SET calculation

[FedericoTartarini]

Email from Charlie

I'm looking at the pythermalcomfort SET model and have a question. When I used input parameters of Clo=0.6, Met=1, RH=50%, Vel=0.1, and Tair=MRT, I thought I should get the result of SET=Tair. This is true when Tair=30, but above 30, SET is a bit higher and as Tair drops, SET diverges below Tair.

Some preliminary results

I run the following code and this is what I get. I am not sure what it causing the anomaly around 37.5C.

for t in range(22, t_max, 1):
# calculate the SET
two_nodes(tdb=t, tr=t, v=0.1, rh=50, met=1, clo=0.6)

Full Python code

from pythermalcomfort.models import two_nodes
import pandas as pd
import matplotlib.pyplot as plt

t_max = 44
array_results = []
for t in range(22, t_max, 1):
    # calculate the SET
    results = two_nodes(tdb=t, tr=t, v=0.1, rh=50, met=1, clo=0.6)
    results['t'] = t
    array_results.append(results)

df = pd.DataFrame(array_results)

df.plot(x="t", y="_set", c="k", lw=2)
plt.plot(range(22, t_max, 1), range(22, t_max, 1), c="r", lw=2)
plt.xlabel("Temperature (°C)")
plt.ylabel("SET (°C)")
plt.title("SET vs Temperature")
plt.grid(True)
# remove the legend
plt.legend().remove()
plt.show()