How aggregations are performed are determined entirely by your own continuous view definitions [0]. In this case I'm guessing you'd want to include a time-based column in the aggregation GROUP BY clause.

And since PipelineDB is a PostgreSQL extension, you can use the timestamptz type (which includes timezone support), and in general you could pretty easily simply normalize your event timezones in your continuous view definitions. When you're reading aggregate data back out, you could cast the time-based column using whatever timezone the client prefers.

Thanks for the question--I hope that was helpful!

[0] http://docs.pipelinedb.com/continuous-views.html