After having developed a general outdoor climate analysis, it’s necessary to understand how it affect the microclimate by urban and the design of a building; in the previous assignment particular attention was on the dry bulb temperature, as the most common index to describe a climate. However, other important parameters that have to be considered are:
-       the relative humidity, which describes the portion of vapour in relation to saturation: hotter air can contain more vapour than colder and when cooled to the limit (dew point) the surplus condenses;
-       the wind, which is affected by topography, vegetation, closeness to the sea and surrounding buildings;
-       the precipitation, considering both rain and snow;
-       solar radiation, which depends on the latitude, the altitude, the time of the year and seasoning;
-       sky conditions, since energy is also dissipated from the earth to the sky by long-wave heat radiation, depending on air and sky conditions, such as cloudiness and pollution. The sky vault acts as a cold, black body: a heat sink, which may receive a considerable amount of heat during clear nights, but also during the day. An equivalent sky temperature can be defined for the sky vault, sometimes as low as 25 K below the air temperature;
-       other phenomena, such as hail, frost, thunder, fog, smog, dust and sandstorms, hurricanes and earthquakes.
The thermal equilibrium of human beings, who exchange heat through conduction, convection, radiation and evaporation/condensation, must be maintained within narrow limits for survival and even narrower range of comfort, which is a subjective experience. To handle comfort, it is necessary to define some kind of index, or a ‘comfort zone’ where the majority of people experience well-being; for this purpose, a number of scales were developed. In particular, Gagge’s DISC index expresses degrees of discomfort rather than comfort; according to this, the most common definition of the comfort zone is DISC ±0,5, which means that 80% of the population is satisfied.
Considering the Standard Effective Temperature (SET), a DISC of ±0.5, the clothing varying from 0.6 clo (light summer clothing) to 1.0 clo (normal clothing), the level of activity varying from 1 met (sedentary activities, such as sleeping or sitting) to 2.0-4.0 met (house cleanings) and the air movement varying from 0.1 m/s (still indoor air) to 0.5 m/s (using fans), it’s possible to develop a comfort diagram.