Government Regulation 361/2007 Coll. classifies work into eight metabolic classes and sets a maximum permissible operative or globe temperature for each. Since the NV 330/2023 Coll. amendment took effect on 2024-01-01, exceeding that value for classes IIb to V triggers a mandatory work-alternation and safety-break regime whose duration is computed by the ČSN EN ISO 7933 heat-balance (Predicted Heat Strain) method — the static exposure-time tables of Annex 1 Part B were repealed outright.
No standalone formula is published for this standard; see programmable logic and parameters below.
Governing metric: Average operative temperature to (indoor) or globe temperature tg (outdoor), against the Annex 1 Part A Table 2 maximum for the metabolic work class
| Parameter | Value |
|---|---|
classBandsWm2 | {"I":[0,80],"IIa":[81,105],"IIb":[106,130],"IIIa":[131,160],"IIIb":[161,200],"IVa":[201,250],"IVb":[251,300],"V":[301,null]} |
table2MaxOperativeTempC | {"I":27,"IIa":26,"IIb":30,"IIIa":30,"IIIb":26,"IVa":24,"IVb":20,"V":20} |
table2ClothingClo | 0.5 |
operativeEqualsGlobeMaxAirVelocityMS | 0.2 |
standardBodySurfaceM2 | 1.8 |
longTermFluidLossLimitGm2 | 2160 |
longTermFluidLossLimitLitres | 3.9 |
shortTermHeatStorageLimitKJm2 | 180 |
shortTermCoreTempRiseC | 0.8 |
acclimatizationWeeks | 3 |
unacclimatizedLongTermReductionPercent | 30 |
exceptionallyHotDayOutdoorMaxC | 30 |
nonAirConditionedClassIandIIaCeilingC | 34 |
fluidLossHygienicLimitLitresPer8h | 1.25 |
protectiveDrinkMinReplacementPercent | 70 |
amendmentEffectiveDate | "2024-01-01" |
Five things this engine deliberately does not do. (1) It does not present the class IIb/IIIa 30°C figure as an exposure ceiling. Table 2 footnote 3 requires the short-term and long-term energy-expenditure limits to be met AT THE SAME TIME as the microclimate values, so for classes IIb-V the 30°C cell is a screening trigger into the § 4(1) regime; showing it as 'heavy work allowed to 30°C' would be a genuine safety misstatement even though the cell is correctly transcribed. This is the highest-risk mis-presentation for this standard. (2) It does not reconstruct the repealed Annex 1 Part B exposure-duration tables 1a-2c, and it does not encode the 36°C trigger deleted from § 4(1) — both were removed with effect from 2024-01-01, and pre-2024 KHS PDFs and secondary summaries still carry them. (3) It emits no stop-work: § 4(1) obliges work alternation and safety breaks, and the only stop-work-shaped provision in the microclimate chapter is on the cold side (§ 7(5), −30°C). (4) It does not treat the 30°C exceptionally-hot-day threshold as a protective trigger: it RELAXES the class I/IIa Table 2 limit, and the only duty it creates is mandatory fluid replacement. (5) It does not branch the heat calculation on sex. Table 2 footnotes 1-2 (class IVb not whole-shift permissible for women; class V not permissible for women and not whole-shift for men) are physical-load limits from a different chapter and are surfaced as a note only. Also not blended in: Annex 1 Part C (deep mines, a separate dry-bulb regime with its own 45 tables under § 5(4)), Table 3's air-conditioned setpoints and Table 4's vertical gradient, which are design and comfort requirements rather than exposure limits. WBGT is not used anywhere in the Czech heat provisions and this engine is not routed through the calculator's WBGT input. The decree's acclimatization test is calendar (at least 3 weeks at the assessed workplace) while the calculator's input is physiological; the mapping is documented rather than presented as equivalence. Operative temperature is defined as a time-weighted average over effective working time, so an instantaneous reading screens a shift-average limit and is not a compliance determination.
Programmable logic: Metabolic rate in watts is divided by the regulation's standard 1.8 m² body surface to give gross W/m², then mapped to the Table 1 classes: I ≤80, IIa 81-105, IIb 106-130, IIIa 131-160, IIIb 161-200, IVa 201-250, IVb 251-300, V ≥301 W/m². Table 2 maxima, defined at 0.5 clo: I 27°C, IIa 26°C, IIb 30°C, IIIa 30°C, IIIb 26°C, IVa 24°C, IVb 20°C, V 20°C. The metric is average operative temperature indoors per § 3b(1), or globe temperature outdoors per § 3b(5) where air movement and humidity are expressly excluded; globe temperature may stand in for operative temperature only where air velocity is at or below 0.2 m/s, and air temperature is never a substitute. For classes IIb to V an exceedance engages § 4(1)'s work-alternation and safety-break regime, bounded by the long-term and short-term permissible work durations that § 4(2) requires to be computed under ISO 7933 with the Czech D_lim criteria: long-term load capped at 2160 g/m² of fluid loss (3.9 L per eight-hour shift) and short-term load at 180 kJ/m² of accumulated heat, which the decree equates to a 0.8°C core-temperature rise, for acclimatized and unacclimatized alike. § 4(3) then cuts the LONG-TERM duration by 30% for an unacclimatized class IIb-V employee, leaving the short-term criterion untouched because the decree states it is identical for both states. Where the ISO 7933 inputs are missing the engine returns requiresPHSCalculation rather than producing minutes. For classes I and IIa there is no § 4(1) schedule duty at all: an exceedance is a control duty, and on an exceptionally hot day — maximum outdoor air temperature above 30°C — the Table 2 value is waived entirely at a § 3a(g) workplace, subject to the Table 5 ceiling of 34°C at non-air-conditioned class I and IIa workplaces and to mandatory fluid replacement.
Required inputs: metabolicRateW
Optional inputs: operativeTempC, globeTempC, airTempC, meanRadiantTempC, relativeHumidity, windSpeedMS, clothingInsulationClo, acclimatization, maxTempC, outdoor