By DWIGHT BARNETT, Scripps Howard News Service

Q: I live in Alaska and I recently noticed that my windows have moisture on the inside of them. Can it be that it is so cold outside and warm inside the house? The house is only 3 years old and has a five-star energy rating.

Q: I am thinking about replacing the ducting in my house and adding a zoning system. I have spoken with several contractors and have received differing opinions and ridiculously different prices. Can you help me figure out what I need?

Q. How can I tell if the fireplace doors I have in my new (70-year-old) house are ceramic or tempered glass?

A. The doors are most likely made of mica, a natural mineral found in India, China, the United States, South Korea and Canada.

Q: I recently had an air-conditioning system installed and they converted the air handler to a vertical up-flow front return. They left the filter exposed, and after reading your article about getting the proper treatment for sick buildings, my concern is that because the filter is exposed it can pick up more mold and circulate it throughout my condo.

Q: I need to call someone to clean my air conditioner and whatever else is included. Who or what type of company performs this job? Also, what should I be having done to my unit and/or inside ducts and furnace? I want to make sure there is no mold or anything when this has been performed. -- Connie.

Q: I need to call someone to clean my air conditioner and whatever else is included. Who or what type of service company performs this job? Also, what should I be having done to my unit and/or inside ducts and furnace? I want to make sure there is no mold or anything when this has been performed.

Q: I own a house that was built in 1999 and am concerned about the number of drywall screws that have started to protrude from the walls and ceiling. Several of the screws have "popped" off the mud or spackle that was used to cover them, and, from what I can tell, they appear to have rusted.

Q: I have a three-level townhouse. Lately, I've seen moisture in the ceiling of the downstairs level, near a duct. After cutting a hole in a closet wall to see the ductwork, I saw that my ducts (about 30 years old) had insulation around them but no moisture barrier.

Q: I live on a fixed income, so I try to not spend so much on electric bills. What I do is turn off my refrigerator at night, then plug it in again the next morning. My electric bills are a little less than before. Is this a good idea?

A: I also received a question concerning an electric water heater and whether it should be turned off when not in use.

Q: I've tried several things to remove old wallpaper. I'm guessing the people who set it up were poorly skilled. Because of that, I put different wallpaper over that, but it's just making more of a problem. How can I remove old wallpaper without causing damage to the wall?