PLEROMA DESIGN STUDIOS | Predicted Heat Strain Model (PHS)

Inputs

Air temperature

°C

Mean radiant temperature

°C

Air speed

m/s

≈ 0.4 km/h

🎛️ Ceiling Fan Wall Switch: Speed 0: Still Air (0.1 m/s / 0.4 km/h)

OFF 1 2 3 4 5

Relative humidity

Metabolic rate

met

Clothing level

clo

Create custom ensemble

Outdoor air temperature (6 am) °C

SI/IP

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Documentation 🖨️ Print Report

Predicted Heat Strain (ISO 7933)

Analytical Evaluation of Thermal Stress, Physiological Core Temperature & Water Loss

✔ PHYSIOLOGICALLY ACCEPTABLE

CORE TEMP (Tre)

37.1 °C

< 38.0°C Safe Limit

TOTAL WATER LOSS

420 g

Sweat Secretion

DURATION LIMIT (Dlim)

> 480 min

Full Shift Allowable

⏱️

Core Temperature Speedometer Dial

36.5°C — 39.0°C

PHYSIOLOGY STATUS Normothermic (Safe)

CORE TEMP 37.1 °C

👤

Physiological Strain Avatar

Thermal Balance

🙂

Safe Homeostasis

Core temperature well within ISO 7933 threshold

Air Temp 34.0 °C

Sweat Rate 350 g/h

Max Allowable Loss 1,500 g

Core Limit Temp 38.0 °C

⚠️

Maximum Allowable Exposure Duration (Dlim)

ISO 7933 Safety Horizon

> 480 min

Critical (< 30 min) Cautious (30 - 120 min) Full Shift (> 480 min)

📈

Predicted Heat Strain Simulation Curves

Temporal Dynamics

Maximum allowable exposure time within which the physiological strain is acceptable (no physical damage is to be expected) calculated as a function of:

max rectal temperature = min

water loss of 5% of the body mass for 95% of the population = min

water loss of 7.5% of the body mass for an average person = min

NOTE: The PHS model (ISO 7933) allows the analytical evaluation of the thermal stress experienced by a subject in a hot environment. The PHS can only be used for dry-bulb temperatures between 15 and 50°C, air speeds between 0 and 3 m/s, metabolic rates between 1.7 and 6.8 met, total clothing insulation between 0.1 and 1.0 clo, and when the difference between the mean radiant temperature and the air temperature is between 0 and 60°C.