rwth-ebc/aixlib

A Modelica model library for building performance simulations

AixLib

AixLib is a Modelica model library for building performance simulations.
The library contains models of HVAC systems as well as high and reduced order building models.
It is being developed at RWTH Aachen University, E.ON Energy Research Center, Institute for Energy Efficient Buildings and Indoor Climate (EBC) in Aachen, Germany.

As the library is developed at RWTH Aachen University's EBC, the library's name AixLib is derived from the city's French name Aix-la-Chapelle, which the people of Aachen are very fond of and use a lot. With the name AixLib we follow this local tradition.

If you have any questions regarding AixLib, feel free to contact us at [email protected].

Clone repository

• To clone the repository for the first time run:
  git clone --recurse-submodules https://github.com/RWTH-EBC/AixLib.git
• If you have already cloned the repository, run:
  git submodule update --init --recursive
• The default branch of AixLib is the development branch. This means that after cloning the repository, you always checked out the development branch.

Release versions

The latest version is always available on the release page and defined in AixLib's package.mo.

How to cite AixLib

We continuously improve AixLib and try to keep the community up-to-date with citable papers. Please use the following article for citations when using or enhancing AixLib.

@article{doi:10.1080/19401493.2023.2250521,
author = {Laura Maier and David Jansen and Fabian Wüllhorst and Martin Kremer and Alexander Kümpel and Tobias Blacha and Dirk Müller},
title = {AixLib: an open-source Modelica library for compound building energy systems from component to district level with automated quality management},
journal = {Journal of Building Performance Simulation},
volume = {0},
number = {0},
pages = {1-24},
year = {2023},
publisher = {Taylor & Francis},
doi = {10.1080/19401493.2023.2250521},
URL = {https://doi.org/10.1080/19401493.2023.2250521 },
eprint = {https://doi.org/10.1080/19401493.2023.2250521 }
}

Publications using AixLib

Please see the publications list

How to contribute to the development of AixLib

You are invited to contribute to the development of AixLib. Issues can be reported using this site's Issues section. Furthermore, you are welcome to contribute via Pull Requests. The workflow for changes is described in our Wiki.

License

The AixLib Library is released by RWTH Aachen University, E.ON Energy Research Center, Institute for Energy Efficient Buildings and Indoor Climate and is available under a 3-clause BSD-license. See AixLib Library license.

Acknowledgements

Parts of AixLib have been developed within public funded projects and with financial support by BMWi (German Federal Ministry for Economic Affairs and Energy).

aixlib's Issues

Add acknowledgements

In our acknowledgement section, we should reference our public financial support

Error while simulating examples

Dear AixLib team i am having problems while simulating the library examples. Screenshot of the error is attached.

Typos in radiator

Had a quick look at the radiator model - will fix the typos in the commented code.

Building.LowOrder.BaseClasses.equalAirTemp

working on issue #24 i recognized some potential for enhancement in the current version of the equalAirTemp (e.g. right now only one view factor [phiprivate=0.5 for vertical alignment] is considered)

Should we discuss this in this issue or also in #24

misspell_fixer

@tbeu has applied the misspell_fixer from
https://github.com/vlajos/misspell_fixer
to various Modelica libraries.
This spell fixing script should also be applied to AixLib.
Will send a Pull Request later

Altitude in ASHRAE Validation (high order models)

Altitude has to be set to 1609m in RadOnTiltedSurf_Perez

name clash: HVAC used twice

Your AixLib.package.mo has an annotation which libraries it uses:

annotation(uses(Modelica(version = "3.2.1"), HVAC(version="2.2")));

But HVAC is also used for AixLib.HVAC (and for the directory that contains that sub-package), resulting in an error message when opening AixLib in Dymola. Maybe the library should be renamed LibHVAC or something more meaningful and unique.
Maybe you want, in addition, completely remove the uses HVAC annotation, because most users of AixLib do not have access to that library.

Accessing Output of airload

Dear AixLib,
I am really confused about this. I want to use the simulated airload Temperature ( reducedOrderModel.airload.T ) of "AixLib.Building.LowOrder.Examples.LOEM" and use it to get an estimate of Cooling required using the equation ( Q=m.c.dT) where dT=AT-ST
AT=Airload Temperatue
ST=Set Temperature.

How do i access AT, the simulated airload temperatue?

Illegal inheritance

Warning while loading the file .\AixLib\AixLib\Utilities\HeatTransfer.mo.
The Modelica class of AixLib.Utilities.HeatTransfer.HeatConv_inside (class) and its base class Modelica.Thermal.HeatTransfer.Interfaces.Element1D (model) are not compatible.

HeatConv_inside should be of type model, too.

