jEPlus — The Complete Guide: Free Parametric Studies for EnergyPlus — Hundreds of Variants in One Run
jEPlus is an open-source (GPLv3) tool that wraps EnergyPlus (and TRNSYS) for parametric studies. You define parameters — insulation thickness, glazing type, building orientation or HVAC set-points — and jEPlus generates every combination, runs them in parallel and collects the results into one table for comparison.
jEPlus
jEPlus (open-source project)
Parametric-study shell for EnergyPlus and TRNSYS — run hundreds of design variants and compare them.
Get it from the vendorWhat you get
- Tagged template — mark the changing values in the input file, and the tool substitutes them in each run.
- Full factorial or sampling — every combination, or a random sample when the space is too large.
- Parallel runs — using all the computer’s cores.
- Result collection — extracting key values from each run into one file.
- GUI and command line — work in a window or integrate into scripts.
Who it suits
Energy consultants and researchers who want to know which design decisions really change consumption, and to run sensitivity checks and optimisation. It is written in Java and requires a separate EnergyPlus installation, in the version that matches the input file. Start with a base model that runs cleanly, and only then add tags.
Related tools
To build the base model in a graphical interface — OpenStudio. To analyse results and plot them — Python or R. To check the thermal comfort of the variants — CBE Thermal Comfort Tool.
EnergyPlus
US Department of Energy
Annual building energy simulation — envelope, HVAC, thermal comfort and daylight. The US DOE engine.
Get it from the vendorOpenStudio
National Renewable Energy Laboratory
Graphical workflow on top of EnergyPlus — geometry, systems and scenario comparison.
Get it from the vendor
Python
Python Software Foundation
The language behind most modern engineering computation, and its full ecosystem.
Get it from the vendor
CBE Thermal Comfort Tool
Center for the Built Environment, UC Berkeley
Thermal comfort calculation to ASHRAE 55 and EN 16798, in the browser.
Get it from the vendorThe bottom line
jEPlus turns a “what if” question into hundreds of organised answers — completely free, including for commercial work.