The Building Energy Modeling (BEM) sub-program is an important part of BTO and its Emerging Technologies Program. BEM is a versatile, multipurpose tool that is used in new building and retrofit design, code compliance, green certification, qualification for tax credits and utility incentives, and even real-time building control. BEM is also used in large-scale analyses to develop building energy-efficiency codes and inform policy decisions. So what exactly is BEM? And what roles does the U.S. Department of Energy (DOE) play in the BEM industry and community? Learn more about BEM, its uses, and BTO’s BEM portfolio ►

Software and Project Portfolio

EnergyPlus is DOE's open-source state-of-the-art whole building energy simulation engine.
Learn more
OpenStudio is an open-source software development kit (SDK) for energy modeling with EnergyPlus.
Learn more
Spawn-of-EnergyPlus (Spawn)
Spawn is a next-generation BEM-controls engine based on open-standards for co-simulation (FMI) and equation-based modeling (Modelica).
Learn more
Building Energy Modeling Project Portfolio
BTO's active and completed Building Energy Modeling projects.
Learn more

End-Use Breakdown: The BEM Blog

Collaboration + Automation = Pollination
Long known for daylighting, energy, and comfort analysis plugins for Grasshopper/Rhino3D, Ladybug Tools introduces a new tool-agnostic simulation ecosystem that acts as a collaborative workspace for experts, beginners, and application providers.
Learn more
Cove.Tool Officiates Perfect Marriage Between Reduced Order Modeling and OpenStudio
Cove.tool is using OpenStudio to integrate detailed energy simulation into its reduced-order modeling design platform, giving architects an end-to-end workflow with capabilities tailored to the needs of different design stages.
Learn more
It's Alive! After Five Years in the Lab, Spawn (of EnergyPlus) is Finally Here
For the past five years, DOE and the national labs have been developing a next-generation simulation engine that bridges the worlds of BEM and controls. In May of this year, Spawn, was released as part of the Modelica Buildings Library.
Learn more
EnergyPlus Turns 20!
On April 12, 2021 EnergyPlus, DOE's flagship BEM engine celebrated its twentieth birthday. Several of those who were there at the beginning look back at those early days and remark on the changes they've seen in the last two decades.
Learn more

Resources for Modelers and Stakeholders

Unmet Hours
A peer-to-peer help and support forum for BEM with search, voting, and notification tools. BTO uses UnmetHours to support EnergyPlus and OpenStudio.
Learn more
Building Energy Software Tools Directory
Hosted by IBPSA-USA, this directory has vendor-driven content and supports images, video, ratings, reviews, and search, sort, and filter functions.
Learn more
BEM Guide for Owners and Managers
Created by Rocky Mountain Institute, this guide gives BEM clients like building owners information needed to engage with and contract BEM services.
Learn more