Mario Santos wrote

There are several reasons to require a convertible shopping center:
positioning and perception - open air sc’s have higher perceived attraction in mature markets because of their similarity with the more natural/less enclosed environment of traditional downtown shopping streets;
legal and urban constraints and gba/gla ratio – as is the case in Greece where building approvals are granted to total built area, not commercial or sales area (in Italy is the other way around, licenses are granted to sales area;
energy savings – having less volume of air to deal with clearly brings energy savings even if the tenants need to spend a little more that in an enclosed environment (although other variables should be looked at such as the heat gain along the glass shopfronts could be higher that the heat gain through the skylight because the total amount of glass in the skylight is smaller but, in any case, complementary solutions such as canopies should be considered)
The initial cost of the equipment to allow the roof to retract is an issue, though
ciao