Advanced Climate PMV Form
Example Data Table
| Scenario |
Air C |
Radiant C |
Humidity % |
Speed m/s |
Met |
Clo |
PMV |
PPD % |
| Office neutral |
24 |
24 |
50 |
0.10 |
1.20 |
0.50 |
-0.214 |
5.95 |
| Cool room |
20 |
20 |
45 |
0.10 |
1.20 |
0.70 |
-0.915 |
22.67 |
| Warm climate |
28 |
29 |
60 |
0.20 |
1.20 |
0.50 |
1.042 |
27.93 |
| Active indoor work |
22 |
24 |
50 |
0.30 |
1.60 |
0.80 |
0.310 |
7.00 |
Formula Used
The calculator uses the Fanger heat balance method. It estimates Predicted Mean Vote from body heat production and heat losses.
PMV = thermal sensation coefficient × internal heat load
PPD = 100 - 95 × exp(-0.03353 × PMV⁴ - 0.2179 × PMV²)
The internal heat load includes skin diffusion, sweating, breathing, radiation, and convection. Clothing insulation changes the clothing surface temperature. Air speed changes the convective heat transfer coefficient.
How To Use This Calculator
- Enter the room or climate zone name.
- Add air temperature and mean radiant temperature in Celsius.
- Enter relative humidity as a percent.
- Add measured air speed in meters per second.
- Enter metabolic rate and clothing insulation.
- Set an optional PMV target range.
- Press the calculate button.
- Download the CSV or PDF report when needed.
Understanding PMV In Climate Comfort
Predicted Mean Vote helps describe how people may feel in a room or work zone. It uses heat balance. The method checks air temperature, mean radiant temperature, humidity, air speed, clothing, and activity. A value near zero suggests neutral comfort. Negative values suggest cool feelings. Positive values suggest warm feelings.
Why Climate Inputs Matter
Climate comfort is not set by air temperature alone. Radiant surfaces can change body heat loss. Moving air can increase cooling. Humidity changes evaporative loss from skin and breathing. Clothing insulation slows heat transfer. Metabolic rate adds heat from activity. These factors work together. Small changes can shift the final vote.
How This Tool Supports Decisions
This calculator gives PMV, PPD, clothing surface temperature, operative temperature, and heat loss details. It also gives a comfort class. The PPD value estimates the percent of people likely to feel dissatisfied. A low PPD is better. The output helps compare design options before equipment changes are made.
Useful Design Practice
Use measured values where possible. Place sensors near occupants. Check several times of day. Compare sunny, shaded, busy, and quiet periods. Review both PMV and PPD. A PMV between -0.5 and 0.5 is often a practical target. Very low air speed can make warm rooms feel still. High air speed can make cool rooms drafty.
Reading The Result
The result is a model estimate. It does not replace field feedback. People differ by age, adaptation, health, and expectation. Climate, season, and clothing habits also matter. Use this result with surveys and observations. For advanced analysis, run several scenarios. Then compare trends. The best plan usually balances comfort, energy use, and local expectations.
Scenario Testing Tips
Create a base case first. Then change one input at a time. Raise air speed to test fan benefit. Change clothing to test seasonal policy. Change radiant temperature to study windows, roofs, or heated panels. Keep notes for each run. Export the report when a scenario needs review.
Common Mistakes
Avoid mixing units. Enter Celsius values only. Use relative humidity as a percent. Do not enter fan speed as a percentage. Check clothing values carefully. Heavy clothing can strongly change comfort. Always test realistic ranges before final design choices.
FAQs
What does PMV mean?
PMV means Predicted Mean Vote. It predicts the average thermal feeling of a group, from cold to hot, using climate and human activity inputs.
What is a good PMV value?
A PMV near zero is usually best. Many comfort checks use a practical target between -0.5 and 0.5.
What does PPD mean?
PPD means Predicted Percentage Dissatisfied. It estimates how many occupants may feel thermally uncomfortable under the entered conditions.
Why is radiant temperature needed?
Radiant temperature reflects heat exchange with surrounding surfaces. Warm walls, glass, roofs, or equipment can change comfort even when air temperature stays constant.
What is clo in this calculator?
Clo measures clothing insulation. Light summer clothes have lower clo values. Heavy clothing has higher values and reduces body heat loss.
What is met rate?
Met rate describes activity level. Sitting is low. Walking or active work is higher. Higher met values add more body heat.
Can this replace occupant surveys?
No. The result is a model estimate. Use it with real feedback, sensor readings, site checks, and seasonal observations.
Why does air speed affect PMV?
Air movement changes convective heat loss. More air speed often cools occupants, but it can feel drafty in cooler spaces.