Untested

[% BLOCK THE_SCOPE_OF_ROPE;
   FOREACH hash IN results.$key;
     SET open = hash.open IF hash.open;
     SET closed = hash.closed IF hash.closed;
   END;
%]
<td>[% open   | html %]</td>
<td>[% closed | html %]</td>
[% END %]
[download]

Though you probably want to use  IF hash.exists('open');