Julien Marrec
Owner at EffiBEM
Lorient, Brittany, France
Summary
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Rockstar🎓
Top SchoolJulien Marrec is an energy engineer and founder of EffiBEM with 11 years of experience simplifying Building Energy Modeling (BEM) workflows and promoting greener buildings. Based in Lorient, Brittany, he blends deep domain expertise in energy audits and simulation with hands-on software development to automate repetitive BEM tasks and accelerate decision-making on energy efficiency measures. Julien is an active open-source contributor to prominent projects like EnergyPlus and OpenStudio, and has improved build automation and CI/CD for libraries such as CoolProp and SWIG, demonstrating strong backend and DevOps skills. His background from Mines Saint-Étienne and early field experience inform a pragmatic approach to building tools that work with limited inputs for specific use cases. Notably, he moves between HVAC/daylighting simulation internals and Python/C++ tooling, making him equally comfortable in scientific codebases and production build pipelines. He aims to put practical, software-driven energy modeling capabilities directly into practitioners’ hands.
11 years of coding experience
6 years of employment as a software developer
Ingénieur Civil des Mines, Double-major Master in Engineering and Management, Ingénieur Civil des Mines, Double-major Master in Engineering and Management at Ecole nationale supérieure des Mines de Saint-EtienneClasse Préparatoire aux Grandes Ecoles, PC*, Classe Préparatoire aux Grandes Ecoles, PC* at Lycée de Kérichen, Brest
French, English, Spanish
Stackoverflow
11,845reputation
1.3mreached
211answers
14questions
pandas
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dataframe
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excel
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python
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Github Skills (61)
unit-testing10
github-ci10
c-language10
python10
package-management10
conan10
testing10
windows10
pandas10
packaging10
build-system10
cmake10
python-packaging10
autotools10
cicd10
Programming languages (20)
Github contributions (5)
NREL/OpenStudio
Oct 2015 - Jan 2023
OpenStudio is a cross-platform collection of software tools to support whole building energy modeling using EnergyPlus and advanced daylight analysis using Radiance.
Role in this project:
Back-end Developer & DevOps Engineer
Back-end Developer & DevOps EngineerContributions:1297 reviews, 4792 commits, 872 PRs in 7 years 4 months
Contributions summary:Julien primarily focused on improving the build process and addressing compiler-related errors, such as those encountered in GCC 7, suggesting a focus on backend development and build infrastructure. Their contributions included fixes to unit tests and the removal of a double implicit conversion, indicating a focus on code quality and preventing compilation warnings. The user also implemented modifications related to the Python bindings, showing a strong understanding of the project's build system.
renewable-energyhpc-applicationssoftware-toolsenergy-modelingcross-platform
NREL/EnergyPlus
Feb 2016 - Jan 2023
EnergyPlus™ is a whole building energy simulation program that engineers, architects, and researchers use to model both energy consumption and water use in buildings.
Role in this project:Back-end Developer
Back-end DeveloperContributions:11 releases, 550 reviews, 1401 commits in 7 years
Contributions summary:Julien's contributions are focused on the modification and integration of components within the EnergyPlus codebase. They worked on integrating changes from the upstream development branch, specifically focusing on updates to dependency bumps and incorporating new features or fixes related to HVAC and daylighting functionalities. The user implemented changes across multiple source files including the tst directory for unit tests and source directory to make the code compatible with new features.
renewable-energypower-systemsenergy-consumptionenergy-simulationsimulation
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