Predicted Mean Vote Index PMV

Overview

Engineering reference data for Predicted Mean Vote Index PMV in miscellaneous.

Key Formulas

Unit Conversion

$y = x \cdot k$

Multiply by conversion factor.

Linear Interpolation

$y = y_1 + \frac{(x - x_1)(y_2 - y_1)}{x_2 - x_1}$

Estimate between two known points.

Percentage

$p = \frac{\text{part}}{\text{whole}} \times 100\%$

Part as fraction of whole.

Variables

PMV Thermal Sensation Scale

The Predicted Mean Vote (PMV) index is based on the ASHRAE thermal sensation scale, which rates subjective thermal feeling from +3 to -3:

• *+3: Hot
• *+2: Warm
• *+1: Slightly warm
• *0: Neutral
• *-1: Slightly cool
• *-2: Cool
• *-3: Cold

PMV Formula

The PMV index, as expressed by P.O. Fanger, is calculated using the following relationship:

$$\text{PMV} = (0.303 \cdot e^{-0.036M} + 0.028) \cdot L$$

Where:

• $\text{PMV}$ is the Predicted Mean Vote Index.
• $M$ is the metabolic rate.
• $L$ is the thermal load, defined as the difference between internal heat production and the heat loss to the actual environment for a person at comfort skin temperature and with evaporative heat loss by sweating at the actual activity level.

PPD Index Explanation

The Predicted Percentage Dissatisfied (PPD) index is a quantitative measure of the thermal comfort of a group of people at a particular thermal environment.

An important engineering property of this model is that at least approximately 5% of people in a group will be dissatisfied with the thermal environment, even when the PMV is equal to 0 (neutral conditions). This establishes a practical lower limit for thermal dissatisfaction in any occupied space.

References

• Original Source