Client-side building simulation

EnergyPlus in the browser

The US Department of Energy whole-building engine, compiled to WebAssembly and running inside this tab. It solves a single free-running zone against Denver design conditions, or against any of 17,292 weather stations and the design conditions that come with them. The model, the solver and the results never leave your machine — there is no server behind this page.

EngineEnergyPlus 26.1.0
RuntimeWebAssembly
UploadNone

Fig. 1 Zone mean air temperature against outdoor drybulb. The model geometry at left is drawn from the surface vertices in the IDF and tinted by the zone's mean result.

Results schedule

Project—1ZoneUncontrolled · free-running · south glazing and overhang added
LocationDenver Centennial, CO—
Run typeDesign dayTwo ASHRAE sizing conditions
Timestep—Reported hourly
Output variables—Recorded to the ESO
Severe / warnings—From eplusout.err
Exit code—0 is a clean run
SheetE-01 · Rev A—
Engine console 

      


      

        Disclosure
        

          

            

              This demo is an independent project. It is not affiliated with, endorsed by,
              or sponsored by the National Renewable Energy Laboratory, the U.S. Department of
              Energy, or any other EnergyPlus copyright holder. The name "EnergyPlus" is used here
              solely to identify the software this page runs — EnergyPlus version 26.1.0 software,
              compiled to WebAssembly and redistributed through the
              @idfkit/engine-assets npm package.
            

            

              The page loads @idfkit/engine, which is MIT licensed; the WebAssembly
              binaries, the input dictionary and the reference datasets it runs are derived from
              EnergyPlus and are licensed separately. Both licenses are reproduced below, as
              distributed on npm.
            

          


          

              
@idfkit/engine · MIT

              
MIT License

Copyright (c) 2026 idfkit contributors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

---

NOTE: The MIT License above covers only the loader, worker, ExpandObjects
bindings and output parsers authored in this repository. The WebAssembly
binaries and data files under assets/ are derived from EnergyPlus and are
licensed separately; see LICENSE.txt and NOTICE.

          


          

              
EnergyPlus version 26.1.0 software · bundled by @idfkit/engine-assets

              
EnergyPlus, Copyright (c) 1996-present, The Board of Trustees of the University of Illinois, The Regents of the University of California, through Lawrence Berkeley National Laboratory (subject to receipt of any required approvals from the U.S. Dept. of Energy), Oak Ridge National Laboratory, managed by UT-Battelle, Alliance for Energy Innovation, LLC, and other contributors. All rights reserved.

NOTICE: This Software was developed under funding from the U.S. Department of Energy and the U.S. Government consequently retains certain rights. As such, the U.S. Government has been granted for itself and others acting on its behalf a paid-up, nonexclusive, irrevocable, worldwide license in the Software to reproduce, distribute copies to the public, prepare derivative works, and perform publicly and display publicly, and to permit others to do so.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

(1) Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

(2) Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

(3) Neither the name of the University of California, Lawrence Berkeley National Laboratory, the University of Illinois, U.S. Dept. of Energy nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

(4) Use of EnergyPlus(TM) Name. If Licensee (i) distributes the software in stand-alone form without changes from the version obtained under this License, or (ii) Licensee makes a reference solely to the software portion of its product, Licensee must refer to the software as "EnergyPlus version X" software, where "X" is the version number Licensee obtained under this License and may not use a different name for the software. Except as specifically required in this Section (4), Licensee shall not use in a company name, a product name, in advertising, publicity, or other promotional activities any name, trade name, trademark, logo, or other designation of "EnergyPlus", "E+", "e+" or confusingly similar designation, without the U.S. Department of Energy's prior written consent.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.