# How do you calculate total heat capacity for a house/wall?

I was wondering how I might be able to calculate the total heat capacity for a house given the individual heat capacities of the components.

For example, if I take a given wall and break it down into its components for a lumped parameter model, I'll have some thermal capacitances in in parallel. In the circuit analogy, they would be drawn as capacitors. Do these add like capacitors in a circuit would (algebraically for parallel, inversely for series)? I don't imagine I'd have any capacitances in series because each component has an RC pair in parallel...

I realize that a lumped parameter model is not realistic for a wall (the Biot # would be huge), however I'm more interested in the differential equations application of this.

Thanks.

CWatters
Homework Helper
Gold Member
Do you really mean heat capacity or thermal resistance/conductance?

I doubt its as simple as parallel vs series. For example thermal mass on the outside might not contribute as much as thermal mass on the inside.

I really mean heat capacity; I'm trying to get a very crude approximation of the time constant for the room. Essentially I'm trying to model it as a lumped parameter system with resistance and capacitance. The problem is that I've got series and parallel components due to the construction of the wall. I was thinking I might be able to simplify it down further, but it would seem that I've got to treat each RC pair as its own system within a larger system.

I suppose this is why most people use computational thermal mechanics programs for stuff like this.

CWatters
Homework Helper
Gold Member
If there is a layer of insulation you can probably ignore that and anything outside it.