LOM.SplitterThermPercentAir

I have to objections:

• For what is "AirPercent" in the name?
• The loop connecting input and output can be more efficiently handled by a vectorized equation using .* if necessary
• In the sum equation, the multiplication needs to be done via .*. This might cuase errors if input is a scalar.

Adjusted "Hydraulic Separator" and "Mixing Valve"

Already-developed models for Hydraulic separator and Mixing valve have been adjusted to the new format of AixLib.

Rename variable for differential pressure from p to dp

In AixLib.HVAC.Interfaces.TwoPort, the differential pressure is calculated as variable p, which is described as "Pressure drop between the two ports (= port_a.p - port_b.p)". Renaming to dp would be more coherent with standard conventions and thus less irritating.

Bug in HVAC.HeatGeneration.Boiler

Q_flow_max<< in >>boilerEfficiency<< should be passed from the boiler parameter. At the moment it is set to 20000

Building.LowOrder.Examples not functional

The LowOrderExample does not work and does not include a proper simulation setup. This should be corrected

HeatTransfer.HeatConv uses subscripted modifier (not allowed in Modelica Spec)

The diagram uses

Rectangle[
extent]=...

This is not allowed according to the Modelica Specification and prevents the library from opening with OpenModelica 1.9.1 beta 4.
(see https://trac.openmodelica.org/OpenModelica/ticket/2663)

Revise Buildings.LowOrder.Validation Test Cases 3,4,6,7,11

The Test Cases

• 3
• 4
• 6
• 7
• 11

are still not sufficient. Here, some further work needs to be done justify the deviations or improve the models

Error in OpenModelica: “The file was not encoded in UTF-8"

Reported via eMail:
Upon Opening the library in OpenModelica, the following error message is given: “The file was not encoded in UTF-8"

LowOrder: ThermalZonePhysics

parameter eowo is not specified for use with record

Correct implementation of a door in AixLib.Building.Components.Walls.Wall model.

The model should allow for doors both for outside and inside walls. However the existence of the door component is conditioned also by the wall being an inside wall. Additionally the U-value of the door should be adapted for an inside wall, as just half a wall and hence half a door is considered.

Implement improved Low Order Model

Implement improved LOM as shown in http://www.ibpsa.org/proceedings/bausimPapers/2014/p1192_final.pdf

Parameters for dynamic ventilation not referenced on room level

The parameters are defined on the floor level in AixLib.Building.HighOrder.House.OFD_MiddleInnerLoadWall.BuildingEnvelope but are not referenced further down in the rooms, so they are not active.

Clean up of low order models

• delete unnecessary models
  • EqAirTempSimple
  • ReducedOrderModelStar
• delete name affix EBCMod
• rename the parameters to be uniform
  • EqAirTemp package
  • ReducedOrderModel package
  • SolarRadWeightedSum
  • ThermalZonePhysics
  • ThermalZone
  • ZoneBaseRecord
• make ReducedOrderModel replaceable, implement choice in higher level models and change default reduced order model in ThermalZonePhysics to the one with decoupled RWin
• clean up ZoneBaseRecord
  • No default values
  • clean up white spaces
  • delete old, unused parameter
• implement choice between CorrG and NoCorrG for higher level models

Building.LowOrder.Validation: update documentation, plots, and simulation times

• The validation examples' documentation for the low order building model should clearly state which variables are compared to the ref.
• The examples should plot this comparison.
• The simulation times should be adjusted to not exceed the last reference day

LowOrder Building - Validation

-translation into English and proper naming
-update CombiTimeTable for inner loads in test cases 5,8,9,10,12 (split the persons share into peopleConvective and peopleRadiative)

Revise LowOrder.ThermalZone

Revise the structure or add additional ThermalZone models (e.g. like it is done in LowOrder.BaseClasses.ReducedOrderMolde/EqAirTemp) in order to operate the ThermalZone with all the different modeling options of #24 and #25

Integration of ASHRAE 140 Validation

Models of ASHRAE 140 Validation should be added (LOM and HOM)

Validation according to ASHRAE 140

Wouldn't it be absolutely wonderful if this awesome building models would be validated according to some standard, let's say ASHRAE 140?
PRemmen, are you feeling up to it?

Revise icons Buildings.LowOrder

The icons need to be revised, the colors might be a bit shiny.

HVACComponentsDevelopment

A branch to develop new HVAC components

Icon for AixLib

Add icon for AixLib

Implementing HVAC from another Library

Dear AixLib Team,
I want to implement a HVAC system from another library inside one of the AixLib
LowOrderModels. The Chiller model and all the components have flow ports(fluids) involved. Is there a way in which i can implement this by modifying the LowerOrderModel? Something like below but instead of getting the temperature from the temperature sensor.. include the chiller(through the flow ports) inside the building.
I would really appreciate the help and any ideas regarding this.

