Still think its resi, but might be close. This isn't a go at you though, you seem adamant is comi, and I think resi, so would be interested to see what everyone thinks.
From the 2001 cencus
There are a total of 22,539,000 households in England and Wales
The average number of rooms per household is 5.34.
that's 120,358,260 windows if there is one in every room and thats just England and Wales.
The population of the United Kingdom grew steadily over the last decade of the 20th Century to stand at 58,789,194 on Census Day 2001.