AixWeather

A weather data generation tool for building energy system simulations. Pull, Transform, Export.

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 AixWeather 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 AixWeather we follow this local tradition.

If you have any questions regarding AixWeather, feel free to contact us at aixweather@eonerc.rwth-aachen.de.

WebApp

For fast access without setup, use the WebApp. The repository AixWeather-WebApp contains the corresponding WebApp for this repo. This repository contains the functionalities useful for, e.g., automation of tasks.

How to use

For each data origin, a class is defined. Use generic functions to create the desired output file. See the examples to know how to use them.

Tool structure and overview

This tool consists of three layers:

1. Import raw weather data from several sources

2. Transform the weather data to a defined core format with consideration of:

   2.1. Time zone

   2.2. Time of measurement (whether a value at a certain time stamp is for the indicated time or, e.g., the average of the preceding hour)

   2.3. Avoidance of smoothing through interpolation (pass through variables without interpolation if possible)

   2.4. Units

   2.5. Calculate missing variables from available ones, e.g., horizontal direct radiation from diffuse and global radiation

   2.6. Missing data.

3. Transform the core-format data to your desired output format

Overview

Known limitations:

• only hourly data

Chances:

• generic code base that allows for fast and easy extensions to both other import formats and output formats

DWD station IDs and DWD MOSMIX station IDs

The station IDs for the DWD weather stations to pull historical data from are listed here. Only german stations available. Aachen would be 15000.

The DWD MOSMIX station IDs for the DWD forecast are listed here or located on a map here. Worldwide station available. Aachen would be 10505.

You may use the imported package Wetterdienst to search for stations automatically, as described here.

Sources of information for corresponding data formats

Input

Test Reference Years (TRY):

Handbuch.

TRY data can be downloaded from the DWD (sign up required but for free) TRY data sets.

Additional information on the suitability of TRY data (last update: 2019): There are typical TRY datasets grouped by the year of publication:

• 2004 datasets: (DWD; some errors in solar radiation; dataset should be avoided).
• 2010 datasets: suitable for EnEV and GEG, not for solar thermal simulations.
• 2015 datasets: not suitable for EnEV and GEG, but for solar thermal simulations
• Overall: Reliable quantities in TRYs are only the air temperature and the global radiation!

DWD historical: open data website

DWD forecasts (MOSMIX i.e. KML files): open data website go to content.log.bz2.

EnergyPlus (EPW):

For format information, see the corresponding output format description.

Online sources for EPW data: https://climate.onebuilding.org/default.html and https://www.ladybug.tools/epwmap/

ERC data:

This data is from the weather station of the Institute for Energy Efficient Buildings and Indoor Climate (RWTH). Access requires user credentials. Such credentials are pre-defined if you use the WebApp.

Output formats

EnergyPlus (EPW):

3rd party format description

Modelica ReaderTMY3:

TMY3 reader from the IBPSA library used in the AixLib library. Model info at OpenModelica. It claims to use mainly TMY3 data, though we found that the pressure is used in mbar instead of Pa. Further deviations possible.

Additional information for AixLib users.

Weather data usage in the low order model (LOM):

Used in LOM:

• TDryBul
• RelHum
• TBlaSky (calculated via HInfHor, TDryBul, TDewPoi, and OpaSkyCov)
• HGloHor
• HDifHor
• HDirNor

Not used in the LOM:

• total sky cover
• ceiling height
• wind direction
• wind speed
• atmospheric pressure

Unconverted to x

exports the core data without conversion to .csv, .json, or .pickle files.

How to contribute to the development

You are invited to contribute to the development of this weather tool. Issues can be reported using this site's Issues section. Furthermore, you are welcome to contribute via Pull Requests. More info on how to contribute can be found here.

License

The weather tool 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 license.