bph2-co2 1.0.4

Educational tool for co2_concentration simulations

Python library for education with tools for CO2 concentration simulations

Installation:

pip install bph2-co2==1.0.0

Example:

see also main.py

from bph_co2.solver import CO2_Simulation, ppm_to_mg_m3, mg_m3_to_ppm
from bph_co2.timeseries import Timeseries
from bph_co2.window import Window

try:
    import importlib.resources as pkg_resources
except ImportError:
    # Try backported to PY<37 `importlib_resources`.
    import importlib_resources as pkg_resources

from bph_co2.resources import Input_Data as case_data


if __name__ == '__main__':

    # load .csv files
    with pkg_resources.path(case_data, 'persons.csv') as path:
        persons_filename = path.__str__()

    with pkg_resources.path(case_data, 'internal_co2_source.csv') as path:
        internal_co2_source_filename = path.__str__()

    with pkg_resources.path(case_data, 'air_change_rate.csv') as path:
        air_change_rate_filename = path.__str__()

    with pkg_resources.path(case_data, 'window_state.csv') as path:
        window_state_filename = path.__str__()

    with pkg_resources.path(case_data, 'indoor_temperature.csv') as path:
        indoor_temperature_filename = path.__str__()

    with pkg_resources.path(case_data, 'outdoor_temperature.csv') as path:
        outdoor_temperature_filename = path.__str__()

    n_persons = Timeseries.from_csv(persons_filename, interpolation_scheme='previous')
    internal_co2_source = Timeseries.from_csv(internal_co2_source_filename, interpolation_scheme='linear')
    air_change_rate = Timeseries.from_csv(air_change_rate_filename, interpolation_scheme='linear')
    window_state = Timeseries.from_csv(window_state_filename, interpolation_scheme='previous')
    indoor_temperature = Timeseries.from_csv(indoor_temperature_filename, interpolation_scheme='linear')
    outdoor_temperature = Timeseries.from_csv(outdoor_temperature_filename, interpolation_scheme='linear')

    # create a window:
    window = Window(hight=1,
                    area=1,
                    state=window_state)

    sim = CO2_Simulation(name='test_simulation',
                         volume=51.48,
                         n_persons=n_persons,
                         emission_rate=27000,
                         internal_co2_source=internal_co2_source,
                         indoor_temperature=indoor_temperature,
                         outdoor_temperature=outdoor_temperature,
                         windows=[window],
                         air_change_rate=air_change_rate,
                         timestep=60,
                         t_end=26640)

    res = sim.calculate()

    res.plot()

Usage

Imports:

from src.bph_co2.solver import CO2_Simulation
from src.bph_co2.timeseries import Timeseries
from src.bph_co2.window import Window

CO2_Simulation:

• create a CO2_Simulation object. This is the base for running a simulation:

sim = CO2_Simulation(name='my_test_simulation')

The CO2_Simulation has the following parameters:

• name: the name of the CO2_Simulation; default is ‘Unnamed Simulation’

• volume: the volume of the simulated zone [m³]; default is 75

• n_persons: number of persons in the zone; default is 1 *

• emission_rate: CO2 emission_rate of a person in mg/h; default is 27000 mg/h;

• internal_co2_source: co2 emission rate of internal sources in mg/h; default is 0 *

• outdoor_temperature: outdoor temperature in °C; default is 10 °C *

• indoor_temperature: indoor temperature in °C; default is 20 °C *

• windows: windows of the zone; list of window-objects; default is []

• air_change_rate: air change rate in 1/h; default is 0.5 *

• c0i: initial CO2-concentration in the room/zone in ppm; default is 400

• c0e: initial outdoor CO2-concentration in ppm; default is 400

• timestep: simulation timestep [s]; default is 360

• t_end: end time of the simulation

All parameters can be set on initialization or afterwards. * Parameters can be Timeseries objects

• run a simulation:

res = sim.calculate()

• display simulation results:

  res.plot()

Timeseries Objects:

• A Timeseries handles data and returns a value / values for a time [s]. A Timeseries can handle static values (int, float, etc..), numpy arrays (first column has to be the time in [s]) or pd.Dataframes (index must be the time).

• Timeseries objects can interpolate Data in different ways. To specify interpolation scheme pass keyword interpolation_scheme with:

  • ‘linear’: linear interpolation

  • ‘previous’: closest previous value (for example for persons)

• Create a timeseries object with static value (integer):

n_persons = Timeseries(data=1)

• Create a timeseries object with np.array:

array = array = np.empty((2,100))
array[0,:] = np.arange(array.shape[1])
array[1,:] = np.random.rand(array.shape[1])
n_persons = Timeseries(data=array)

• Create a timeseries object with pd.Dataframe:

array = array = np.empty((2,100))
array[0,:] = np.arange(array.shape[1])
array[1,:] = np.random.rand(array.shape[1])

df = pd.DataFrame({'Time': array[0,:],
                   'n_persons': array[1,:]})
df.set_index('Time', inplace=True)

n_persons = Timeseries(data=array, interpolation_scheme='linear')

• Create a timeseries object from .csv file:

n_persons = Timeseries.from_csv('test.csv', interpolation_scheme='previous')

Windows:

In the Simulation windows can be added. Windows create additional air change in the zone dependent of the indoor- and outdoor-temperatures, the opening state and the geometry.

The window can have three states:

• 0: closed

• 1: tilted

• 2: opened

The window has the following parameters:

• hight: the hight of the window [m]; default is 1

• area: the area of the window [m²]; default is 1

• state: state of the window; 0: closed, 1: tilted; 2: opened; default is 0 (closed)

• c_ref: Austauschkoeffizient [m^0.5 / h * K^0.5], default is 100

• a_tilted: effective ventilation area for tilted window [m²]; default is calculated from the window geometry

• a_opened: effective ventilation area for opened window [m²]; default is calculated from the window geometry

• Create a window:

from src.bph_co2.window import Window

window_state = Timeseries.from_csv('window_state.csv', interpolation_scheme='previous')

window = Window(hight=1,
                area=1,
                state=window_state)

• Add window to the simulation:

The windows are specified as a list of window objects:

sim.windows = [window]