I am living in a house with many large windows.  My boyfriend and I often don't get home until 10:00pm.  I was wondering if it is more efficient to leave the curtains closed all day or leave them open and close them at 10.  In addition to the curtains, we are planning to put plastic on the windows and we don't have curtains on all of the windows.

I suppose that depends on what it is you want the curtains to do. Are they on the south side or north side of the house? Do you want them to block out sunlight to keep your interior from getting too hot? Do you want them to keep in heat so your interior doesn't get too cold?

From what I've read, curtains don't do much to retain heat. For that, you want thermal shutters with weatherstripping around them to seal the window at night.

I know that to keep a house cool in the summer they say it's best to block the sun before it gets through the glass– things like blinds, shades, etc that are inside absorb the sun and radiate the heat into the house. I would think the same would be true in winter, though you might not gain as much in the day as you would with drapes open, since some of the heat can radiate back through the glass and with them open the sun penetratets deeper into the room.

its true curtains add advantages in home interior is very good i like all type of of curtains