Union to Unpivot convert for performance

SELECT

    DISTINCT Remissierdetail.Scode AS oowncode

  FROM Remissierdetail Remissierdetail

  WHERE Remissierdetail.firmnumber   = 'KSH-000001'

  AND Remissierdetail.Scode !        = Rpad(' ',10)

  UNION

  SELECT

    DISTINCT Remissierdetail.Scode1 AS oowncode

  FROM Remissierdetail Remissierdetail

  WHERE Remissierdetail.firmnumber   = 'KSH-000001'

  AND Remissierdetail.Scode1 !       = Rpad(' ',10)

  UNION

  SELECT

    DISTINCT Remissierdetail.Scode2 AS oowncode

  FROM Remissierdetail remissierdetail

  WHERE Remissierdetail.Firmnumber   = 'KSH-000001'

  AND Remissierdetail.Scode2 !       = Rpad(' ',10)

  UNION

  SELECT

    DISTINCT Remissierdetail.Scode3 AS oowncode

  FROM Remissierdetail Remissierdetail

  WHERE remissierdetail.Firmnumber   = 'KSH-000001'

  AND remissierdetail.Scode3 !       = Rpad(' ',10)

select /* kshitij */ distinct coowncode

from Remissierdetail

unpivot 

(

  coowncode

  for node in (Scode, 

               Scode1, 

               Scode2, 

               Scode3)

) where  Firmnumber   = 'KSH-000001' and coowncode != Rpad(' ',10);