If the fans are installed on the roof, they will need removal and placed somewhere else. Meaning no power and shock horror, closing the store.
Supermarkets did used to close for 5-12 days, depending on the size of the store to do a full refurb.
Now it takes 2 - 5 months of doing the work around customers and staff. This is frustrating for the staff and customers as things are moved a few times in the transition period. By the time you remember where things moved to - it has moved to somewhere else! The chillers and freezers don’t get replaced. The contents move.
I worked for a supermarket during its part refurb. The contractors were sawing MDF on the shop floor (closed off to everyone) and used various solvents. Had an asthma attack. This made me weak and got Covid for the second time a month later
On the first day I smelt MDF and solvents, I asked to be temporarily work in another store. That got rejected by the area manager. Had a change of store manager about 6 weeks later and he said that there was no risk assessment done for vulnerable people. Customers with asthma and other respiratory problems couldn’t shop. I dread to imagine what consequences that the supermarket chain got if I died from the asthma attack. As no risk assessment, my request to move stores whilst the work was being carried out, got rejected.
Yes the chillers and freezers weren’t replaced!
I’m sure that the cost of keeping the store open whilst doing a refit as close as to full whilst trading is more. Plus loss of sales as customers get fed up of finding stuff. Or going to another store for all their groceries.
In the days when supermarkets closed for 5-12 days, staff would either booked leave, work at another store or, those who can do hard physical work helped putting the stuff on the shelves etc. Or at least two of these options.