Protect workers by calculating WBGT for sun, shade, or indoor tasks today. Review workload limits, hydration reminders, and color-coded warnings before shifts start daily.
These sample readings show typical field scenarios.
| Scenario | Environment | Tnwb (°C) | Tg (°C) | Tdb (°C) | WBGT (°C) |
|---|---|---|---|---|---|
| Morning concrete pour | Outdoor sun | 24.0 | 36.0 | 30.0 | 26.4 |
| Midday rebar tying | Outdoor sun | 27.0 | 44.0 | 35.0 | 30.0 |
| Indoor finishing | Indoor/shade | 25.5 | 33.0 | — | 27.8 |
Wet Bulb Globe Temperature (WBGT) combines humidity effects, radiant heat, and air temperature into one index for heat stress planning.
Tnwb = natural wet bulb temperature, Tg = globe temperature, Tdb = dry bulb (air) temperature.
WBGT is best used with a heat illness prevention program. Combine engineering controls, scheduling, hydration access, and worker monitoring to reduce risk.
Use WBGT results to plan breaks and hydration smartly.
Construction work combines metabolic heat, radiant exposure, and limited airflow. WBGT converts these stressors into a single planning number so supervisors can adjust schedules, crew size, and controls before productivity and safety drop.
WBGT uses natural wet bulb (Tnwb), globe temperature (Tg), and sometimes air temperature (Tdb). On many sites, Tnwb commonly tracks the mid‑20s °C during humid periods, while Tg can rise above 40 °C near sunlit concrete, steel, or equipment.
Place sensors at worker height, near the task area, and away from artificial shade unless workers are shaded too. For crane decks, roofing, or rebar mats, readings can differ sharply from nearby shaded trailers. Record the location and time with each set.
Use the outdoor equation when solar load is present: 0.7×Tnwb + 0.2×Tg + 0.1×Tdb. Use the indoor/shade equation when solar load is removed: 0.7×Tnwb + 0.3×Tg. This avoids underestimating radiant heat impacts.
Clothing and PPE can add heat burden by reducing evaporation and trapping heat. Light, breathable workwear may be near 0 °C adjustment, while heavier protective layers can add several °C. This calculator applies an additive adjustment (°C WBGT) to support conservative planning.
Metabolic heat rises quickly with task intensity. “Moderate” work such as steady walking, rebar tying, or formwork often tolerates higher WBGT than heavy shoveling or concrete finishing. As WBGT approaches your threshold, increase recovery time, rotate crews, and reduce peak effort.
Hydration supports sweating, but water alone may not replace salts during prolonged sweating. Use frequent small drinks, provide shaded recovery, and watch for cramps, unusual fatigue, headache, dizziness, or confusion. Empower workers to stop and report symptoms immediately.
Daily WBGT logs help justify schedule changes, track seasonal patterns, and support incident investigations. Export CSV for spreadsheets or PDF for toolbox talks. Pair records with notes on wind, humidity, cloud cover, and clothing to compare similar tasks across different conditions.
For daily operations, take readings at least hourly during rising heat, and whenever crews move between shade and sun. Combine WBGT guidance with task planning, shaded staging, cooled break areas, and active supervision. A consistent process reduces heat illness risk and limits production disruptions caused by preventable medical events.
WBGT is a heat stress index used to plan work, rest breaks, hydration, and controls. It combines humidity, radiant heat, and air temperature to better reflect worker strain than temperature alone.
Only for outdoor conditions with sun exposure. Indoor or shaded conditions use a formula based on Tnwb and Tg, so Tdb is optional for that case.
Tg reflects radiant heat from sun and hot surfaces. It can rise sharply on steel, concrete, and equipment, which is why WBGT can be high even when shade temperatures seem moderate.
Use 0 °C for light, breathable clothing. Add a positive adjustment when PPE reduces ventilation or evaporation, such as coveralls or impermeable layers. Choose conservative values when uncertain.
Not as calculation inputs. WBGT readings already reflect humidity and airflow through the wet bulb and globe sensors. The optional notes fields help document site conditions for reporting and comparisons.
No. It supports planning and communication. Always follow your company’s heat illness prevention program and applicable regulations, and consult your safety lead for site-specific thresholds.
If adjusted WBGT is very high for the task, stop or greatly reduce heavy work, move crews to cooling, and monitor symptoms. Escalate immediately for confusion, fainting, or suspected heat stroke.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.