1. Gerd Jendritzky, Germany
The Universal Thermal Climate Index UTCI COST Action 730
Gerd Jendritzky, Germany
George Havenith, U.K.
Philipp Weihs, Austria
Ekaterina Batchvarova, Bulgaria

2. Why UTCI?
Assessment of the thermal environment: Key issue in human biometeorology
History: >100 simple thermal indices
Last 35 years: Heat budget modelling
Integration of new knowledge and concerns
Need: Harmonization  UTCI (ISB, WMO)
COST Action (Example: UV-Index)

3. George Havenith, 2003

4. M + W + Q* + QH + QL + QSW + QRe + S = 0
The human heat budget
M + W + Q* + QH + QL + QSW + QRe + S = 0
M Metabolic rate
W Mechanical power
Q* Radiation budget (Tmrt,v)
QH Turbulent flux of sensible heat (Ta,v)
QL Turbulent flux of latent heat (diffusion water vapour) (e,v)
QSW Turbulent flux of latent heat (sweat evaporation) (e,v)
QRe Respiratory heat flux (sensible and latent) (Ta,e)
S Storage

5. Problem: Insufficiency of available assessment procedures
Problem: Insufficiency of available assessment procedures. Thus strong need to make use of the progress in science and modelling in thermophysiology of the last years. Strategy: Bundling of interdisciplinary expertise in a COST Action 730 in close cooperation with ISB Commission 6 on UTCI. Experts from 18 countries plus WMO in three working groups : WG1 Thermophysiological modelling and testing WG2 Meteorological and environmental data WG3 Applications.

6. Thermophysiological Assessment of the Thermal Environment
Descriptive term
Thermophysiology
Meteorology
PMV
PT* °C
PET °C
OUT_SET* °C
AT 1,2,3 °C
(WCT) °C
Tsk °C
SR kgs-1
ESK Wm-2
Wsk %
Icl clo
etc. A s e m n t
WG1 Ta
Tmrt v e
Heat budget
models

7. Action 730 on UTCI
Fiala et al. 2001

8. Simulated whole body and local thermophysiological variables
Mean skin temperature, Tsk,m
Head core temperature (hypothalamus), Thy
Total evaporative heat loss from the skin, Esk
Skin wettedness, wsk
Local skin temperatures of face and hands, Tsk,f,h
Cooling time for Tsk,f,h < 0°C
Assessment problem!

9. Thermophysiological Assessment of the Thermal Environment
Descriptive term
Thermophysiology
Meteorology
WG2
PMV
PT* °C
PET °C
OUT_SET* °C
AT 1,2,3 °C
(WCT) °C
Tsk °C
SR kgs-1
ESK Wm-2
Wsk %
Icl clo
etc. A s e m n t Ta
Tmrt v e
Heat budget
models

10. Tmrt Uniform temperature of a black body enclodure that results in the same radiant heat exchange as under actual conditions
Direct solar radiation
Diffuse solar radiation
Reflected solar radiation
Infrared radiation from the sky
Infrared radiation from the surroundings

11. Projected Surface Area

12. WG 3 Applications Public weather service Public health system
Precautionary planning
Climate impact research

13. Selected subproplems Heat budget modelling WG1
Assessment of physiological variables WG1
Acclimatisation WG1
Meteorological input, in particular radiation  Tmrt WG2
Definition of areas of validity, requirements WG2
Applications (Needs of users) WG3

14. Summary: Basic features of UTCI
Thermophysiologically significant in the whole
range of heat exchange conditions
Valid in all climates, seasons and scales
Steady-state conditions: Applicability
Independent of individual characteristics
Prediction of whole body and local thermal
effects
Based on the most advanced multi-node models
Temperature scale index
International standard
for human biometeorological core applications