There are two general reasons why two of the same simulations do not match exactly.
1. LightStanza uses Radiance as its engine, which, like other ray-tracing programs, uses monte-carlo ray-tracing and hence there will always be some randomness in the results. To mitigate this problem, run calculations at higher quality settings where variances will be insignificant.
2. LightStanza frequently releases new versions to give users the most accurate simulations, latest versions of Radiance, new features, latest code compliance scoring updates, optimal workflow, bug fixes among other improvements. As a result a simulation run a year ago may have a different result than a simulation run today. To mitigate this issue, Version numbers are recorded with each simulation in their “Advanced Details”. In addition a record of these changes are listed in the “Version History” on the top-right menu of LightStanza.
As a result, we recommend to only comparing data from the same version of LightStanza. If old project data needs to be reviewed and expanded upon, we recommend re-running it to get it up to date. For the most robust way of ensuring you have the correct results will be to re-upload your model to LightStanza.