if you have uninsulated walls or ceilings it can contribute to the over all problem. >> if the living space is being pressurized at different points in time through your heating system. case in point would be, fairly tight space with a fully operating supply duct system but a big hole in the return air duct means youure end up with more pressure in the house. it would force warm, moist air out through the nooks and cranies and putting the warm, moist air into the wall cavity. if it's cold you could get that. the lady says she changed her lights to use high efficiency fixtures let's talk about that. >> did you have a -- was it one of these styled lamps here with the -- we have a couple of different styles here. these come in different watages and sizes this is the typical. >> it's like that. >> sometimes they put a cover over them but it's one of these with a plastic cover. >> put a thing on the top and it will look like a light bulb. >> this is a benefit in that when you are screwing these in and out you do it by the base don't do it by the glass you twist the glass off the base then