How different simulation modes work

There are 2 different run modes in Sefaira's web-app. This article explains how to switch between them and how runs are kicked off in each mode.

Simulation modes and controlling settings

The two different run modes in Sefaira are:

  • Start a simulation "Whenever I make a change". We also refer to this as Automatic Run Mode.
  • Start a simulation "When I click the run button". We also refer to this as Run on Demand Mode.

You can choose which run mode you are using when in a project by clicking settings. Changing the settings will affect all your projects and will be remembered until you decide to change it again.

Automatic runs were the original mode and default mode for Sefaira until 23 Jan 2017.

We added Run on Demand mode on September 16, 2016 and made it the default mode on 23 January, 2017.

How Automatic Run Mode works

Automatic run mode works as follows:

  • If you make any change to an input Sefaira waits 2 seconds then starts a new simulation. All input changes made in the 2s window will be included in the new run.
  • If you make any changes while a simulation is in progress, Sefaira opens a new 2s window and then restarts the run after the 2s is up. 
  • You can keep making changes as often as you like, once you have finished making changes, the last simulation triggered will include the final set of inputs you have entered.
  • You cannot use Automatic Run Mode when running Comfort Calculations.

We believe automatic run mode makes using Sefaira faster than having a run on demand mode, but we also received a lot of feedback that customers wanted a run button.

How Run on Demand mode works

Run on Demand mode works as follows:

  • If you make any change to an input Sefaira will add a green Update button to the left of your iteration as shown below. 

  • You can make as many changes as you want while the green Update button is showing.
  • After you click Update, a run will commence with the inputs that were set at the point of clicking Update. The button will change to show you the simulation is in progress.

  • If you change an input while a simulation is in progress the simulation will be aborted and the Update button will re-appear. There is no way to retrieve the old simulation except to run it again.
  • You must be in Run on Demand mode to do Comfort analysis.


We added Run on Demand to support customers who found Automatic Run mode confusing or stressful. We also enforce it for simulations with a higher computational load, like Thermal Comfort calculations.

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