Is there a link to download the plugin of Sefaira for SketchUp 2016?
Sefaira is now part of SketchUp Studio (2019), if you start a trial, you can download it through your Account Management Portal.
There is a bulk installer for version 2017 and 2018, but I do not know if the 2016 version is still available or will work in version 2016 @niraj.poudel ?
FWIW: Sefaira was always subscription based and a cloud service, the plugin is only to communicate the design envelope with the servers. To use it, you would need a subscription for Studio.(So why not use 2019)
Revit users who want energy balance calculations and daylight visiulisation can also download the plugin if they start a SketchUp Studio trial or, as existing customer, have a subscription to Studio allready. (And why not use SketchUp 2019 to build the design envelope?)
We officially support the 3 most recent releases of the SketchUp client which is currently 2017, 2018 and 2019. This simply means that we proactively fix bugs associated with those versions (it doesn’t mean we’re switching off support for older versions).
As a result, although we have not tested since releasing, I would be very surprised if the installer in the account management portal did not work with SketchUp 2016.