Client-side building simulation

EnergyPlus in the browser

EnergyPlus, compiled to WebAssembly and running inside this tab. The model, the solver and the results never leave your machine.

About this page

The U.S. Department of Energy whole-building engine. It solves a single free-running zone against any of 17,292 weather stations and the design conditions that come with them. The sheet opens on Denver's design days, so there is a result on the page before you have chosen anything. There is no simulation server behind this page.

EngineEnergyPlus 26.1.0
RuntimeWebAssembly
Toolkitidfkit
Simulation serverNone
Units

Every number reads in the system you pick. The model stays in SI.

Fig. 1 Zone mean air temperature against outdoor drybulb. Geometry at left is drawn from the IDF's surface vertices, tinted by the zone's mean result.

Results schedule

The targets

What each standard asks of the finished building, against what the last run read.

Where the specifications are

The specifications that would get you there are on the console, folded beside the controls they set; this board only keeps the score.

Chase a standard to hold its worst line up beside the drawing; press again to put it down.

More on chasing

Chased, a standard collapses to its single worst line, held up beside the drawing while you work, with a ghost of where that margin stood when you took hold — so you can see whether the control under your hand is helping without reading a dozen rows a screen away. Chasing measures; it decides nothing.

Kept schemes

A kept scheme is the whole desk, stored in this browser as the link Copy scheme link hands out.

About kept schemes

One format for keeping and for sharing, carried forward by the same version ledger, so a scheme kept today still opens on a page that has since grown a channel. It is held in this browser and goes nowhere else. An option can be put down, another one worked, and the two set side by side.

Nothing kept yet. Save this scheme, in the run log at the left, keeps the desk and what it was reading.

Project—1ZoneUncontrolled · free-running baseline · 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—
Drawn by

Your name goes at the top of every IDF this desk writes. Kept in this browser, never in a shared link.

About signing

Above the toolkit that wrote it and the build of this sheet. A scheme you send carries the building, not whoever drew it.

Engine console 

      


      

        Revisions
        

          

            Generated from CHANGELOG.md in the repository.
          

        

      


      

        Disclosure
        

          
          

            
Colophon

            

              Built by Samuel Letellier-Duchesne, who works on building energy simulation at
              Introba
              and maintains idfkit:
              an open-source toolkit for reading, writing and running EnergyPlus models, meant to
              be one set of common developers tools for javascript and python. Shoebox is that toolkit in a browser — @idfkit/core
              builds and writes the model every figure on this sheet is read back off,
              @idfkit/weather finds the stations the picker offers, and
              @idfkit/engine runs them using the EnergyPlus engine.
            

          


          

            

              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.