EnergyPlus

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  1. Take advantage of AVX

    AVX increases the vectorization pipeline but the way EnergyPlus code is currently structured makes it difficult for the compiler to automatically and fully use newer instructions and bigger SIMD pipelines. This may change if optimized linear algebra libraries are used in EnergyPlus and code is refactored.

    4 votes
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    1 comment  ·  Performance  ·  Admin →
  2. 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.

  3. keep solar datasets up to date

    The solar datasets SandiaPVdata.idf and SolarCollectors.idf have not been updated in quite a while, but could be annually like the LCCusePriceEscalationDataSetYYYY.idf is. NREL's System Advisor Model (SAM) comes with several CSV libraries that could be used for this.

    https://sam.nrel.gov/libraries

    1 vote
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  4. 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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  5. Mexico

    Good evening,

    In the weather data Region 4, you have Mexico in Central America which is incorrect because is part of North America. I just wanted to point this mistake.

    Best regards.

    1 vote
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    0 comments  ·  Weather  ·  Admin →
  6. Account for DOAS air when sizing zone units

    I cannot believe this is not a feature request but I could not find it so here goes.

    If you have a DOAS system in E+ (eg Fan Coils of any kind, radiators, etc) combined with a ventilation system, E+ does not currently take into account heating and/or cooling effects of the DOAS air when sizing the zone units (coils and fans)

    This is a gross error. It is very common in DOAS systems for the air to be conditioned for dehumidification, meaning that air could be supplied from the DOAS system as low as say 13C / 55F and…

    2 votes
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  7. include the most recent life-cycle cost data from NIST

    The LCCusePriceEscalationDataSetYEAR IDFs included with EnergyPlus seem to lag behind the published report from NIST by a year. For example, version 8.8.0 (Sep 2017) includes 2016 data rather than 2017 data. The NIST report is published each spring so could be incorporated into the fall release.

    1 vote
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    0 comments  ·  Economics  ·  Admin →
  8. Data center modeling

    HVAC equipment (chillers, towers, water coils and DX coils) to cool data centers are operating at higher temperatures (e.g., supply air temperature and supply water temperature). EnergyPlus equipment models and performance curves are mostly designed/based on human comfort applications which usually have lower supply temperatures. There is a need to verify the accuracy of extending the existing HVAC equipment models and curves from human comfort applications to data center applications. This is a request from ASHRAE TC 9.9 and Standard 90.4.

    3 votes
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    3 comments  ·  Other  ·  Admin →
  9. 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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  10. Allow Use of CSS with HTML Tabular File

    The current HTML tabular file is used by almost all EnergyPlus users but is clunky looking and could be made much more attractive and easier to read if a CSS style sheet could be referenced. A CSS style sheet could also be used to make table of contents easier to access so that users could get to it more quickly. In order to make this happen the HTML generated by EnergyPlus needs to be cleaned up and made more compatible with a style sheet. For example, multiple levels of headings should be used, table header rows should be specifically identified,…

    4 votes
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    0 comments  ·  Output  ·  Admin →
  11. Add Radiant Terminal Units to HVAC Templates

    Add a HVAC template for radiant zone terminal units. Currently (v8.7), if you want to implement radiant with DOAS, then you have to use a roundabout way of implementing it by first using the baseboard heat template and then replacing the objects. It would be nice to have the radiant terminal units as an option in the templates.

    4 votes
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    0 comments  ·  Input  ·  Admin →
  12. ASTM C1340 convection algorithm for attic spaces

    The calculation of convection coefficients on the surfaces for spaces representing attics in EnergyPlus has been shown to have inaccuracies when compared to empirical data and building models that specialize in attics. The ASTM C1340 standard has a set of correlations for these convection coefficients that has been empirically validated. An EMS approach to implementing these convection coefficients is available, but it would be much more usable to have it incorporated as a new object in EnergyPlus.

