Others may disagree, but having only two packs and shutting one down to save money borders on gross negligence.
Gross negligence, yes indeed.
If one air conditioning pack (on a two pack aeroplane) were to be shutdown as a fuel saving measure, and then the other pack were to fail for some reason, re-starting the shutdown pack would be required.
Meanwhile, the cabin pressurization would be greatly affected....and if the intentionally shutdown pack was to
not re-start, a high dive is assured.
The fleet manager would not be amused, pilot dismissal time, I would think.
Regulatory action might well follow.