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Vytautas Martinaitis
Dept of Heating and Ventilation , Vilnius Gediminas Technical University , Sauletekio al. 11, Vilnius‐40, LT‐10223, Lithuania

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Article
Published: 03 April 2019 in Entropy
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The continuous energy transformation processes in heating, ventilation, and air conditioning systems of buildings are responsible for 36% of global final energy consumption. Tighter thermal insulation requirements for buildings have significantly reduced heat transfer losses. Unfortunately, this has little effect on energy demand for ventilation. On the basis of the First and the Second Law of Thermodynamics, the concepts of entropy and exergy are applied to the analysis of ventilation air handling unit (AHU) with a heat pump, in this paper. This study aims to develop a consistent approach for this purpose, taking into account the variations of reference temperature and temperatures of working fluids. An analytical investigation on entropy generation and exergy analysis are used, when exergy is determined by calculating coenthalpies and evaluating exergy flows and their directions. The results show that each component of the AHU has its individual character of generated entropy, destroyed exergy, and exergy efficiency variation. However, the evaporator of the heat pump and fans have unabated quantities of exergy destruction. The exergy efficiency of AHU decreases from 45–55% to 12–15% when outdoor air temperature is within the range of −30 to +10 °C, respectively. This helps to determine the conditions and components of improving the exergy efficiency of the AHU at variable real-world local climate conditions. The presented methodological approach could be used in the dynamic modelling software and contribute to a wider application of the Second Law of Thermodynamics in practice.

ACS Style

Giedrė Streckienė; Vytautas Martinaitis; Juozas Bielskus. From Entropy Generation to Exergy Efficiency at Varying Reference Environment Temperature: Case Study of an Air Handling Unit. Entropy 2019, 21, 361 .

AMA Style

Giedrė Streckienė, Vytautas Martinaitis, Juozas Bielskus. From Entropy Generation to Exergy Efficiency at Varying Reference Environment Temperature: Case Study of an Air Handling Unit. Entropy. 2019; 21 (4):361.

Chicago/Turabian Style

Giedrė Streckienė; Vytautas Martinaitis; Juozas Bielskus. 2019. "From Entropy Generation to Exergy Efficiency at Varying Reference Environment Temperature: Case Study of an Air Handling Unit." Entropy 21, no. 4: 361.

Preprint
Published: 05 February 2019
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The continuous energy transformation processes in heating, ventilation and air conditioning systems of buildings are responsible for 36% of global final energy consumption. Tighter thermal insulation requirements for buildings have significantly reduced heat transfer losses. Unfortunately, this has little effect on energy demand for ventilation. On the basis of the First and the Second Law of Thermodynamics, the concepts of entropy and exergy are applied to the analysis of ventilation air handling unit (AHU) with a heat pump in this paper. This study aims to develop a consistent approach for this purpose, taking into account the variations of reference temperature and temperatures of working fluids. An analytical investigation on entropy generation and exergy analysis are used, when exergy is determined by calculating coenthalpies and evaluating exergy flows and their directions. The results show that each component of the AHU has its individual character of generated entropy, destroyed exergy and exergy efficiency variation. However, the evaporator of heat pump and fans have unabated quantities of exergy destruction. The exergy efficiency of AHU decreases from 45-55% to 12-15% when outdoor air temperature is within the range of –30°C…+10°C, respectively. This helps to determine conditions and components of improving the exergy efficiency of the AHU at variable real-world local climate conditions. The presented methodological approach could be used in the dynamic modelling software and contribute to a wider application of the Second Law of Thermodynamics in practice.

ACS Style

Giedrė Streckienė; Vytautas Martinaitis; Juozas Bielskus. From Entropy Generation to Exergy Efficiency at Varying Reference Environment Temperature: Case Study of an Air Handling Unit. 2019, 1 .

AMA Style

Giedrė Streckienė, Vytautas Martinaitis, Juozas Bielskus. From Entropy Generation to Exergy Efficiency at Varying Reference Environment Temperature: Case Study of an Air Handling Unit. . 2019; ():1.

Chicago/Turabian Style

Giedrė Streckienė; Vytautas Martinaitis; Juozas Bielskus. 2019. "From Entropy Generation to Exergy Efficiency at Varying Reference Environment Temperature: Case Study of an Air Handling Unit." , no. : 1.

