You still don't understand. No, watts are NOT tied to seconds. Watts are not tied to time AT ALL!! If a wall is losing heat at a specific rate of 500 watts based on your calculation at a specific temperature and that temperature stays the same for an hour then you have 500 Wh of heat. The calculation is based on that specific point in time. My house loses heat at a rate between 285 and 300BTU/hr based on my calculations based on furnace runtime on different days when temperature was between 10 and 20f. I'll use 300BTU/hr for calculations sake which is 88 watts multiplied by the temperature difference(in F) between outside and inside. If its 10f outside and 70 inside that is 6.4 kilowatts. If I have no sun and it stays that temperature for 8 hours, that would be 51.2kWh.
If you still don't get it, please research the definition of watts and kilowatthours. The reason why the calculation doesn't have Wh in it is because the calculation doesn't factor the difference over a period of time. The calculation you are trying to make does factor in time though since you are putting it to a time frame, therefore the result will be in kWh. ...unless you took the total time of the winter, the heating months, or something similar and then divided it by that amount of time to come up with an average heat loss for that time period. It doesn't make for a very useful number for 21359kWh would be an average heat loss of 365 watts over the period of a year, that number isn't useful though. Figuring out that number over the period of a day, multiple days, weekly, or a monthly basis might be useful considering your thermal mass would reduce the size of any auxiliary heating device on very cold or cloudy days significantly.
