The installation of an energy-saving facility must be preceded by analysisof its financial effectiveness. Among methods enabling such evaluation is thebasic net profit calculation method. For this, the annual consumption of electricityfor ventilation or of thermal energy for heating must be determined. The calculationformula uses the sum of energies for temperatures within the range fromthe calculation temperature for the area in question to the long-term average ofthe maximum temperature at the site, or to the temperature at which the heatingpower is zero. It is necessary to know the summary time of occurrence of a giventemperature during a year. The site data can only be assessed based on long-termmeteorological information. In fact, data used by current national standards todescribe climatic conditions in the Czech Republic are from the years 1901 to1950.The dependence of the average yearly temperature on altitude is shown inFig. 1 for the 1961 1990 and 1991 2000 periods. It is evident that the averagetemperatures for the latter period are nearly 0.6 K higher than those for the formerperiod, irrespective of the altitude.In this paper the climatic conditions are assessed based on daily datameasured throughout the period from 1 January 1991 to 31 December 2000.Weather stations were ...