Conference paper
Published: 20 December 2018 in AIP Conference Proceedings
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Drying of solids is one of the most energy-intensive processes in different industries mainly in clay bricks and tiles manufacturing. The construction materials quality closely depends on the drying external and internal parameters and requires a deep analysis of different drying conditions such us air temperature, air humidity and air flow rate in relation with the particular properties of the considered raw material. In order to reduce the consumption of fossil fuels and greenhouse gas emissions in clay tiles manufacturing alternative energies have to be used in this industrial process either as a unique or supplemental source. Thanks to the high thermal conversion efficiency, solar energy is one of the most suitable green energy sources for industrial heat generation. In this paper a small-scale solar drying system of a clay tile sample has been designed under Fez’s climatic conditions. The thermal performance of the considered solar dryer has been evaluated during the least sunny week of the year based on a dynamic simulation environment via TRNSYS software coupled to an external mathematical code estimating the moisture content in the clay tile sample during the drying time. Based on the required air outlet temperature and drying time for clay tile moisture removal process, an optimal configuration of small-scale solar drying system is proposed, with 6 m2 of high pressure evacuated tubes solar collectors, 200 liters of thermal storage tank, 3 m/s of air velocity, 1 kg/s and 0.5 kg/s of water flow, respectively, in solar loop and heat exchanger loop.

ACS Style

M. Bououd; O. Hachchadi; K. Janusevicius; A. Mechaqrane; V. Martinaitis. Energy performance of a clay tiles solar drying system. AIP Conference Proceedings 2018, 2056, 020014 .

AMA Style

M. Bououd, O. Hachchadi, K. Janusevicius, A. Mechaqrane, V. Martinaitis. Energy performance of a clay tiles solar drying system. AIP Conference Proceedings. 2018; 2056 (1):020014.

Chicago/Turabian Style

M. Bououd; O. Hachchadi; K. Janusevicius; A. Mechaqrane; V. Martinaitis. 2018. "Energy performance of a clay tiles solar drying system." AIP Conference Proceedings 2056, no. 1: 020014.

Journal article
Published: 26 July 2018 in Applied Thermal Engineering
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Ventilation and air conditioning systems are emerging as the major energy consumers in low energy buildings. The objective of this paper is to present new methodology for assessment of Air Handling Units (AHUs) taking into account the variations of reference temperature. The methodology using the concept of coenthalpy, developed for heat exchangers and published by the authors previously has been used. Four AHUs that comprise energy transfer devices, such as: Water-to-Air Heater (WAH), Heat Recovery Exchanger (HRE) and Heat Pump (HP) have been investigated. Thermodynamic parameters including Coefficient of Performance (COP), universal and functional exergy efficiencies have been used to compare AHUs and to calculate the exergy destruction in AHU components at variable environment temperature -30°C...+10°C. The results of this study show that using HRE the COP and exergy efficiencies are significantly better compared with AHU without HRE. Using the HRE of higher effectiveness, the thermodynamic indicators can be improved considerably. The study shows that AHUs equipped with HP with advanced control method and HRE are more advantageous compared with other investigated AHUs. The presented methodology could have practical application for evaluating of energy and exergy efficiency of AHUs at different reference temperatures when designing HVAC systems and implementing optimum control methods.

ACS Style

Vytautas Martinaitis; Giedre Streckiene; Audrius Bagdanavicius; Juozas Bielskus. A comparative thermodynamic analysis of air handling units at variable reference temperature. Applied Thermal Engineering 2018, 143, 385 -395.

AMA Style

Vytautas Martinaitis, Giedre Streckiene, Audrius Bagdanavicius, Juozas Bielskus. A comparative thermodynamic analysis of air handling units at variable reference temperature. Applied Thermal Engineering. 2018; 143 ():385-395.

Chicago/Turabian Style

Vytautas Martinaitis; Giedre Streckiene; Audrius Bagdanavicius; Juozas Bielskus. 2018. "A comparative thermodynamic analysis of air handling units at variable reference temperature." Applied Thermal Engineering 143, no. : 385-395.

