Q is the heater output right? I haven't spent more than 30 seconds thinking about it (so less time than writing this), but I don't really see any other way than getting the model output as time series and fitting your model against it to get your parameters. Your dependent variables are zone temperature and heater output (or Zone Air System Sensible Heating Energy maybe), your independent ones are your R and C.

Across a full year simulation, you should have more than enough datapoints to fit your model, but there's a chance your fit will be terrible, and you will probably need to downsample (aggregagate over longer periods of time).