Close a Door If You Wish
Open a Window Day is for those with windows to open. "Thank you, Captain Obvious," yes, but not everyone has openable windows or lives in a place where opening windows is a wise thing.
We're specifically talking about house (living place) windows here. This is not about car (vehicle) windows or Microsoft Windows windows.
We could open a window today but this year will likely choose not to celebrate because it's about 88 degrees outside, very humid, and the air conditioning is on.
Tomorrow we'll likely celebrate it belatedly since the forecast (2016) is for 70s and sun.
Generally speaking, opening windows is good because you can let fresh air in and you can hear the birds outside.
Generally speaking, opening windows is bad because you hear the neighbors' dogs yapping at nothing, large trucks rumbling past, and lawnmowers and other yard equipment being put to excessive use.
It should be a crime to use a leaf blower for anything else.