Conference paper
Published: 16 May 2018 in IOP Conference Series: Materials Science and Engineering
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The building sector is one of the big energy consumers in Morocco, accounting for about 23% of the country's total energy consumption. Regarding the population growth, the modern lifestyle requiring more comfort and the increase of the use rate of electronic devices, the energy consumption will continue to increase in the future. In this context, the introduction of renewable energy systems, along with energy efficiency, is becoming a key factor in reducing the energy bill of buildings. This study focuses on the design and dynamic simulation of an air heating system for the mean categories of the tertiary sector where the area exceeds 750 m3. Heating system has been designed via a dynamic simulation environment (TRNSYS) to estimate the produced temperature and airflow rate by one system consisting of three essential components: vacuum tube solar collector, storage tank and water-to-air finned heat exchanger. The performances estimation of this system allows us to evaluate its capacity to meet the heating requirements in Ifrane city based on the prescriptive approach according to the Moroccan Thermal Regulation. The simulation results show that in order to maintain a comfort temperature of 20°C in a building of 750m3, the places requires a thermal powers of approximately 21 kW, 29 kW and 32 kW, respectively, for hotels, hospitals, administrative and public-school. The heat generation is ensured by a solar collector areas of 5 m², 7 m² and 10 m², respectively, for hotels, hospitals, administrative and public-school spaces, a storage tank of 2 m3 and a finned heat exchanger with 24 tubes. The finned tube bundles have been modelled and integrated into the system design via a Matlab code. The heating temperature is adjusted via two controllers to ensure a constant air temperature of 20°C during the heating periods.

ACS Style

M. Bououd; O. Hachchadi; K. Janusevicius; V. Martinaitis; A. Mechaqrane. Solar air heating system: design and dynamic simulation. IOP Conference Series: Materials Science and Engineering 2018, 353, 012004 .

AMA Style

M. Bououd, O. Hachchadi, K. Janusevicius, V. Martinaitis, A. Mechaqrane. Solar air heating system: design and dynamic simulation. IOP Conference Series: Materials Science and Engineering. 2018; 353 (1):012004.

Chicago/Turabian Style

M. Bououd; O. Hachchadi; K. Janusevicius; V. Martinaitis; A. Mechaqrane. 2018. "Solar air heating system: design and dynamic simulation." IOP Conference Series: Materials Science and Engineering 353, no. 1: 012004.

Journal article
Published: 01 January 2018 in International Journal of Exergy
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ACS Style

Juozas Bielskus; Giedrius Šiupšinskas; Vytautas Martinaitis; Darius Biekša; Giedre Streckiene. Functional exergy efficiency of an air heat recovery exchanger under varying environmental temperature. International Journal of Exergy 2018, 25, 93 .

AMA Style

Juozas Bielskus, Giedrius Šiupšinskas, Vytautas Martinaitis, Darius Biekša, Giedre Streckiene. Functional exergy efficiency of an air heat recovery exchanger under varying environmental temperature. International Journal of Exergy. 2018; 25 (2):93.

Chicago/Turabian Style

Juozas Bielskus; Giedrius Šiupšinskas; Vytautas Martinaitis; Darius Biekša; Giedre Streckiene. 2018. "Functional exergy efficiency of an air heat recovery exchanger under varying environmental temperature." International Journal of Exergy 25, no. 2: 93.

Journal article
Published: 01 January 2018 in International Journal of Exergy
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The ventilation heat recovery exchanger (HRE) for low energy buildings is becoming one of the important heat transformers in the HVAC systems. The purpose of this paper is to develop the possibilities of exergy analysis for the HRE, when the reference temperature (RT) is variable. The method was prepared through consideration of the exergy flow direction changes, when variable RT was placed below, above and across the operating temperature of working fluids. By using the coenthalpy diagrams, there were obtained three functional exergy efficiencies which had greater sensitivity than universal exergy efficiency. The prepared solution allows the reliable using of the ubiquitous thermodynamic (exergy) analysis for energy chain in the HVAC systems. This methodology may be developed for other heat exchangers with different mass flows, operated at near-environmental temperatures. The results could have a practical application for designing the HVAC systems and implementing their exergy optimum operation controls.

ACS Style

Vytautas Martinaitis; Giedrė Streckienė; Darius Biekša; Giedrius Šiupšinskas; Juozas Bielskus. Functional exergy efficiency of an air heat recovery exchanger under varying environmental temperature. International Journal of Exergy 2018, 25, 93 .

