Final Program EXPRES 2012 - Conferences

air circulation in the summer, when the temperature ofinter-space should be as low as possible, in principleequal to the outside temperature. Or the openings maybe closed, which is the case during the winter, in orderto trap the air in the inter-space, which will act asinsulation layer, with the temperature above the outsidetemperature, producing lower heat losses of a building(Fig. 1.)Figure 1. Different double-facade constructions: continues(left) and discontinued (right)It is evident that during the heating period, cavitytemperature of a building with a double-façade is abovethe outside one, and will have lower heat losses anddecreased needs for heating. In the summer, during thecooling period, the temperature between the twofacades could be equal or very close to the outsidetemperature, and additionally can have smaller heatgains from solar radiation, depending on glassproperties regarding solar transmittance. As aconsequence, heat gains will not be above the gains ofa single façade buildings. During the summer, oneuses his conscious reactions for the additionalprotection of his body. He may protect himself by hats,or make a shade using a parasol. Similar protection isused in buildings by various curtains, shades, andVenetian blinds on windows, while today copies ofcaps and parasols are constructed, as immovableelements over roofs, or movable, depending on the suntemporary location. All those protections may be alsoused on facades.Examples of building protection from the solarradiation are numerous, especially in the regions oftropical conditions. An illustrative example is abuilding designed by the English architect Grindshawin Seville, built for the EXPO 1992. Movableprotection on the roof is put according to themomentary sun location, controlled by “building’sintelligence” (Fig. 3).VI. BUILDING’S EVAPORATIVE COOLINGFigure 2. The temperatures during the sunny day in JanuaryFigure 2. Shows the course of temperatures in the interspaceon an average sunny day in January, for theSouth-turned double facade, in Belgrade (45NL). Andthe figure 3. the cavity temperature in July summer dayDuring the summer, heat enters into buildings fromthe outside through hot air and solar radiation, but thereare also heat gains inside (lighting, domestic hot watersystems, people, electric appliances and devices). Suchheat must be eliminated so that the inside temperaturewould not be above the planned one, for example 22°C.In conditions when the outside temperature is abovethe human body temperature, the only way for a man toeliminate his inner heat is by perspiration, throughevaporation. A building cannot sweat, so that it has tobe cooled mechanically by air conditioning system.Figure 4. Solar “hats” on the roof of the British pavilion atEXPO 1992.Figure 3. Тhe cavity temperature in July summer day10