ladybug_comfort.collection.pet module

Object for calculating PET comfort from DataCollections.

class ladybug_comfort.collection.pet.PET(air_temperature, rel_humidity, rad_temperature=None, air_speed=None, barometric_pressure=None, met_rate=None, clo_value=None, body_parameter=None)[source]

Bases: ComfortCollection

PET comfort DataCollection object.

Parameters:

  • air_temperature – Data Collection of air temperature values in Celsius.

  • rel_humidity – Data Collection of relative humidity values in % or a single relative humidity value to be used for the whole analysis.

  • rad_temperature – Data Collection of mean radiant temperature (MRT) values in degrees Celsius or a single MRT value to be used for the whole analysis. If None, this will be the same as the air_temperature.

  • air_speed – Data Collection of air speed values in m/s or a single air_speed value to be used for the whole analysis. If None, this will default to 0.1 m/s.

  • barometric_pressure – A value or data collection representing atmospheric pressure [Pa]. Default is to use air pressure at sea level (101,325 Pa).

  • met_rate – Data Collection of metabolic rate in met or a single metabolic rate value to be used for the whole analysis. If None, default is set to 2.4 met (for walking).

  • clo_value – Data Collection of clothing level in clo or a single clothing value to be used for the whole analysis. If None, default is set to 0.7 clo (for long sleeve shirt and pants).

  • body_parameter – Optional PETParameter object to specify the body properties of the human subject. The default attempts to model as average of a human body as possible.

Properties:

  • air_temperature

  • rad_temperature

  • air_speed

  • rel_humidity

  • barometric_pressure

  • met_rate

  • clo_value

  • body_parameter

  • physiologic_equivalent_temperature

  • core_body_temperature

  • skin_temperature

  • clothing_temperature

  • operative_temperature

  • is_comfortable

  • thermal_condition

  • pet_category

  • core_temperature_category

  • percent_comfortable

  • percent_uncomfortable

  • percent_neutral

  • percent_hot

  • percent_cold

ToString()

Overwrite .NET ToString.

classmethod from_epw(epw, include_wind=True, include_sun=True, met_rate=None, clo_value=None, body_parameter=None)[source]

Get a PET comfort object from the conditions within an EPW file.

Parameters:

  • epw – A ladybug EPW object from which the PET object will be created.

  • include_wind – Set to True to include the EPW wind speed in the calculation. Setting to False will assume a condition that is shielded from wind where the human experiences a very low wind speed of 0.1 m/s. If included, the wind speed at ground level will be assumed to be 2/3 times the meteorological wind speed in the EPW (usually at 10 meters). This follows the standard assumed for UTCI. (Default: True to include wind).

  • include_sun – Set to True to include the mean radiant temperature (MRT) delta from both shortwave solar falling directly on people and long wave radiant exchange with the sky. Setting to False will assume a shaded condition with MRT being equal to the EPW dry bulb temperature. When set to True, this calculation will assume no surrounding shade context, standing human geometry, and a solar horizontal angle relative to front of person (SHARP) of 135 degrees. A SHARP of 135 essentially assumes that a person typically faces their side or back to the sun to avoid glare. (Default: True to include sun).

  • met_rate – Data Collection of metabolic rate in met or a single metabolic rate value to be used for the whole analysis. Default: 2.4 met (walking at 1 m/s, which is the same assumption used in UTCI).

  • clo_value – Data Collection of clothing values rate in clo or a single clothing value to be used for the whole analysis. Default: 0.7 clo (long sleeve shirt and pants).

  • body_parameter – Optional PETParameter object to specify the body properties of the human subject. The default attempts to model as average of a human body as possible.

Returns:

An object with data collections of the PET results as properties.

Usage:

from ladybug.epw import EPW
from ladybug_comfort.collection.pet import PET

epw_file_path = './tests/epw/chicago.epw'
epw = EPW(epw_file_path)
pet = PET.from_epw(epw, include_wind=True, include_sun=True)

# 12 values for the average PET in each month
a = pet.physiologic_equivalent_temperature.average_monthly_per_hour().values
print(a)
property air_speed

Data Collection of air speed values in m/s.

property air_temperature

Data Collection of air temperature values in degrees C.

property barometric_pressure

Data Collection of the barometric pressure in Pa.

property body_parameter

PET body parameters that are assigned to this object.

property calc_length

The number of values in the Data Collections of this object.

property clo_value

Data Collection of clothing level of the human subject in clo.

  • 1 clo = Three-piece suit

  • 0.5 clo = Shorts + T-shirt

  • 0 clo = No clothing

property clothing_temperature

Data Collection of clothing temperature of the human subject.

property comfort_model

Return the name of the model to which the comfort datacollection belongs.

property core_body_temperature

Data Collection of core body temperature of the human subject.

property core_temperature_category

Data Collection of integers noting the classification of core body temperature.

Values are one of the following:

  • -2 = Hypothermia

  • -1 = Cold

  • 0 = Normal

  • 1 = Hot

  • 2 = Hyperthermia

property is_comfortable

Data Collection of integers noting whether the input conditions are acceptable according to the assigned body_parameter.

Values are one of the following:

  • 0 = uncomfortable

  • 1 = comfortable

property met_rate

Data Collection of metabolic rate in met.

  • 1 met = Metabolic rate of a resting seated person

  • 1.2 met = Metabolic rate of a standing person

  • 2 met = Metabolic rate of a walking person

property operative_temperature

Data Collection of operative temperature in degrees C.

property percent_cold

The percent of time that the thermal_condition is cold.

property percent_comfortable

The percent of time comfortable given by the assigned body_parameter.

property percent_hot

The percent of time that the thermal_condition is hot.

property percent_neutral

The percent of time that the thermal_condition is neutral.

property percent_uncomfortable

The percent of time uncomfortable given by the assigned body_parameter.

property pet_category

Data Collection of integers noting the thermal status on a nine-point scale.

Values are one of the following:

  • -4 = very strong/extreme cold stress

  • -3 = strong cold stress

  • -2 = moderate cold stress

  • -1 = slight cold stress

  • 0 = no thermal stress

  • +1 = slight heat stress

  • +2 = moderate heat stress

  • +3 = strong heat stress

  • +4 = very strong/extreme heat stress

property physiologic_equivalent_temperature

Data Collection of physiologic equivalent temperature (PET).

PET is a “feels like” temperature and is defined as the operative temperature of a reference environment that would cause the same physiological response in the human subject as the environment under study. That is, the same skin temperature and core body temperature.

property rad_temperature

Data Collection of mean radiant temperature (MRT) values in degrees C.

property rel_humidity

Data Collection of relative humidity values in %.

property skin_temperature

Data Collection of skin temperature of the human subject.

property thermal_condition

Data Collection of integers noting the thermal status of a subject according to the assigned body_parameter.

Values are one of the following:

  • -1 = cold

  • 0 = netural

  • +1 = hot