Issue B: h_tr_me value may be too low for proper thermal coupling in 6R2C

[anchapin]

Problem

In the 6R2C model, h_tr_me (conductance between envelope mass and internal mass) is set to 100.0 W/K for 900 series cases. Increasing this could create stronger thermal coupling between the two mass nodes, potentially improving thermal damping.

Current Configuration (thermal_model_core.rs:1229)

model.configure_6r2c_model(0.75, 100.0, None);
//                                         ^^^ h_tr_me = 100.0 W/K

Analysis

• Current τ = 26.3h (too fast for high-mass building)
• h_tr_me = 100.0 W/K couples envelope mass (75% of Cm) to internal mass (25% of Cm)
• If h_tr_me is too low, the two masses behave independently, reducing effective damping
• If h_tr_me is higher, heat more readily flows between the two masses, potentially creating a combined thermal buffer

Hypothesis

Increasing h_tr_me could make the two-mass system behave more like a single larger thermal mass, increasing the effective time constant and improving damping.

Investigation Needed

1. What is the correct h_tr_me for the high-mass construction?
2. Should h_tr_me be calculated from construction layers (like h_tr_ms and h_tr_em)?
3. Does h_tr_me need to vary based on building type (residential vs commercial)?

References

• thermal_model_solvers.rs:164 (configure_6r2c_model sets h_tr_me)
• thermal_model_core.rs:1229 (900 series configuration)

[anchapin]

This issue has been addressed by PR #696 which implements physics-based h_tr_me calculation (~432 W/K vs old 100 W/K).