AMA Style

Vytautas Martinaitis, Giedrė Streckienė, Darius Biekša, Giedrius Šiupšinskas, Juozas Bielskus. Functional exergy efficiency of an air heat recovery exchanger under varying environmental temperature. International Journal of Exergy. 2018; 25 (2):93.

Chicago/Turabian Style

Vytautas Martinaitis; Giedrė Streckienė; Darius Biekša; Giedrius Šiupšinskas; Juozas Bielskus. 2018. "Functional exergy efficiency of an air heat recovery exchanger under varying environmental temperature." International Journal of Exergy 25, no. 2: 93.

Journal article
Published: 14 March 2017 in Mechanics
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The purpose of this paper is to develop the application of exergy analysis for assessing the performance of building mechanical systems. When exergy analysis is applied to thermal processes in HVAC systems, this method faces the conditions when variable reference temperature is placed below, above and across the operating temperatures of working fluids. Using the derivative status parameter from enthalpy and entropy, the methodology for calculating the exergy efficiency for HVAC equipment is proposed. The capabilities of this method are demonstrated in the case study of exergy analysis of a ventilation heat recovery exchanger. Thermodynamically justified numerical values of the universal and functional exergy efficiencies for variable reference temperatures are shown. The proposed method is distinguished by its universality and can be applied on other HVAC equipment. Results from this study could be useful for creating exergy optimized design and developing efficient control of HVAC systems operating at variable reference temperatures.DOI: http://dx.doi.org/10.5755/j01.mech.23.1.17678

ACS Style

Vytautas Martinaitis; Juozas Bielskus; Karolis Januševičius; Paulius Bareika. Exergy efficiency of a ventilation heat recovery exchanger at a variable reference temperature. Mechanics 2017, 23, 1 .

AMA Style

Vytautas Martinaitis, Juozas Bielskus, Karolis Januševičius, Paulius Bareika. Exergy efficiency of a ventilation heat recovery exchanger at a variable reference temperature. Mechanics. 2017; 23 (1):1.

Chicago/Turabian Style

Vytautas Martinaitis; Juozas Bielskus; Karolis Januševičius; Paulius Bareika. 2017. "Exergy efficiency of a ventilation heat recovery exchanger at a variable reference temperature." Mechanics 23, no. 1: 1.

Conference paper
Published: 01 January 2017 in 2017 THE 2ND INTERNATIONAL CONFERENCE ON ENERGY ENGINEERING AND SMART MATERIALS: ICEESM 2017
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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 seasonal exergy efficiency of any other HVAC equipment.

ACS Style

G. Streckienė; Vytautas Martinaitis; J. Bielskus. Analysis of seasonal exergy efficiency of an air handling unit. 2017 THE 2ND INTERNATIONAL CONFERENCE ON ENERGY ENGINEERING AND SMART MATERIALS: ICEESM 2017 2017, 1 .

AMA Style

G. Streckienė, Vytautas Martinaitis, J. Bielskus. Analysis of seasonal exergy efficiency of an air handling unit. 2017 THE 2ND INTERNATIONAL CONFERENCE ON ENERGY ENGINEERING AND SMART MATERIALS: ICEESM 2017. 2017; ():1.

Chicago/Turabian Style

G. Streckienė; Vytautas Martinaitis; J. Bielskus. 2017. "Analysis of seasonal exergy efficiency of an air handling unit." 2017 THE 2ND INTERNATIONAL CONFERENCE ON ENERGY ENGINEERING AND SMART MATERIALS: ICEESM 2017 , no. : 1.

