# coding=utf-8
"""Parameters for specifying acceptable thermal conditions using the PMV model."""
from __future__ import division
import re
from ._base import ComfortParameter
from ..pmv import ppd_threshold_from_comfort_class
[docs]class PMVParameter(ComfortParameter):
"""Parameters of PMV comfort.
Args:
ppd_comfort_thresh: A number between 5 and 100 that represents the upper
threshold of PPD that is considered acceptable.
Default is 10, which characterizes most buildings in the ASHRAE-55 and
EN-15251 standards.
humid_ratio_upper: A number between 0 and 1 indicating the upper limit of
humidity ratio that is considered acceptable. Default is 1 for
essentially no limit.
humid_ratio_lower: A number between 0 and 1 indicating the lower limit of
humidity ratio considered acceptable. Default is 0 for essentially
no limit.
still_air_threshold: The air speed threshold in m/s at which the standard
effective temperature (SET) model will be used to correct for the
cooling effect of elevated air speeds.
Default is 0.1 m/s, which is the limit according to ASHRAE-55.
Properties:
* ppd_comfort_thresh
* humid_ratio_upper
* humid_ratio_low
* still_air_threshold
"""
_model = 'Predicted Mean Vote'
__slots__ = ('_ppd_thresh', '_hr_upper', '_hr_lower', '_still_thresh')
def __init__(self, ppd_comfort_thresh=None, humid_ratio_upper=None,
humid_ratio_lower=None, still_air_threshold=None):
"""Initialize PMV Parameters."""
self.ppd_comfort_thresh = \
ppd_comfort_thresh if ppd_comfort_thresh is not None else 10
self._hr_upper = humid_ratio_upper if humid_ratio_upper is not None else 1
self._hr_lower = humid_ratio_lower if humid_ratio_lower is not None else 0
self._still_thresh = \
still_air_threshold if still_air_threshold is not None else 0.1
assert 0.008 <= self._hr_upper <= 1, \
'humid_ratio_upper must be between 0.008 and 1. Got {}'.format(
self._hr_upper)
assert 0 <= self._hr_lower <= 0.005, \
'humid_ratio_lower must be between 0 and 0.005. Got {}'.format(
self._hr_lower)
assert 0 <= self._still_thresh, \
'still_air_threshold must be greater than 0. Got {}'.format(
self._still_thresh)
[docs] @classmethod
def from_dict(cls, data):
"""Create a PMVParameter object from a dictionary.
Args:
data: A PMVParameter dictionary in following the format below.
.. code-block:: python
{
'type': 'PMVParameter',
'ppd_comfort_thresh': 20,
'humid_ratio_upper': 0.12,
'humid_ratio_lower': 0,
'still_air_threshold': 0.2
}
"""
assert data['type'] == 'PMVParameter', \
'Expected PMVParameter dictionary. Got {}.'.format(data['type'])
ppd_comfort_thresh = data['ppd_comfort_thresh'] if \
'ppd_comfort_thresh' in data else 10
humid_ratio_upper = data['humid_ratio_upper'] if \
'humid_ratio_upper' in data else 1
humid_ratio_lower = data['humid_ratio_lower'] if \
'humid_ratio_lower' in data else 0
still_air_threshold = data['still_air_threshold'] if \
'still_air_threshold' in data else 0.1
return cls(ppd_comfort_thresh, humid_ratio_upper, humid_ratio_lower,
still_air_threshold)
[docs] @classmethod
def from_string(cls, pmv_parameter_string):
"""Create an PMVParameter object from an PMVParameter string."""
str_pattern = re.compile(r"\-\-(\S*\s\S*)")
matches = str_pattern.findall(pmv_parameter_string)
par_dict = {item.split(' ')[0]: item.split(' ')[1] for item in matches}
ppd_threshold = float(par_dict['ppd-threshold']) \
if 'ppd-threshold' in par_dict else None
hr_upper = float(par_dict['hr-upper']) \
if 'hr-upper' in par_dict else None
hr_lower = float(par_dict['hr-lower']) \
if 'hr-lower' in par_dict else None
still_air_threshold = float(par_dict['still-air-threshold']) \
if 'still-air-threshold' in par_dict else None
return cls(ppd_threshold, hr_upper, hr_lower, still_air_threshold)
@property
def ppd_comfort_thresh(self):
"""The threshold of the percentage of people dissatisfied (PPD) beyond which
the conditions are not acceptable. The default is 10%.
"""
return self._ppd_thresh
@ppd_comfort_thresh.setter
def ppd_comfort_thresh(self, ppd):
assert 5 <= ppd <= 100, \
'ppd_comfort_thresh must be between 5 and 100. Got {}'.format(ppd)
self._ppd_thresh = ppd
@property
def humid_ratio_upper(self):
"""A number representing the upper boundary of humidity ratio above which conditions
are considered too humid to be comfortable. The default is set to 0.03 kg
wather/kg air.
"""
return self._hr_upper
@property
def humid_ratio_lower(self):
"""A number representing the lower boundary of humidity ratio below which conditions
are considered too dry to be comfortable. The default is set to 0 kg wather/kg
air.
"""
return self._hr_lower
@property
def still_air_threshold(self):
"""A number representing the wind speed beyond which the formula for Standard
Effective Temperature (SET) is used to determine PMV/PPD (as opposed to Fanger's
original equation). The default is set to 0.1 m/s.
"""
return self._still_thresh
[docs] def set_ppd_comfort_thresh_from_comfort_class(self, comfort_class):
"""Set the PPD threshold given the EN-15251 comfort class."""
self.ppd_comfort_thresh = ppd_threshold_from_comfort_class(comfort_class)
[docs] def is_comfortable(self, ppd, humidity_ratio=0):
"""Determine if conditions are comfortable or not.
Values are one of the following:
* 0 = uncomfortable
* 1 = comfortable
"""
return 1 if (ppd <= self._ppd_thresh and humidity_ratio >= self._hr_lower and
humidity_ratio <= self._hr_upper) else 0
[docs] def thermal_condition(self, pmv, ppd):
"""Determine whether conditions are cold, neutral or hot.
Values are one of the following:
* -1 = cold
* 0 = netural
* +1 = hot
"""
if ppd >= self._ppd_thresh:
return 1 if pmv > 0 else -1
else:
return 0
[docs] def discomfort_reason(self, pmv, ppd, humidity_ratio=0):
"""Determine the reason why conditions are comfortable or not.
Values are one of the following:
* -2 = too dry
* -1 = too cold
* 0 = comfortable
* +1 = too hot
* +2 = too humid
"""
if ppd >= self._ppd_thresh:
return 1 if pmv > 0 else -1
elif humidity_ratio < self._hr_lower:
return -2
elif humidity_ratio > self._hr_upper:
return 2
else:
return 0
[docs] def to_dict(self):
"""PMVParameter dictionary representation."""
return {
'type': 'PMVParameter',
'ppd_comfort_thresh': self.ppd_comfort_thresh,
'humid_ratio_upper': self.humid_ratio_upper,
'humid_ratio_lower': self.humid_ratio_lower,
'still_air_threshold': self.still_air_threshold
}
def __copy__(self):
return PMVParameter(self.ppd_comfort_thresh, self.humid_ratio_upper,
self.humid_ratio_lower, self.still_air_threshold)
def __repr__(self):
"""PMV comfort parameters representation."""
return '--ppd-threshold {} --hr-upper {} ' \
'--hr-lower {} --still-air-threshold {}'.format(
self._ppd_thresh, self._hr_upper, self._hr_lower, self._still_thresh)