import numpy as np
from pythermalcomfort.models import pmv
[docs]def e_pmv(tdb, tr, vr, rh, met, clo, e_coefficient, wme=0, **kwargs):
"""Returns Adjusted Predicted Mean Votes with Expectancy Factor (ePMV).
This index was developed by Fanger, P. O. et al. (2002). In non-air-
conditioned buildings in warm climates, occupants may sense the warmth as
being less severe than the PMV predicts. The main reason is low
expectations, but a metabolic rate that is estimated too high can also
contribute to explaining the difference. An extension of the PMV model that
includes an expectancy factor is introduced for use in non-air-conditioned
buildings in warm climates [26]_.
Parameters
----------
tdb : float, int, or array-like
dry bulb air temperature, default in [°C] in [°F] if `units` = 'IP'
tr : float, int, or array-like
mean radiant temperature, default in [°C] in [°F] if `units` = 'IP'
vr : float, int, or array-like
relative air speed, default in [m/s] in [fps] if `units` = 'IP'
Note: vr is the relative air speed caused by body movement and not the air
speed measured by the air speed sensor. The relative air speed is the sum of the
average air speed measured by the sensor plus the activity-generated air speed
(Vag). Where Vag is the activity-generated air speed caused by motion of
individual body parts. vr can be calculated using the function
:py:meth:`pythermalcomfort.utilities.v_relative`.
rh : float, int, or array-like
relative humidity, [%]
met : float, int, or array-like
metabolic rate, [met]
clo : float, int, or array-like
clothing insulation, [clo]
Note: The activity as well as the air speed modify the insulation characteristics
of the clothing and the adjacent air layer. Consequently, the ISO 7730 states that
the clothing insulation shall be corrected [2]_. The ASHRAE 55 Standard corrects
for the effect of the body movement for met equal or higher than 1.2 met using
the equation clo = Icl × (0.6 + 0.4/met) The dynamic clothing insulation, clo,
can be calculated using the function
:py:meth:`pythermalcomfort.utilities.clo_dynamic`.
e_coefficient : float
expectacy factor
wme : float, int, or array-like
external work, [met] default 0
Other Parameters
----------------
units : {'SI', 'IP'}
select the SI (International System of Units) or the IP (Imperial Units) system.
limit_inputs : boolean default True
By default, if the inputs are outsude the standard applicability limits the
function returns nan. If False returns pmv and ppd values even if input values are
outside the applicability limits of the model.
The ISO 7730 2005 limits are 10 < tdb [°C] < 30, 10 < tr [°C] < 40,
0 < vr [m/s] < 1, 0.8 < met [met] < 4, 0 < clo [clo] < 2, and -2 < PMV < 2.
Returns
-------
pmv : float, int, or array-like
Predicted Mean Vote
Examples
--------
.. code-block:: python
>>> from pythermalcomfort.models import a_pmv
>>> from pythermalcomfort.utilities import v_relative, clo_dynamic
>>> tdb = 28
>>> tr = 28
>>> rh = 50
>>> v = 0.1
>>> met = 1.4
>>> clo = 0.5
>>> # calculate relative air speed
>>> v_r = v_relative(v=v, met=met)
>>> # calculate dynamic clothing
>>> clo_d = clo_dynamic(clo=clo, met=met)
>>> results = e_pmv(tdb, tr, v_r, rh, met, clo_d, e_coefficient=0.6)
>>> print(results)
0.51
"""
default_kwargs = {"units": "SI", "limit_inputs": True}
kwargs = {**default_kwargs, **kwargs}
met = np.array(met)
_pmv = pmv(tdb, tr, vr, rh, met, clo, wme, "ISO", **kwargs)
met = np.where(_pmv > 0, met * (1 + _pmv * (-0.067)), met)
_pmv = pmv(tdb, tr, vr, rh, met, clo, wme, "ISO", **kwargs)
return np.around(_pmv * e_coefficient, 2)