Journal article
Published: 24 October 2016 in Mokslas - Lietuvos ateitis
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The article presents results of an effective operation analysis of VGTU Environmental Engineering Faculty southern facade integrated unglazed transpired solar collector. During previous research the importance to evaluate influence to ventilation system by such type of collectors was observed. The assessment of analysed collector aerodynamics showed that under specific solar radiation and air flow conditions the amount of energy generated by collector could be smaller than the energy quantity consumed by fans for air suction. The study provides analysis of the coefficient of performance rates and quantities of generated and consumed energy under different operation conditions. The effective operation conditions of collector committed during this research could be useful for designing or creating algorithm for such device. Straipsnyje pristatoma VGTU Aplinkos inžinerijos fakulteto pietiniame fasade integruoto neįstiklinto orinio saulės kolektoriaus efektyvaus veikimo analizė bei jos rezultatai. Ankstesnio tyrimo metu pastebėta, kad, analizuojant tokio tipo kolektorių, svarbu atsižvelgti į jo poveikį vėdinimo sistemai. Įvertinus analizuojamojo kolektoriaus aerodinamines savybes, nustatyta, kad, esant tam tikroms oro srautų ir saulės spinduliuočių vertėms, įrenginio pagamintas energijos kiekis gali būti mažesnis už orui siurbti naudojamų ventiliatorių vartojamą energijos kiekį. Tyrime pateikiama kolektoriaus energijos transformavimo rodiklių bei pagamintų ir suvartotų energijos kiekių kitimo analizė, esant skirtingiems veikimo režimams. Nustatyti kolektoriaus efektyvaus veikimo režimai gali būti naudingi projektuojant ar kuriant tokio tipo įrenginių valdymo algoritmą.

ACS Style

Dovydas Rimdžius; Vytautas Martinaitis; Juozas Bielskus. EFFECTIVE OPERATION INVESTIGATION OF UNGLAZED SOLAR AIR COLLECTOR / NEĮSTIKLINTO ORINIO SAULĖS KOLEKTORIAUS EFEKTYVAUS VEIKIMO TYRIMAS. Mokslas - Lietuvos ateitis 2016, 8, 443 -448.

AMA Style

Dovydas Rimdžius, Vytautas Martinaitis, Juozas Bielskus. EFFECTIVE OPERATION INVESTIGATION OF UNGLAZED SOLAR AIR COLLECTOR / NEĮSTIKLINTO ORINIO SAULĖS KOLEKTORIAUS EFEKTYVAUS VEIKIMO TYRIMAS. Mokslas - Lietuvos ateitis. 2016; 8 (4):443-448.

Chicago/Turabian Style

Dovydas Rimdžius; Vytautas Martinaitis; Juozas Bielskus. 2016. "EFFECTIVE OPERATION INVESTIGATION OF UNGLAZED SOLAR AIR COLLECTOR / NEĮSTIKLINTO ORINIO SAULĖS KOLEKTORIAUS EFEKTYVAUS VEIKIMO TYRIMAS." Mokslas - Lietuvos ateitis 8, no. 4: 443-448.

Journal article
Published: 01 September 2016 in Applied Thermal Engineering
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ACS Style

Vytautas Martinaitis; Giedrė Streckienė; Darius Biekša; Juozas Bielskus. The exergy efficiency assessment of heat recovery exchanger for air handling units, using a state property – Coenthalpy. Applied Thermal Engineering 2016, 108, 388 -397.

AMA Style

Vytautas Martinaitis, Giedrė Streckienė, Darius Biekša, Juozas Bielskus. The exergy efficiency assessment of heat recovery exchanger for air handling units, using a state property – Coenthalpy. Applied Thermal Engineering. 2016; 108 ():388-397.

Chicago/Turabian Style

Vytautas Martinaitis; Giedrė Streckienė; Darius Biekša; Juozas Bielskus. 2016. "The exergy efficiency assessment of heat recovery exchanger for air handling units, using a state property – Coenthalpy." Applied Thermal Engineering 108, no. : 388-397.

Journal article
Published: 01 September 2016 in Energy Procedia
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ACS Style

Karolis Januševičius; Giedrė Streckienė; Juozas Bielskus; Vytautas Martinaitis. Validation of Unglazed Transpired Solar Collector Assisted Air Source Heat Pump Simulation Model. Energy Procedia 2016, 95, 167 -174.

AMA Style

Karolis Januševičius, Giedrė Streckienė, Juozas Bielskus, Vytautas Martinaitis. Validation of Unglazed Transpired Solar Collector Assisted Air Source Heat Pump Simulation Model. Energy Procedia. 2016; 95 ():167-174.

Chicago/Turabian Style

Karolis Januševičius; Giedrė Streckienė; Juozas Bielskus; Vytautas Martinaitis. 2016. "Validation of Unglazed Transpired Solar Collector Assisted Air Source Heat Pump Simulation Model." Energy Procedia 95, no. : 167-174.