High order examples: Division by zero in pipe

When trying to simulate the high order building model's examples RoomGFOw2 and Appartment_VoWo, simulation fails because the static pipe model divides by zero with lambda2 = 0.

This seems to be a problem with the pipe rather than with the high order examples. For a quick solution, I suggest to replace the static pipe in the examples by the pipe model from MSL.

For the future development an important question is whether to revise the models Pipe and StaticPipe or replace them systematically by other pipe models (from Annex 60 or MSL, for example).
What do you guys think @mlauster, @PRemmen? Others' input is also very welcome of course!

Boundaries of example for dynamic pipe

Both boundaries are set to atmospheric pressure, forward side has h = 1e6. I think this might be an error and instead the forward side should have a slightly higher pressure than the return side boundary?

Update several models to newer versions

Several models also used in AixLib have been improved in another projects. The AixLib models should be updated. All further development of these models shall hence on be done only in AixLib.

Implement Unit Tests

The library should have unit tests for all models as a means of quality control. This should use buildingsPy unit testing routines

Revise Buildings.LowOrder.Validation

Due to parameterization, we do not match the reference values within +/-0.1K. This can be improved.

Add style guide to wiki

Add style guide to wiki for contributions

Documentation for Records in AixLib.DataBase.Surfaces.RoughnessForHT

.. has to be adapted to the AixLib paths

Boolean withFloorHeating in room models from AixLib.Building.HighOrder should be set to false

The default value of the boolean parameter is true. It should be false in order to allow for the changes in model only when explicitly needed. For example AixLib.Building.HighOrder.House.OFD_MiddleInnerLoadWall.BuildingAndEnergySystem.OFD_IdealHeaters has by default the parameter set to true, and in this case it is incorrect.

Test fluid models with Annex 60 base classes

Implement a test to compare models as-is with the same models built on Annex 60 base classes using Modelica Fluid

Packages and models should not be saved into single files

If there are any objections please comment, otherwise we should save each model to a single file as most other libraries do.

package.order

Your package.order is currently broken.
Dymola will silently fix this when opening the library,
OpenModelica will complain, and it will tell you what is broken where.

So, opening the library in OpenModelica from time to time (e.g. after running the integration scripts)
is a good test to see whether the package.order is correct.

HTML tidy

BuildingsPy can call HTML tidy and check the HTML documentation.
The following Python script will print a couple of warnings and errors that should be fixed.

import os
import buildingspy.development.validator as v
moLibsDir = "C:\Users\mthorade\Documents\Dymola"
moLib = "AixLib\Aixlib"
moLibPath = os.path.join(moLibsDir, moLib)
print(moLibPath)

val = v.Validator()
errStr = val.validateHTMLInPackage(moLibPath)
print(errStr)

Remember to change the path.
Before running the script you need to pip install -U buildingspy.
You might also need to pip install -U pytidylib and get tidylib.dll from http://www.html-tidy.org/

Move AixLib from svn to github

== false in EqAirTemp and LowOrder Validation gives Parser Error in OpenModelica

E.g. in EqAirTemp.mo line 40:

if sum(wf_wall) + sum(wf_win) + wf_ground <> 0.00001 == false then

This should be changed to:

if not sum(wf_wall) + sum(wf_win) + wf_ground <> 0.00001 then

@PRemmen can you please check whether that gives the same results?

MultiZone model corrupt at "withWindows=false"

Since the MultiZone model is not part of AixLib yet, this issue is not urgent for now. Should be fixed when integrating MultiZone model into AixLib

More examples for residential and non-residential buildings needed

Start a branch for building application examples for residential and non residential buildings

LowOrderModel remarks from Annex 60

We got some remarks mainly regarding LOM from the Annex 60 group and should consider them.
Mainly, the following items should be done:

• Do not use cardinality as it will be removed from Modelica
• Replace Airload in ReducedOrderModel with Mixed Air volume
• use assert instead of .stream to state warnings

VDI 6007 verification

Due to changes in the reducedOrderModel the example test cases are not working

Naming of thermal mass inconsistent

Most Rooms in the Building.HighOrder Library of AixLib offer a simple radio button to select the Thermal Mass Class. Unlike the whole GUI, the labels assigned (S, M, L) are abbreviations for the German "Schwer", "Mittel" and "Leicht". This is a possible source of confusion, as it could be misunderstood as "Small", "Medium" and "Large".

It suggest renaming the abbreviations to:
S --> high
M --> medium
L --> low