Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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

  1. Dec 5, 2015 #1
    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.
     
  2. jcsd
  3. Dec 5, 2015 #2

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    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.
     
  4. Dec 5, 2015 #3
    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.
     
  5. Dec 6, 2015 #4

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    If there is a layer of insulation you can probably ignore that and anything outside it.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook