Vytautas Martinaitis

Criterion to evaluate the "twofold benefit" of the renovation of buildings and their elements

Abstract At present a benefit of energy saving projects for buildings renovation is considered as only the saving of energy. It is obvious, however, that most energy saving measures allow one not only to save energy, but also to improve the building’s condition and in turn to increase the value of a building. In practice, considering only the reduction of energy cost, the implementation of such measures is usually hard to prove through cost effectiveness. The authors of this paper suggest one of possible methods of how the assessment of the cost effectiveness of energy saving measures could include a twofold benefit of building’s renovation—the energy saving and the rehabilitation of the buildings elements physical condition. The presented method could form a “new attitude” towards the assessment of the energy saving projects for buildings renovation.

Energy Efficiency Challenges in Multi-Apartment Building Renovation in Lithuania

Abstract The paper presents a position of the authors on the current setup of the multi-apartment renovation process in Lithuania. The conducted investigation includes the actual case study analysis of the group of residential buildings in Birstonas. The paper deals with three areas that have a major impact on the success of the overall renovation process. The areas include the currently applied mechanisms for identifying and evaluating energy efficiency measures, data analysis of measuring actual energy efficiency and determination of the economic feasibility of the renovation process. Research results clearly indicate that the current shape of the program scheme is far from completion. The paper produces recommendations and research findings that could be used for further improvement on the process.

Analytic calculation of degree-days for the regulated heating season

This paper describes a method for the degree-days calculation by means of the proposed cumulative air temperature duration function for the heating season by additionally setting the temperature which determines the limits of the heating season in this function. The results of calculations received under the Lithuanian climate conditions have been compared with the factual data. The results of degree-days per month calculations received without setting the limit temperatures into the function have been compared with the calculation methods of other researchers. The method proved to be acceptable and useful solving energy consumption problems in relation to of the building life cycle.

CORRECTION OF A DESIGNED BUILDING'S HEAT BALANCE ACCORDING TO ITS REAL HEAT CONSUMPTION

Abstract One of the most important issues in the implementation of energy saving measures is a proper evaluation of possible energy savings. If energy savings are overestimated in an energy audit (EA), a situation may occur where after the renovation, the implemented energy saving measures is not paid back or their pay back time is longer than expected before the funds (mostly loaned) were invested. To avoid such a situation, the procedure of a buildings energy audit should involve the correction of calculated heat balance according to its real heat consumption, recalculated to the nonnative conditions. In manipulating different building parameters of not exact meanings, it is necessary to attain that the buildings heat demand before renovation (theoretically calculated by the same methodology and parameters as demand after renovation) would be as close as possible to the actual heat consumption, recalculated under normative conditions. Only after such a fitting of the actual and theoretical heat demand...

A quantitative evaluation of theoretical renewable energy potential of the building site

AbstractModern building design process is becoming more complex. Local conditions and future constructions are computer-simulated. The aim of this simulation is to evaluate theoretical RE potential for the successful and efficient exploitation of the new building. As usual, in the simulation process of local conditions, the assessment of the renewable energy potential is one of the key elements. This article presents and analyses the idea of the quantitative evaluation of renewable energy (RE) theoretical potential of the building site and the approach on how to prepare initial data file for further process of site energy development concept creation. The study describes a building site that is undergoing the RE evaluation in terms of thermodynamic and descriptive statistics characteristics. The applicability of the offered approach was verified in the case study. The specified evaluation of the combined energy fluctuation throughout the year provides new and potentially crucial information about the issu...

