Planing a new build-up area should take into consideration the increase of temperature in cities and energy consumption. Basic principles of ecologically oriented urbanism include respecting climate factor of territory by correctly designed construction. Based on comparsion of heat inertia of various areas of city it is apparent that more intensively build-up areas are cooled much more slowly than surrounding landscape. This is affected mainly by large heat inertia of buildings materials, less green areas and slow movement of air due to dense and high buildings. Water constitutes a potential for improvement of micro-climate. Through drops of aerosol and natural evaporation they increase air humidity and decrease its temperature. Ecologically oriented urbanism should take in part micro climate and future energy demand.