Hi
We clean smaller and different spaces and I work in square meters so always have to convert. I've done a rough calculation based on our cleaning routines and I imagine to a similar standard. I estimate about 12 hours to do that well once the routines and roles are established. Possibly more at first but usually we can't shave off more than 15 - 30 minutes of the total time after the first few cleans.
Have you looked into whether a different cleaning system could help? In other words, is it possible to be more production line oriented eg. one cleaner per task rather than one cleaner per area. I noticed that the more different tasks we have per person the longer it takes eg. if one person has to do a desk, a screen, a telephone, a bin, a bin liner - there's a lot of wasted time in changing movements, whereas one person doing only telephones another only desks their might be a time saving.
This might not be a welcome approach but with some team work and communication could mean a better result.
Grant