The paper presents an analysis of several variants of energy-efficient solutions for hot water supply systems in Minsk buildings that ensure significant reduction of energy for hot water supply in comparison with the existing level. The different systems have been considered as technical facilities for usage of solar energy and secondary heat sources and which are based on heat recovery of “grey” waste water, solar collector, photoelectric transducer, heat pump. Comparative analysis of the considered variants shows economic efficiency of waste water heat utilizers. An advantage of such system is in its all-year round usage in comparison with a solar collector. The second variant that is a combination of waste water heat utilizer and a solar collector that increases energy saving but it requires the increase of capital expenses. The third variant completely covers expenses of heat energy which is necessary for hot water supply. It is neces-sary to attract attention to the fact that expenses in the first two variants are close to the required ones but values of the third variant may significantly exceed the reliable level. The paper contains analytical material of Belarusian and Vietnamese researchers who were actively involved in implementation of the joint Belarusian-Vietnamese project “Usage of Renewable Power Sources in Physical-Mathematical Model of Heat Regime of Energy-Efficient House” (Project code: VAST. HTQT. Belarus. 03/2012–2013).

The paper presents dependences required for calculation of heat and energy for building operation within the period of its functioning and mean specific power of heat loss.

The variant of efficient combination of two renewable energy sources as a biogas system and a water heating solar system has been considered for power supply of individual dwellings. Criteria dependence has been suggested for determination of solar system power efficiency. Its legitimacy has been proved by an experiment. Power efficient solar system has been proposed with peculiar features of its designing and due account of energy flow distribution in technology of biogas production.

The paper contains an approximate evaluation of solar and wind energy potential in Vietnam. Possible energy generation using non-conventional energy sources is cited for a number of regions in Vietnam.

The paper gives an analysis of power system in Vietnam. Data on power resources of the country and forecasts pertaining to production and consumption (oil, gas and solid fuel) up to 2020 are cited in the paper.