Quantitative estimation of improvements in the efficiency of district heating substation control system

Evaluation of energy performance of buildings is becoming increasingly applicable and constantly requires more and more precise forecasting of energy savings, which could be further interpreted in the economic evaluations of building renovation. Despite the development of a wide range of energy auditing methodologies and software tools, one important component has still not garnered enough attention and has no quantitative evaluation method. This component is energy savings attributed to improved performance of the heating control system. Currently, these savings are evaluated on the basis of arbitrary indices that have been extrapolated from real modernization projects. This approach is simplification and usually has no actual energy savings estimations. This article presents a method for the evaluation of energy savings attributed to improved performance of the district heating substation control system. The idea is based on employing the specific heat losses (H) of a building. Theoretically, the evaluated H values represent ideal work performance of the heating control system and the actual collected data represent the current state of efficiency of the control system. The estimation of possible energy saving potential between ideal and actual H values results in quantitative energy savings due to the improved performance of the heating control system. This article presents in detail the method application sequence. It provides additional explanation on actual data processing mechanisms by applying regression analysis in order to determine base temperature and accumulated duration curves. Practical application : None of the energy audit methodologies or software tools answer the question on the amount of energy that can be saved due to improved performance of the heating control system. The method presented in this article is simple, saves on time and enables energy auditors to have a quantifiably based groundwork for estimation of possible energy savings attributed to improved performance of the heating control system.

Data File of the Building Site’s Renewable Energy Characteristics

After choosing the engineering solution of Integrated whole Building Design Process (IWBDP) and Global Optimized Local Designed (G.O.L.D) one of the most important elements of the creative process becomes the input data. There is a lack of comprehensive approach to the locally disposed building site’s RE and higher overall exploitation of this potential. That is why there is a need to have a prepared data file presenting building site’s energy potential. The aim of the described work is to create the input data file, to present the file creation process and the key characteristics. Building site data must be handy not only for the initial conception creation stage, but also for the subsequent operating and maintenance of the building on going through the BIM systems. Data must be based on the long-term observations and target research of the building site. Data file is required to provide information about the standard nature processes occurring in the defined geometric boundaries of the site. The results of the work are the proposed forms of input data file, structure and main energy characteristics of the building site. When planning the development of the building site, creating the design concept, and selecting the combination of RE integration technologies, data array proposed in the article will allow a more objective selection of the optimal solution of RE integration.

EXPRESSING THE BUILDING ENERGY SYSTEMS THERMODYNAMIC SEASONAL EFFICIENCY

In order to reduce impact to environment, a qualitative approach of energy saving is global aspect that is included in various forms of CO 2 emissions, primary energy limitations and benchmarks in EU and member countries policy. Exergy analysis allows expressing the quality of energy flows in comparison to ambient or other reference conditions. Despite of this valuable information, this concept is not widely used in engineering practice. The article suggests the calculation procedure for sessional or periodical thermodynamic (exergy) efficiency in relation to variable reference conditions. Knowledge about defined procedures unlocks the possibility to fill up the implementation gap for building system engineering practice where seasonal performance parameters are widely used to express efficiency. Prepared algorithm allows determining seasonal or periodic thermodynamic efficiency of individual elements and energy transfer chains in building energy systems. Defined calculation procedure workflow is suitable for integrated approach when coupled heat transfer and fluid flow processes are explored in short time steps with dynamic simulation software tools. Presented algorithm ensures result that fits in thermodynamically correct range 0-1 and helps to summarize separate time step results. By adding duration of specific conditions, this analysis enables to identify critical peak periods and base load conditions across operation period. The presented framework fills the gap in lack of systematic expression for seasonal thermodynamic efficiency and suggests the process for calculation procedures workflow. DOI: https://doi.org/10.3846/enviro.2017.271

Analysis of seasonal exergy efficiency of an air handling unit

Ventilation systems play an important role for providing suitable indoor climate in buildings. Improving these systems allows promoting energy efficiency in building sector, which is responsible for a large percentage of global energy consumption. Therefore, this work focuses on assessment of ventilation air handling unit (AHU) using thermodynamics. The exergy analysis is used to evaluate the performance of an AHU. Special attention is made about seasonally varying exergy flows of a system. As efficiency of a ventilation system is closely linked to local climate, especially to the varying reference temperature. The paper presents an approach for calculating the seasonal exergy efficiency and gives the results of the AHU analysis. The case study reveals that the highest exergy consumption is when the outdoor temperature is −2.5 °C. The AHU case with heat recovery and water heater is the most efficient comparing to other cases investigated. The use of this methodology may be extended for determining of the ...