The Outdoor Comfort tab shows an overview of the perceived environmental condition based on the UTCI model.
The Universal Thermal Climate Index (UTCI), introduced in 1994, aims to be the measure of human physiological reaction to the atmospheric environment.
It considers:
dry bulb temperature
mean radiant temperature
wind speed
relative humidity
to calculate a reference environmental temperature causing strain when compared to an individual's response to the real environment. It is based on Fiala et al.'s multi-node model of thermo-regulation.
The UTCI equivalent temperature is a function of the above parameters, which are combined in a multinode thermo-physiological model that takes into account clothing insulation and metabolic rate. From this aUniversal Thermal Climate Index (UTCI) of perceived thermal stress is derived.
Clima allows the user to visualize the annual UTCI equivalent temperature as heatmap under various environmental conditions.
The UTCI temperature can be converted in a scale assessing thermal stress, displayed by Clima in a heatmap graph.
Learn more about the Outdoor Comfort tab by watching the following video.
The UTCI tab allows users to analyze outdoor thermal comfort for a combination of different meteorological conditions based on the presence or absence of sun and wind.
Clima leverages the several models implemented in Pythermalcomfort.
The "Solar gain on people" calculates the solar gain to the human body, so the mean radiant temperature. To simulate a sunless situation, Clima considers the person surrounded by surfaces that shade him, all of which tend toward dry bulb temperature;
Wind data is obtained directly from the weather file. The windless situation sets the value at 0.5 m/s, which is the minimum value allowed by the UTCI model.
The UTCI can then be visualized for the entire year for the scenario chosen.
The values are then converted into a scale assessing thermal stress, either because of cold or heat. Therefore, a second chart maps if people will experience thermal stress for all the hours of the year for corresponding UTCI temperatures.
The UTCI is a useful tool to design the outdoor space, to maximize the number of comfortable hours. The designer can influence two factors out of the four driving outdoor comfort: radiant temperature (i.e. exposure to the sun) and wind speed (i.e. exposure to the wind).
