Recently moved into a new build. Everything is good but what's annoying me are the massive 6 inch diameter vents in every room of the house. I'm mostly annoying at the fact and can hear everything that is happening outside. I can even hear the baby crying next door in my house even though it's detached. Now the winter is setting in I'm noticing the house doesnt stay warm for that long even though is is supposed to be this fantastic A rated out. The heat obviously just goes out the vent.
Is there anything to be done with these? I've asked around and most people say you can't block them as could lead to damp which is fair enough I guess. I was thinking about shoving in some insulation and I also have small vents on the windows I could leave open instead. Any other suggestions? I don't want to seal up with expanding foam.
I've attached picture of the vent and the cover which slides over but makes feck all difference.