A (physicist) friend in Boulder said that incandescent light bulbs and "waste heat" get a bad rap. So what if incandescent light bulbs put off heat if you use them in the winter or at night, when your house could use the "waste" heat anyway? Heat is not wasted if you need it.
Our thermostat keeps track of how many total hours the furnace runs and we've been logging about 50 yours per winter. This doesn't sound like much, but the total includes only times when the furnace cycles on. The motor also runs the whole-house fan, which is hooked up to an electrostatic air filter. We run that any time of the year when dust or pollution is a problem. The motor ran for more than 50 hrs*15 years and we should have checked the system *before* we needed it. Live and learn.
We replaced most of the incandescent light bulbs in our house with fluorescent ones. Right now, I am really grateful for the few remaining incandescent bulbs in our home because of the welcome heat they put out. Our indoor temps have been hovering between 55-63 F this past week while outdoor temps have dipped as low as the upper 30s. At home, we dress like we do at night at camp.