In my family we have this thing where you don't shut all the curtains until everyone is home - so you have one window with the curtains open (or half open) and if it is dark you put a lamp in the window until all the family members get home in the evening.
So I have our kitchen blind half open (we don't have curtains) and a lamp on the windowsill until DH gets home.
DH says it is a nice idea (actually I don't think he'd even previously realised I do it until yesterday when we talked about it) but that in this very cold weather it will just make the flat cold, and I should shut all the blinds as soon as the sun goes down to preserve the heat.
AIBU to not be able to bring myself to do it, and to think it won't make the flat that cold
(yes I know, my family are bonkers, but it is just what we do. So there.)