EnergyPlus Transition FAQs

We are transitioning to EnergyPlus as the sole energy analysis engine for our Real-Time Analysis, and eventually for the entire Sefaira product suite.

This is the first step in a larger transition to a collaborative platform in which multiple members of a project team (architects, specialists, and engineers) can work together on the same Sefaira project. A consistent analysis engine is a prerequisite for this change, and the EnergyPlus engine provides the advanced analysis capabilities that some team members require.

For now, you can opt to use either the old analysis engine (Fulcrum) or EnergyPlus -- this option is in the Settings menu. Within the next few months we’ll decommission the old engine and EnergyPlus will become standard.

Sefaira Architecture users take note: for more information about uploading to the WebApp during this transition phase, go here.

How will the plugin change?
For Real-Time Analysis users, this is mostly a “behind the scenes” change -- meaning the plugin interface and functionality won’t change much.

  1. HVAC Systems: The biggest user-facing change is a new approach to HVAC systems, in which an appropriate HVAC system is automatically selected based upon the selected Building Type and Location. For example, Healthcare and Laboratory projects will use systems designed for high ventilation requirements. European projects will all have heat recovery and full fresh air ventilation. And as a result, absolute energy results will be closer to measured energy usage for typical comparable buildings. (You can learn more about how systems are selected here.)
  2. Properties: There will also be minor changes to the Properties tab, in order to align the inputs with EnergyPlus requirements.

What’s the difference between Fulcrum and EnergyPlus?
Fulcrum is based upon ASHRAE’s Radiant Time Series method, which is primarily designed as a load calculation methodology. Because Sefaira’s original applications were for architects, who are focused on passive measures designed to reduce building loads, this was a sensible approach. Now that Sefaira is focusing on other team members, who need functionality that includes robust HVAC analysis, we are moving to a full-featured simulation engine.

EnergyPlus has been developed over many years with funding from the U.S. Department of Energy, has been rigorously tested by thousands of academics and practitioners all over the world, and is the same engine used by many more detailed, specialist analysis tools. You can learn more about EnergyPlus on its website.

Will my results change?
Likely, yes. The new results will reflect a simulation based upon a typical HVAC system, which will yield results that are generally closer to measured energy usage for a typical comparable building. EnergyPlus also uses a different calculation methodology than the previous engine (Fulcrum).

The degree of variance in results will vary from project to project. However, it’s worth noting that while the absolute value of the results will change, the relative improvement of different design options will likely remain consistent. The Fulcrum engine had undergone validation in accordance with ASHRAE Standard 140, and demonstrated good agreement with other analysis engines across a range of outputs -- so in general terms the old results will have good agreement with the new results.

If you’re in the middle of a project, you will continue to have access to the old analysis engine (Fulcrum) during the transition. 

If you have specific questions about a project, our Customer Success team will be happy to assist you: email us at

How can I learn more?
We will be sharing our vision and product plans in a series of customer webinars, which include live Q&A. We will host sessions at 3 different times to allow as many of our customers as possible to participate. You’re welcome join any of the sessions, regardless of where you are.

Keep an eye on your inbox for more details and the webinar invitations. 

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    Francis Cooke

    Good work guys, Looking forward to the transition!
    If only we had a timeline for getting off fossil fuels . . .