to be on plant demand side

    Water-to-water heat exchanger should be allowed to be on plant demand side. We tried to user this object to model water-cooled economizer with primary-secondary loop. Because the water-to-water heat exchanger currently can only be on the supply size, the inlet temperature is low and cannot capture the savings when the water-side economizer is on the demand side.

    5 votes
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  17. Proportional DCV with user specified Target CO2 concentration

    Currently when using demand controlled ventilation with “ProportionalControlBasedOnDesignOccupancy” or “ProportionalControlBasedonOccupancySchedule”. The target indoor CO2 concentration at design outdoor air flow rate is calculated by equation (15.759) in Engineering Reference Manual.

    It would be great to provide the flexibility to let user directly specify the maximum CO2 concentration value directly.

    8 votes
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    0 comments  ·  Control  ·  Admin →
  18. 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…

    6 votes
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  19. mechanical efficiency of pumps

    Currently mechanical efficiency of pumps is assumed to be 0.78 for purpose of sizing and does not allow user input. We recommend to make this as an user input with default.

    3 votes
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  20. 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…

    15 votes
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    1 comment  ·  Other  ·  Admin →
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