Table 2.

Uncertainty budget.

Uncertainty Source	Uncertainty Cause	Symbol	Type	Distribution	Measurement Conditions
					Indoor (After Subject Acclimatisation)		Outdoor (Without Subject Acclimatisation)
					Expanded Uncertainty	Standard Uncertainty	Expanded Uncertainty	Standard Uncertainty
Measurand	Individual and Spatial	$u_{m,ind}$	A	Normal	0.20 °C	0.10 °C	0.20 °C	0.10 °C
	Temporal	$u_{m,temp}$	A	Rectangular	0.25 °C	0.09 °C	0.50 °C	0.18 °C
	Environmental	$u_{m, env}$	B	Rectangular	0.25 °C	0.09 °C	0.50 °C	0.18 °C
Instrument	Calibration	$u_{i,cal}$	B	Normal	0.15 °C	0.08 °C	0.15 °C	0.08 °C
	Drift	$u_{i,drift}$	B	Normal	0.10 °C	0.05 °C	0.10 °C	0.05 °C
	Temperature resolution	$u_{i,res}$	A	Normal	0.10 °C	0.05 °C	0.10 °C	0.05 °C
	Response time	$u_{i,time}$	A/B	Normal	negligible	-	negligible	-
Environmental Influence quantities	Temperature effect 1	$u_{e,temp}$	B	Rectangular	0.10 °C	0.04 °C	0.20 °C	0.07 °C
	Skin emissivity 2	$u_{e,emi}$	B	Rectangular	0.05 °C	0.02 °C	0.10 °C	0.04 °C
	Mean radiant temperature 3	$u_{e,mrt}$	B	Rectangular	0.05 °C	0.02 °C	0.20 °C	0.07 °C
Operator	Target uniformity	$u_{o,target}$	B	Rectangular	0.05 °C	0.02 °C	0.05 °C	0.02 °C
	Angle incidence	$u_{o,angle}$	A/B	Normal	negligible	-	negligible	-
Composed Uncertainty		fixed threshold			0.40 °C	0.20 °C	0.62 °C	0.31 °C
		statistical threshold			0.28 °C	0.14 °C	0.42 °C	0.21 °C

¹ Evaluated on the basis of a device temperature between 20 ± 2 °C (20 ± 5 °C) for indoor (outdoor) conditions. ² Evaluated on the basis of a skin emissivity between 0.980 ± 0.003 (0.980 ± 0.006) for indoor (outdoor). ³ Evaluated on the basis of a mean radiant temperature between 20 ± 2 °C (20 ± 10 °C) for indoor (outdoor) conditions.