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The high share of global energy costs to create an indoor climate has been of increasing interest to the global community for several decades and is increasingly the focus of policy. This paper analyses the energy performance gap between actual energy consumption and energy demand obtained during the dynamic energy simulation and building certification. To identify the energy performance gap, an existing office of energy efficiency class B was selected as a case study. The simulation program IDA Indoor Climate and Energy was used to create a dynamic energy model, based on the designed documentation and the actual indoor climate parameters recorded by the building management system. The results of the case study showed that the accuracy and reliability of the results presented by the dynamic energy model of the building directly depend on the assumptions. The correct values of the internal heat gains, indoor climate parameters, human behavior, air quality levels at different times of the day and season, HVAC system operation parameters and operation modes, specific fan powers of ventilation systems, the seasonal energy efficiency of cooling equipment and characteristics of sun protection measures have to be selected. [ABSTRACT FROM AUTHOR]

With the growth of energy-efficient building sector, ventilation systems are becoming increasingly important not only of fresh air supply but also in terms of energy consumption. The aim of this paper is to describe and analyse the operation of an air handling unit (AHU) with a heat pump using energy and exergy analyses under the variable environmental temperature (from –30 °C to 10 °C). The application of selected methods is illustrated in a case study of an AHU using environmental temperatures of Vilnius city during heating season (from the beginning of October to the end of April). An analytical method for determining distribution of the environmental (outdoor air) temperature is used. Energy and exergy analyses showed periods when the highest amounts of energy and exergy were consumed and the greatest exergy losses occurred. This allowed to reveal the component of the system with the highest exergy losses – the heat pump evaporator. Therefore, further research is needed for its design and application. At the end of the article, the seasonal indicators of the AHU with heat pump operation were calculated: coefficient of performance and exergy efficiency. The presented research procedure could be applied to the analysis of other energy systems and processes in them. [ABSTRACT FROM AUTHOR]

Inefficient heat use in old multi-fiat residential buildings causes problems to the residents spending a large part of their incomes on heat bills as well as for the State working towards achieving goals of energy efficiency increase, climate change mitigation and energy security. However, the Lithuanian program of multifiat building renovation keeps stalling, and therefore danger that much of this energy saving potential will go unrealised appears. The paper is concerned with the problems that arise when renovating multi-fiat buildings according to the existing legislation. In this case, the emphasis is placed on the factors that have influence on decisions made by building owners to either participate or not in the renovation program. The paper demonstrates that the currently employed method of evaluating building renovation projects does not correctly reflect the benefits of refurbishment and gives financially unattractive financial indicators. Thus, the new method of investment distribution is introduced considering three aspects of benefits for building renovation. The case analysed demonstrates how the suggested "ternary benefit" method could be used for differentiating between financing sources and presenting relevant information to the building owners. Another related problem is heat saving assessment in the building refurbishment process. The paper argues that energy audits are far more suitable for the evaluation of modernisation projects than for energy performance certification. [ABSTRACT FROM AUTHOR]

Evaluation of robotic energetics while moving on rough terrain becomes a difficult task without having the information about the movement on even terrain. The problem appears in selection of gaits depending on how much power robot consumes. In this paper, energy consumption of a hexapod walking robot dependence on different gaits and speed is observed. Three most common gaits were used in this experiment: tripod gait, bipod gait and wave gait. Results clearly show that while moving at slow speed, the least energy is consumed by wave gait. As the speed increases, bipod gait selection is required to lower energy consumption. Finally, tripod gait must be selected at even higher speed. [ABSTRACT FROM AUTHOR]

The renovation of old buildings is essential for the efficient use of energy. Improvement in the thermal characteristics of the building envelope makes a significant effect on energy savings. For assessing the real impact on buildings, energy efficiency of various measures applied in renovation is one of the most important problems. Actual energy savings significantly differ from those calculated according to the methodology described in technical documents. The article analyses 8 renovated buildings. Three main external elements, including walls, windows and roofs, in all buildings were retrofitted. Using theoretical energy savings through each element and knowing the actual savings of the building, actual energy savings through each element are found. Theoretical energy savings for heating after renovation, in every case, are bigger than actual energy consumption for heating before renovation. There is a big difference between theoretical and actual savings after renovation, sometimes up to 2 times. The paper describes dependency between the envelope area of buildings and the mismatch factor of theoretical and actual consumption. The payback period of renovated buildings is calculated using theoretical and actual data. The theoretical payback period of renovation is up to 2 times shorter than the actual one. The calculation method for the estimation of the actual payback period using the mismatch factor has been proposed, and the model of the building has been made to calculate its probable payback period. [ABSTRACT FROM AUTHOR]

The article analyzes changes in energy demand for a greenhouse. The worked out solution to the construction of the building is a partially glazed greenhouse having a glazed roof and open vertical barriers. Design Builder software has been applied for analytical calculations and greenhouse modelling as well as for introducing changes in annual energy demand and establishing temperature variations and regime. The paper reviews the obtained results and diagrams, performs analysis and draws conclusions. [ABSTRACT FROM AUTHOR]

The paper explains the results of a detailed energy audit of the buildings of Vilnius Gediminas Technical University. Energy audits were performed with reference to the international scientitle project. The article presents the methodology and results of detailed measurements of energy balance characteristics. [ABSTRACT FROM AUTHOR]

The paper presents a model for selection of building's external elements. Were analyzed 6 variations of walls and windows area ratio. The authors determined the criteria of those alternatives, which are as follows: heat losses through the building external walls, heat losses through the building windows, heat losses through the bearer thermal bridges, heat losses above the rated air infiltration, external heat inflows in the building from the outside, the building's energy consumption without consideration of heating system performance, and walls and windows price ratio. According to available data, the initial matrix of a problem was determined. By the use of multiple assessment methods, such as SAW (Simple Additive Weight) COPRAS (Complex Proportion Assessment) and MEW (Multiplicative Exponential Weighting) were calculated the optimal variant of a window and wall aria variation. [ABSTRACT FROM AUTHOR]

The paper presents the current situation with the renewable energy sources in Lithuania. An overview of legislation promoting the production and usage of renewable energy in Lithuania is presented. Renewable energy production methods suitable for Lithuanian conditions, their advantages and disadvantages are discussed. It is shown that there is no any promotion from the state for usage of solar energy in private households. The potential of solar energy usage is determined. In order to show the effectiveness of solar thermal energy utilization under similar climatic conditions presented the example of promotion policy model and its results in Poland. [ABSTRACT FROM AUTHOR]