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Aggregate surface - same orientation - 

def _aggregate_surfaces_by_direction(cls, building_object)

Inputs

Name Type Description
building_object dict A dictionary-like building model that must contain a key "building_surface", which is a list of surface definitions. Each surface should include ISO 52016 descriptors and physical properties (e.g., area, U-value, absorptance, etc.).

Purpose

This function aggregates (merges) multiple building surfaces that share the same orientation and ISO 52016 surface type into a single, equivalent surface.
The goal is to simplify the building model so that heat transmission and solar radiation terms can be computed on aggregated surfaces instead of on many small, redundant ones.

How It Works:

  1. Grouping (bucketing):
    Surfaces are grouped by:
  2. ISO52016_type_string (e.g., opaque wall, transparent window, etc.)
  3. ISO52016_orientation_string (e.g., N, S, E, W, HOR)
  4. type (transparent/opaque)

→ These three attributes form the aggregation key.

  1. Aggregation Rules:
  2. Additive fields:
    • area
    • thermal_capacity
  3. Area-weighted average fields:
    • u_value
    • g_value (only for transparent surfaces)
    • sky_view_factor
    • solar_absorptance
    • convective and radiative heat transfer coefficients (internal and external)

  4. Name field:
    The new aggregated surface name concatenates all original names (trimmed to 120 characters).

  5. Orientation Handling:
    A simplified numeric orientation is reattached to each aggregated surface:

  6. Default: {azimuth: 0, tilt: 90} (vertical)

  7. If ISO52016_orientation_string == "HOR" → {azimuth: 0, tilt: 0} (horizontal)

  8. Output:
    The method builds a new list of surfaces where each element represents one equivalent aggregated surface per direction and type.

Outputs

Type Description
dict A shallow copy of the input building_object, where building_surface has been replaced with a reduced list of aggregated surfaces.

Example

If the input building object contains three south-facing opaque walls:

Surface Name Type ISO52016 Type Orientation Area (m²) U-Value (W/m²K)
Wall_1 opaque Wall SV 10 0.30
Wall_2 opaque Wall SV 15 0.25
Wall_3 opaque Wall SV 5 0.40

After aggregation, the function returns one equivalent surface:

New Name Type Orientation Area (m²) U-Value (W/m²K)
Wall_1 + Wall_2 + Wall_3 opaque SV 30 0.30

where the U-value is computed as

\[ U_{agg} = \frac{\sum (U_i \times A_i)}{\sum A_i} \]

Example Usage 

building_object = ISO52016()._aggregate_surfaces_by_direction(building_object)

for surf in building_object["building_surface"]:
    print(f"{surf['ISO52016_orientation_string']} | {surf['type']} | Area = {surf['area']:.1f} m² | U = {surf['u_value']:.2f}")

Example output: 

HOR | opaque | Area = 130.0 m² | U = 2.20
NV | opaque | Area = 30.0 m² | U = 1.40
SV | opaque | Area = 30.0 m² | U = 1.40
EV | opaque | Area = 30.0 m² | U = 1.20
WV | opaque | Area = 30.0 m² | U = 1.20
HOR | opaque | Area = 100.0 m² | U = 1.60
EV | transparent | Area = 4.0 m² | U = 5.00
WV | transparent | Area = 4.0 m² | U = 5.00

Notes

  • Aggregates surfaces sharing type + ISO orientation.
  • Uses area-weighted averages for intensive properties.
  • Returns a clean, compact list of equivalent surfaces .

Advantages

  • Reduces model complexity for ISO 52016 energy balance computations.
  • Speeds up simulation and simplifies reporting.
  • Avoids double-counting of identical surfaces.
  • Ensures consistent area-weighted physical properties.

Limitations

  • Works only for dictionary-style building_object.
  • Orientation azimuth/tilt are currently placeholders, not exact averages.

  • Requires each surface to contain both:

    • ISO52016_type_string that is the typein the BUI dict
    • ISO52016_orientation_string that is the orientation in the BUI dict example:
            ..{
            "name": "Roof surface",
            "type": "adj",     # <-----
            "area": 130,
            "sky_view_factor": 1.0,
            "u_value": 2.2,
            "solar_absorptance": 0.4,
            "thermal_capacity": 741500.0,
            "orientation": {   # <-----
                "azimuth": 0,
                "tilt": 0
            },
            "name_adj_zone": None
        }