If it is a part of service condition and meant to achieve work-life balance, organisation can schedule compulsory leave for all to avail at the same period. It is pro -employee intervention and I do not see anything wrong in it.
Only thing is , such a leave can be over and above an employee may want to avail of some other period in the year.
Though the concept looks appropriate, it can't be judged on the consequences. If the office is closed it's generally taken as 'paid holiday'. Since there is no tag attached like 'lay off', lock out, shut down for want of orders or raw material' etc. the event can be taken as 'paid holiday' which we can't either affirm or deny without knowing the ground realities. And whether these 'closed' days will be debited to employees' PL a/c, I think you should make it clear from the owner himself and act accordingly.
Except on 'health' issues no employer can send an employee on 'leave'. Moreover we have no information about the nature of your duty, is't some much stressful/ or polluted warranting compulsory shut down of the unit itself ?
Is't for the first time such closure is resorted to? what the other employees say or react to this? I think if there is no salary cut you people can accept is gladly.