EnergyPlus (commonly called Eplus, Energy+, or E+) is a building simulation engine that takes input data (in the form of text) and runs a building simulation and creates detailed results focused on building energy consumption, but also much more.
Why is Eplus important?
EnergyPlus is an extremely powerful energy modeling engine. It is funded by the U.S. DOE and is the brainchild of many PhDs using extremely powerful algorithms. It is also built to allow "add-ons", so 3rd parties can work with it to develop additional features.
What is a GUI?
If you get started with EnergyPlus, you'll hear this word "GUI" - which means "Graphical User Interface", which doesn't really explain much. Basically, since EnergyPlus is an engine that uses text as an input, it is a bit overwhelming to start using on its own because it's like using DOS (all text)
So, 3rd parties created programs that make it look better. (Instead of seeing a bunch of text, you can actually see the building). So, the GUI makes it easier to do many things, especially creating the building. However, a GUI is not necessary to run EnergyPlus, but makes it much easier to get started.
Energy-Models.com is a site for energy modelers, building simulators, architects, and engineers who want learn the basics, to advanced concepts of energy modeling. We've got online training courses and tutorials for eQUEST, Trane TRACE 700, OpenStudio, and LEED for energy modeling. All our energy modeling courses are video based. What better way to learn energy modeling software than screen-casts of exactly how things are done?