> Sure you can leave the windows open, but that defeats the purpose. Modern home needs to be ventilated three times a day, that means opening all the windows in

> Sure you can leave the windows open, but that defeats the purpose. Modern home needs to be ventilated three times a day, that means opening all the windows in the morning, when you get home in the afternoon and before going to bed. How many people will remember to do that? I don't really understand your objection. in a leaky old style building without an effective moisture/thermal barrier, you don't get to choose whether ventilation is happening; it always is. with modern sealing, you can open the windows if you prefer fresh air, or you can enjoy much more efficient AC/heat if you don't. why couldn't you live in a modern home and just leave the windows open? it's easy to get a good draft going in any multifloor building with windows.