Heat Loss and Electric Bill?

I would like to figure out how much it would cost to heat my apartment with electricity rather than gas. As a test I have a thermometer and a hair dryer, and can see how long it takes to heat my room by 5 degrees. If I assume a perfect no loss environment, and ignore the heat capacity of the furniture and items in the room, and assume only the volume of air, I can calculate how many watts per degree. (BTW, my gas bill was $220.00 last month.)


Is ignoring furniture, books, clothes, etc. going to cause more than 5% error?


What equations would I use if I now add in heat loss through the window? I need to come up with a model or set of equations that uses the outside temp.


Thanks!Heat Loss and Electric Bill?
If you wanted to calculate the heat loss in a room, the easiest way would be to heat it up and then let it cool down. The heat flow is proportional to the temperature difference, and the temperature is proportional to the contained heat, so that you will get an exponential curve to fit your temperature data to.





You could try to measure heat flux through the window as well, but I wouldn't necessarily recommend it. If it's really absolutely necessary to know this datum in particular, measure the temperature relaxation curve above in two circumstances: (1) with the window, and (2) covering the window with sheets and other good insulators. If you can spot a difference in the temperature relaxations, you can account for the relative flux of one over the other.