2007, Piran, Slovenia

Universal Thermal Climate Index
imaginary black enclosure in which an occupant would exchange the same amount of radiant
heat as in the actual non-uniform space (ASHRAE, 2004), was also derived. Because direct
measures of radiation fluxes were not available in this study, Tmrt was assessed by using the
RayMan program (Matzarakis et al., 2007). Air temperature, relative humidity, wind speed
and Tmrt were used as input parameters to calculate the thermal index PMV which provide
the mean vote of the majority of people in terms of a 7-point thermal sensation rating scale,
going from neutral to hot/cold thermal sensations. Subjective characteristics were considered
with reference to a standard person (sex: man; age: 35 years old; height: 1.75 m; weight: 75
kg; position: standing; activity: 80 W). An automatic procedure, able to process previous data,
allowed the calculation of PMV starting from a prefixed clo value of 0.1 (Start clo). The clo
unit is a measure of clothing insulation (1 clo = 0.155 m 2 K/Watt). The procedure ran
recursively with a progressive increasing from the “Start clo” (0.2 clo, 0.3 and so on) and it
stopped when the value of PMV was included in the thermal neutrality range. The latter clo
value represents the assessment of the minimum clothing insulation value required to
maintain the thermal neutrality (min_clo) (Fig. 1). This value is similar to the determination
of the neutral required clothing insulation (IREQneutral) (ISO 11079, 1999).
Figure 1: The procedure to assess the minimum value of clothing insulation needed for to
reach the thermal neutrality (min_clo). Legend: PMV is the Predicted Mean Vote.
Trends of min_clo were assessed for the three Italian cities on an hourly basis for each season
(Winter: Dec-Jan-Feb; Spring: Mar-Apr-May; Summer: Jun-Jul-Aug; Autumn: Sep-Oct-
Nov). A statistical parametric method of linear correlation analyses was applied. The Pearson
correlation coefficient (r) was calculated and the statistical significance (P) was tested by
using the Student t-test.
Operational biometeorological procedure
Weather forecast data of air temperature (°C), relative humidity (%), wind speed (ms-1), longwave
and short-wave radiation (W.m -2 ), direct solar radiation (W.m -2 ) were obtained for 72
hours by using the local area modelling WRF-NMM (Nonhydrostatic Mesoscale Model –
Weather Research and Forecasting). The current configuration depends on global forecast
model NCEP-GFS with four daily runs (00 UTC, 06 UTC, 12 UTC, 18 UTC) and 0.5° of
horizontal resolution. Every simulation furnishes a complete meteorological parameterization,
centred over Italy, on a horizontal grid of 140 x 279 point with 34 vertical levels. The
estimation of the Tmrt for outdoor environments was carried out by a formula, which took
into consideration long- and short-wave radiations and the direct solar radiation. In this study
weather forecast data and the estimation of Tmrt were processed using the procedure
described in Fig. 1 with 0.1° of horizontal resolution, corresponding to 10 km at our latitudes.
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