Window A/C added Electric Cost

[Tim Jett]

I just purchased my first 4 unit apartment complex in Central NY and with summer approaching I have tenants starting to ask about being able to use window A/C units.  My lease states no window A/C units without written consent from the landlord. My concern is not with allowing the window units but merely the added cost of using a window A/C unit.  Any thoughts on the added cost; should I change a monthly fee (e.g. +$10 per unit), or not bother with it as it may not impact the utility cost that much... thoughts/ideas? Thanks