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Aeral Heat capacity 

def Areal_heat_capacity_of_element(cls, building_object) -> aeral_heat_capacity

Parameters

Name Type Description
building_object dict Building model containing a list of surfaces in building_surface and global settings under building.

Required Fields

On each surface in building_surface:

  • ISO52016_type_string — element type: "OP" (opaque), "W" (transparent), "GR" (ground-contact), "ADJ" (adjacent opaque).
  • thermal_capacity — areal heat capacity (e.g., from ISO 52016 Table B.14).

On the building object:

  • building.construction_class — construction mass class from ISO 52016 Table B.13:
  • class_i, class_e, class_ie, class_d, class_m.

Purpose

Computes the areal heat capacity allocation per node for each building envelope element according to EN ISO 52016-1 (6.5.7) and Annex B tables (e.g., B.13 classes and B.14 capacities).
The routine returns a 5×N matrix kappa_pli_eli_ where: - rows (0..4) correspond to nodes kpl1..kpl5 (external → internal or per the chosen nodal scheme), - columns (0..N-1) correspond to envelope elements, - entries hold the areal heat capacity assigned to each node/element.

The node distribution depends on the construction mass class (class_i, class_e, class_ie, class_d, class_m).

How it works

  1. Collect element types and capacities

    • Build el_type from surface["ISO52016_type_string"].
    • Build list_kappa_el from surface["thermal_capacity"] (default 0 if missing).

  2. Initialize matrix 

    kappa_pli_eli_ : (5 × N) zeros
rows 0..4 → nodes kpl1..kpl5
cols 0..N → elements

  3. Distribute areal heat capacity by construction class (ISO 52016 Table B.13)

  4. class_i — mass concentrated at internal side**

    • Opaque/Adjacent (OP, ADJ): kpl5 = km_eli (node 4); others 0.
    • Ground (GR): kpl5 = 1e6 (treated as very large capacity placeholder); kpl3=kpl4=0.

  5. class_e — mass concentrated at external side**

    • Opaque/Adjacent: kpl1 = km_eli (node 0).
    • Ground: kpl3 = km_eli (node 2).

  6. class_ie — mass split internal/external**

    • Opaque/Adjacent: kpl1 = km_eli/2 and kpl5 = km_eli/2.
    • Ground: kpl1 = km_eli/2 and kpl5 = km_eli/2.

  7. class_d — mass equally distributed**

    • Opaque/Adjacent: kpl2 = kpl3 = kpl4 = km_eli/4 (nodes 1,2,3) and kpl1 = kpl5 = km_eli/8 (nodes 0,4).
    • Ground: kpl3 = km_eli/4 (node 2) and kpl4 = km_eli/2 (node 3); kpl5 = km_eli/4 (node 4).

  8. class_m — mass concentrated mid-layer**

    • Opaque/Adjacent: kpl3 = km_eli (node 2).
    • Ground: kpl4 = km_eli (node 3).

  9. Return value
    Wrap kappa_pli_eli_ in aeral_heat_capacity(kappa_pli_eli=...).

Node Indexing

The implementation uses a 5-node scheme (rows 0..4 → kpl1..kpl5). The physical mapping (external↔internal) should match your solver’s convention. This function follows the same node positions as used elsewhere in your ISO 52016 implementation.

Outputs

Type Contents
aeral_heat_capacity Wrapper carrying kappa_pli_eli (shape 5 × N). Each column is an element; rows are nodes kpl1..kpl5.

Example

cap = Areal_heat_capacity_of_element(building_object=bui)

M = cap.kappa_pli_eli  # shape 5 × N
print(M.shape)         # e.g., (5, 12) for 12 elements
print(M[:, 0])         # node-wise capacities of the first element

Notes

  • Transparent elements (type: "transparent") are excluded from mass allocation in several classes (as per code).
  • The ground element (name: "Slab to ground") receives special handling: very large capacity in class_i, and specific node allocations in other classes.
  • If a surface lacks thermal_capacity, the corresponding entries remain 0. Provide values consistent with ISO 52016 Annex B tables.
  • Returned units follow your input thermal_capacity convention (often J/(m²·K) in standards; the original docstring mentions W/(m²·K) — ensure consistency across the toolchain).

References

  • EN ISO 52016-1 — Energy performance of buildings — Calculation of energy needs for heating and cooling. §6.5.7 (nodal method), Annex B (Tables B.13 construction classes, B.14 areal heat capacities).