In org mode, I have a set of tasks with time estimates. I'd like to sum the time estimates only for those tasks not marked DONE, to get an estimate of the remaining time to completion.

To give a toy example, suppose my tasks are:

* A sample project
** DONE Task 1
   CLOSED: [2022-03-25 Fri 21:30]
   :PROPERTIES:
   :EFFORT:   2:00
   :END:
   :LOGBOOK:
   CLOCK: [2022-03-25 Fri 20:30]--[2022-03-25 Fri 21:30] =>  1:00
   :END:
** TODO Task 2
   :PROPERTIES:
   :EFFORT:   1:00
   :END:
** TODO Task 3
   :PROPERTIES:
   :EFFORT:   0:30
   :END:

My column set up is:

#+COLUMNS: %38ITEM(Details) %TAGS(Context) %7TODO(To Do) %6CLOCKSUM(Clock) %5Effort(Est){:} 

When I bring up column view, I get an estimate of 3:30, the sum of all the tasks. But what I'd like is an estimate with only the tasks not marked DONE -- 1:30. Is there a way to achieve that?