honeybee_energy.ventcool.crack module

Definition of surface crack for multizone airflow.

class honeybee_energy.ventcool.crack.AFNCrack(flow_coefficient, flow_exponent=0.65)

Bases: object

Airflow leakage through surface due to cracks or porous surface material.

Note that this whole class only has bearing on the simulation when the Model that the AFNCrack is a part of has its ventilation_simulation_control set for MultiZone air flow, thereby triggering the use of the AirflowNetwork.

Parameters

• flow_coefficient –

  A number in kg/s-m at 1 Pa per meter of crack length at the conditions defined in the ReferenceCrack condition; required to run an AirflowNetwork simulation. Some common values for this coefficient from the DesignBuilder Cracks template include the following:

  • 0.00001 - Tight low-leakage external wall

  • 0.001 - Tight, low-leakage internal wall

  • 0.0004 - Poor, high-leakage external wall

  • 0.019 - Poor, high-leakage internal wall

• flow_exponent – An optional dimensionless number between 0.5 and 1 used to calculate the crack mass flow rate; required to run an AirflowNetwork simulation. This value represents the leak geometry impact on airflow, with 0.5 generally corresponding to turbulent orifice flow and 1 generally corresponding to laminar flow. The default of 0.65 is representative of many cases of wall and window leakage, used when the exponent cannot be measured. (Default: 0.65).

Properties:

• flow_coefficient

• flow_exponent

ToString()

Overwrite .NET ToString.

duplicate()

Get a copy of this object.

classmethod from_dict(data)

Create a AFNCrack object from a dictionary.

Parameters

data – A AFNCrack dictionary following the format below.

{
"type": "AFNCrack",
"flow_coefficient": 0.01 # coefficient at reference crack
"flow_exponent": 0.65 # exponent for the surface crack
}

lock()

to_dict()

AFNCrack dictionary representation.

unlock()

property flow_coefficient

Get or set the air mass flow coefficient defined at the reference crack.

property flow_exponent

Get or set the air mass flow exponent for the surface crack.