I'll to preface this with saying that the output is not EXACTLY in the format that you want...But it is readable, and the program does appear to work. I'm just a simple Perl hacker...With a little bit of elbow grease (which I don't necessarily know how to apply), this could become what you're looking for.

#!/usr/bin/perl -wT

use strict;
use Data::Dumper;

my $roomtype;
my $dim;
my $count;
my %output;

while (<DATA>) {
  chomp;

  # If the first character of the input is a letter, then we're on a n
+ew
  # room type
  if (/^[a-zA-Z]+/) {
    $roomtype = $_;
        $dim = undef;
  } else {
    $dim = join('_', split / /);
  }

  if (defined($roomtype) && defined($dim)) {
    my $room = $roomtype . '_' . $dim;

    if (defined($output{$room})) {
      my $cur = $output{$room};
      $cur++;
      $output{$room} = $cur;
    } else {
      $output{$room} = 1;
    }
  }
}

my $data = Data::Dumper->new([\%output], [qw/*output/]);

print $data->Dump;

__DATA__
office 1
120 120
120 120
140 135
155 135
120 120
bedroom 2
100 75
100 75
120 180
[download]

And the output:

$ ./window.pl
%output = (
            'bedroom 2_120_180' => 1,
            'office 1_120_120' => 3,
            'bedroom 2_100_75' => 2,
            'office 1_155_135' => 1,
            'office 1_140_135' => 1
          );
[download]