    3 votes
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    0 comments  ·  Envelope  ·  Admin →
  13. Airflow Network Duct Autosizing

    Autosize the ducts in AirflowNetwork based on Manual D. Automatically sizing ducts for desired flow rates will simplify specification of more complex models. NREL residential has a Manual J OpenStudio measure, so this could be done in OpenStudio, but the current feeling is that it’d be better in EnergyPlus

    2 votes
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    1 comment  ·  Air Flow  ·  Admin →
  14. Allow multiple air loops in the Airflow Network model

    The existing AirflowNetwork model only allows one air primary loop to calculate the energy losses for an air distribution system. This restriction makes the model only able to simulate energy performance with air distribution system losses in residential homes and small commercial buildings. Large commercial buildings are not covered by the model, because multiple air distribution systems, equivalent to multiple air primary loops in EnergyPlus, are expected. In order to make the AirflowNetwork model applicable to large building simulations, multiple air primary loops must be allowed.

    3 votes
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    0 comments  ·  Air Flow  ·  Admin →
  15. Improve fan support in Airflow Network

    Improve fan support in AirflowNetwork, including support for the new system fan model, support zone-induced air flow by a constant volume fan (described in Zone_2007_06.doc), and support for dedicated supply fans.

    2 votes
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    1 comment  ·  Air Flow  ·  Admin →
  16. Validate E+ according to European standards

    I have found 1 report of E+ being validated according to the European NEN-EN-ISO 13791 standard, but that was over E+ version 8.2. As a European user I need to be able to show that E+ is validated against the standard mentioned above, as well as standards NEN-EN-ISO 15255 and NEN-EN-ISO 15256. The ASHRAE validation does not have the same level of authority on this side of the pond, since it has assumptions that are common for the US and Canadian market. EU countries simply approach energy use and indoor climate in a different way.

    Some people who are unfamiliar…

    3 votes
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  17. New Cross Platform and Modern EP-Launch

    EP-Launch Lite that is distributed on non-Windows installs of EnergyPlus is not functionally equivalent to EP-Launch on Windows. It does not support all the same utilities or options. EP-Launch has not had a significant GUI update in many years. EP-Launch would be rewritten to have a more modern GUI while supporting all the same utilities and options and would be made to be cross platform compatible.

    1 vote
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  18. Alternate simulation initialization (warmup) options

    EnergyPlus “runs” the first day of the environment (starting with a set of hardcoded initial conditions: temperatures are initialized to 23C and zone humidity ratios are initialized to the outdoor humidity ratio) until the loads/temperature convergence tolerance values are satisfied (next two fields) or until it reaches “maximum number of warmup days”

    Other programs offer different initialization methods, such as a user-specified number of days to simulate prior to the simulation start date. Recent comparisons related to ASHRAE Std 140 development have shown that the impact on results in the first simulation month can be significant.

    1 vote
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    1 comment  ·  Other  ·  Admin →
  19. New single-duct constant volume air terminal without reheat

    The existing AirTerminal:SingleDuct:Uncontrolled is different from all other terminal units. It only has a single node (not an inlet and outlet) and it sits directly on the zone equipment list instead or being referenced by a ZoneHVAC:AirDistributionUnit object. This causes fits for interfaces, and it prevents this terminal unit from using the simple duct-leakage features in ZoneHVAC:AirDistributionUnit.

    Propose adding a new terminal unit type AirTerminal:SingleDuct:ConstantVolume:NoReheat that has an inlet and outlet node and sits under an air distribution unit. Then deprecate the old AirTerminal:SingleDuct:Uncontrolled object.

    Reference issue #4988
    https://github.com/NREL/EnergyPlus/issues/4988

    2 votes
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  20. Add/update Performance Data for key systems such as chillers, boilers, CHP, etc.

    The E+ performance curve datasets have not been updated for a long time and the available performance data seems to have mostly gotten in there due to the manufacturer's interest (guess) to provide that data set. In short, these performance data sets are in most cases generic and make the use of E+ for complicated systems such as combined heat and power, accurate part-load performance of chillers/boilers, multi speed coils, etc. inconsistent if not unreliable depending on the modeler's expertise.

    Many modelers have sheets or other simple tools to transform some datasheets to performance curves - it might be worth…

    2 votes
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    0 comments  ·  Performance  ·  Admin →
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