Residential buildings in Latvia are one of the essential heat consumers during the heating season. The majority of Latvian as well as European residential buildings were constructed within the period from 1965 to 1990. Introduction presents brief overview of current situation in Latvian and EU countries. This chapter provides overview of real energy consumption and definition of buildings technical conditions. Materials and methods are based on evaluation of standardized energy consumption in two kindergartens and multi apartment buildings including also dynamic energy simulation. Chapter on thermal performance of building envelope provides an extensive comparison of heat transfer coefficients in non-renovated buildings as well as comparison with normative values. Section on energy consumption of existing multi apartment buildings presents review of buildings real energy consumption before and after renovation. In addition this chapter evaluated indoor air quality. This study was done in order to define necessary reconstruction goals to reach European Regional Development Fund project "A New Concept for Sustainable and Nearly Zero-Energy Buildings" Nr. 1.1.1.1/16/A/007 main targets. Аннотация. Жилые здания в Латвии являются одним из основных потребителей тепла в отопительный сезон. Большинство латвийских и европейских жилых зданий были построены в период с 1965 по 1990 год. Введение представляет краткий обзор текущей ситуации в Латвии и странах ЕС. В этой главе представлен обзор реального потребления энергии и определение технических условий для зданий. Материалы и методы основаны на оценке стандартизированного потребления энергии в двух детских садах и многоквартирных домах, включая также динамическое моделирование энергии. В главе, касающейся тепловых характеристик ограждающих конструкций зданий, дано подробное сравнение коэффициентов теплоотдачи в не отреставрированных зданиях и сравнение их с нормативными значениями. В разделе об энергопотреблении существующих многоквартирных домов представлен обзор реального потребления энергии зданиями до и после модернизации. Кроме того, в этой главе дается оценка качества воздуха в помещении.

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The calculation of thin-walled rods is extremely relevant problem of structural mechanics and not only from the scientific standpoint, but also due to the widespread use of so-called lightweight thin-walled steel structures for construction engineering sector. Regardless of a sufficiently large number of studies connected with the statics of thin-walled rods, the dynamics of such systems have not been thoroughly studied yet. Based on one of the forward-looking theories of calculation i.e. the semi-shear theory by Slicker, the paper provides a technique for solving the dynamics problems of thin-walled rods. The stiffness and mass matrices of the finite element system are obtained for linear approximation of the form functions, and the natural vibration frequencies of the rods are calculated. The obtained solution is accomplished by the extrapolation method of estimating the accuracy of numerical methods for solving mathematical problems.

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