PMV – details

I’ve found a nice PMV & PPD calculator right here.

For those, who has nothing to do in the evenings, I enclose the math as well.

 

 

PMV = (0,303e^-2,100*M + 0,028)*[(M-W)- H – E_c – C_res – E_res] (1)

where the different terms represent, respectively:

• M – the metabolic rate, in Watt per square meter (W/m2 );
• W – the effective mechanical power, in Watt per square meter (W/m2 );
• H – the sensitive heat losses;
• E_c – the heat exchange by evaporation on the skin;
• C_res – heat exchange by convection in breathing;
• E_res – the evaporative heat exchange in breathing.

In equation 1, the terms H, E_c, C_res, and H_res, correspond to the heat exchange between the body and the surrounding environment and are calculated from the following equations:

H = 3,96*10^-8*f_cl*[(t_cl+273)⁴ – (t_r+273)⁴ ] – f_cl*h_c*(t_cl-t_a) (2)

Ec = 3,05*10^-3*[5733 – 6,99*(M-W)-p_a]-0,42*[(M-W)-58,15] (3)

Cres = 0,0014*M*(34-t_a) (4)

Eres = 1,7*10^-5*M*(5867-p_a) (5)

where:

• I_cl is the clothing insulation, in square meters Kelvin per watt (m² K/W);
• f_cl is the clothing surface area factor; ta is the air temperature, in degrees Celsius (°C);
• t_r is the mean radiant temperature, in degrees Celsius (°C);
• v_ar is the relative air velocity, in meters per second (m/s);
• p_a is the water vapor partial pressure, in Pascal (Pa);
• t_cl is the clothing surface temperature, in degrees Celsius (°C).