ladybug_comfort.collection.pmv module

Object for calculating PMV comfort from DataCollections.

class ladybug_comfort.collection.pmv.PMV(air_temperature, rel_humidity, rad_temperature=None, air_speed=None, met_rate=None, clo_value=None, external_work=None, comfort_parameter=None)[source]

Bases: _PMVnoSET

PMV 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.

  • 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 1.1 met (for seated, typing).

  • 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).

  • external_work – Data Collection of external work in met or a single external work value to be used for the whole analysis. If None, default is set to 0 met.

  • comfort_parameter – Optional PMVParameter object to specify parameters under which conditions are considered acceptable. If None, default will assume a PPD threshold of 10%, no absolute humidity constraints and a still air threshold of 0.1 m/s.

Properties:

  • air_temperature

  • rad_temperature

  • air_speed

  • rel_humidity

  • met_rate

  • clo_value

  • external_work

  • comfort_parameter

  • predicted_mean_vote

  • percentage_people_dissatisfied

  • operative_temperature

  • standard_effective_temperature

  • is_comfortable

  • thermal_condition

  • discomfort_reason

  • percent_comfortable

  • percent_uncomfortable

  • percent_neutral

  • percent_hot

  • percent_cold

  • percent_dry

  • percent_humid

  • humidity_ratio

  • adjusted_air_temperature

  • cooling_effect

  • heat_loss_conduction

  • heat_loss_sweating

  • heat_loss_latent_respiration

  • heat_loss_dry_respiration

  • heat_loss_radiation

  • heat_loss_convection

ToString()

Overwrite .NET ToString.

classmethod from_epw(epw, include_wind=True, include_sun=True, met_rate=None, clo_value=None, external_work=None, pmv_parameter=None)

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

Parameters:

  • epw – A ladybug EPW object from which the PMV 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).

  • external_work – Data Collection of external work in met or a single external work value to be used for the whole analysis. Default: 0 met.

  • pmv_parameter – Optional PMVParameter object to specify parameters under which conditions are considered acceptable. If None, default will assume a PPD threshold of 10%, no absolute humidity constraints and a still air threshold of 0.1 m/s.

Returns:

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

Usage:

from ladybug.epw import EPW
from ladybug_comfort.collection.pmv import PMV

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

# 12 values for the average SET in each month
print(pmv.standard_effective_temperature.average_monthly_per_hour().values)
property adjusted_air_temperature

Data Collection of air temperatures that have been adjusted by the SET model to account for the effect of air speed [C].

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 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 comfort_model

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

property comfort_parameter

PMV comfort parameters that are assigned to this object.

property cooling_effect

Data Collection of the cooling effect of the air speed in degrees Celsius.

This is the difference between the air temperature and the adjusted air temperature [C].

property discomfort_reason

Data Collection of integers noting the reason for discomfort according to the assigned comfort_parameter.

Values are one of the following:

  • -2 = too dry

  • -1 = too cold

  • 0 = comfortable

  • +1 = too hot

  • +2 = too humid

property external_work

Data Collection of the work done by the human subject in met.

property heat_loss_conduction

Data Collection of heat loss by conduction in [W].

property heat_loss_convection

Data Collection of heat loss by convection in [W].

property heat_loss_dry_respiration

Data Collection of heat loss by dry respiration in [W].

property heat_loss_latent_respiration

Data Collection of heat loss by latent respiration in [W].

property heat_loss_radiation

Data Collection of heat loss by radiation in [W].

property heat_loss_sweating

Data Collection of heat loss by sweating in [W].

property humidity_ratio

Data Collection of humidity ratio for the dry bulb and relative humidity.

property is_comfortable

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

property percent_dry

The percent of time that the thermal_condition neutral but it is too dry.

property percent_hot

The percent of time that the thermal_condition is hot.

property percent_humid

The percent of time that the thermal_condition neutral but it is too humid.

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 comfort_parameter.

property percentage_people_dissatisfied

Data Collection of percentage of people dissatisfied (PPD) for the input conditions.

Specifically, this is defined by the percent of people who would have a PMV beyond acceptable thresholds (typically <-0.5 and >+0.5). Note that, with the PMV model, the best possible PPD achievable is 5% and most standards aim to have a PPD below 10%.

property predicted_mean_vote

Data Collection of predicted mean vote (PMV) for the input conditions.

PMV is a seven-point scale from cold (-3) to hot (+3) that was used in comfort surveys of P.O. Fanger. Each interger value of the scale indicates the following:

  • -3 = Cold

  • -2 = Cool

  • -1 = Slightly Cool

  • 0 = Neutral

  • +1 = Slightly Warm

  • +2 = Warm

  • +3 = Hot

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 standard_effective_temperature

Data Collection of standard effective temperature (SET) for the input conditions.

These temperatures describe what the given input conditions “feel like” in relation to a standard environment of 50% relative humidity, <0.1 m/s average air speed, and mean radiant temperature equal to average air temperature, in which the total heat loss from the skin of an imaginary occupant with an activity level of 1.0 met and a clothing level of 0.6 clo is the same as that from a person in the actual environment.

property thermal_condition

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

Values are one of the following:

  • -1 = cold

  • 0 = netural

  • +1 = hot