> For the complete documentation index, see [llms.txt](https://docs.betterbuilding.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.betterbuilding.io/support-and-training/other-support/testing-and-verification/energyplus-tm-v-9.5.0-+-22.2-+-25.1/engineering-reference.md).

# Engineering Reference

The EnergyPlus Engineering Reference, also known as the E+ Engineering Reference or ER, is a comprehensive technical guide that provides in-depth information on the underlying physics, mathematics, and algorithms used by EnergyPlus.

The Engineering Reference is intended for advanced users, such as building energy analysts, researchers, and software developers who require a detailed understanding of the EnergyPlus simulation engine. The ER includes detailed descriptions of the algorithms used by EnergyPlus to model building systems, such as heating and cooling equipment, ventilation, and lighting.

The ER also provides guidance on advanced modeling techniques, such as thermal storage systems, renewable energy systems, and ground-source heat pumps. In addition, the ER includes information on how to extend EnergyPlus through user-defined models and interfaces with other software tools.

Overall, the EnergyPlus Engineering Reference is a valuable resource for advanced users who need to understand the technical details of EnergyPlus and how to use it to model complex building systems accurately.

{% hint style="info" %}
Access EnergyPlus 22.2 Engineering Reference [here](https://bigladdersoftware.com/epx/docs/22-2/engineering-reference/index.html).
{% endhint %}


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