Journal article
Published: 01 January 2016 in International Journal of Exergy
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The energy chain of building energy services begins with primary energy resources and ends with building services systems (BSS). The analysis for such chain and its' elements should rely on fundamentals of thermodynamics. This paper pays attention to one of them that exergy efficiency is in the range of 0-1. In this study, exergy analysis of heat recovery exchangers for air handling units is carried out. Special attention is paid to the direction of thermal exergy flow when temperatures inducing heat transfer are close to a near-environmental temperature. On the basis of the proposed methodology, the dependency of exergy efficiency on dimensionless temperature and thermal recuperator efficiency is discussed. It is important to take the dimensionless temperature interval 0-1 into account. Here the exergy efficiency values are the lowest. Design and management measures should be used to avoid operating a heat exchanger there.

ACS Style

Vytautas Martinaitis; Giedrė Streckienė. Concerning exergy efficiency evaluation of heat recovery exchangers for air handling units. International Journal of Exergy 2016, 20, 381 .

AMA Style

Vytautas Martinaitis, Giedrė Streckienė. Concerning exergy efficiency evaluation of heat recovery exchangers for air handling units. International Journal of Exergy. 2016; 20 (3):381.

Chicago/Turabian Style

Vytautas Martinaitis; Giedrė Streckienė. 2016. "Concerning exergy efficiency evaluation of heat recovery exchangers for air handling units." International Journal of Exergy 20, no. 3: 381.

Journal article
Published: 01 August 2015 in Energy and Buildings
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ACS Style

Vytautas Martinaitis; Edmundas Kazimieras Zavadskas; Violeta Motuziene; Tatjana Vilutienė. Importance of occupancy information when simulating energy demand of energy efficient house: A case study. Energy and Buildings 2015, 101, 64 -75.

AMA Style

Vytautas Martinaitis, Edmundas Kazimieras Zavadskas, Violeta Motuziene, Tatjana Vilutienė. Importance of occupancy information when simulating energy demand of energy efficient house: A case study. Energy and Buildings. 2015; 101 ():64-75.

Chicago/Turabian Style

Vytautas Martinaitis; Edmundas Kazimieras Zavadskas; Violeta Motuziene; Tatjana Vilutienė. 2015. "Importance of occupancy information when simulating energy demand of energy efficient house: A case study." Energy and Buildings 101, no. : 64-75.

Journal article
Published: 24 November 2014 in JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT
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Modern 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 issues of the RE hybrid energy transformation systems’ modelling and about the efficient use of resources to ensure the same level of energy services.

ACS Style

Vygantas Žėkas; Vytautas Martinaitis; Giedrė Streckienė; Tatjana Vilutienė. A QUANTITATIVE EVALUATION OF THEORETICAL RENEWABLE ENERGY POTENTIAL OF THE BUILDING SITE. JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 2014, 20, 873 -883.

AMA Style

Vygantas Žėkas, Vytautas Martinaitis, Giedrė Streckienė, Tatjana Vilutienė. A QUANTITATIVE EVALUATION OF THEORETICAL RENEWABLE ENERGY POTENTIAL OF THE BUILDING SITE. JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT. 2014; 20 (6):873-883.

Chicago/Turabian Style

Vygantas Žėkas; Vytautas Martinaitis; Giedrė Streckienė; Tatjana Vilutienė. 2014. "A QUANTITATIVE EVALUATION OF THEORETICAL RENEWABLE ENERGY POTENTIAL OF THE BUILDING SITE." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 20, no. 6: 873-883.

Research article
Published: 13 November 2014 in Building Services Engineering Research and Technology
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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.

ACS Style

V Martinaitis; D Biekša; A Rogoža; R Savickas. Quantitative estimation of improvements in the efficiency of district heating substation control system. Building Services Engineering Research and Technology 2014, 36, 455 -468.

AMA Style

V Martinaitis, D Biekša, A Rogoža, R Savickas. Quantitative estimation of improvements in the efficiency of district heating substation control system. Building Services Engineering Research and Technology. 2014; 36 (4):455-468.

Chicago/Turabian Style

V Martinaitis; D Biekša; A Rogoža; R Savickas. 2014. "Quantitative estimation of improvements in the efficiency of district heating substation control system." Building Services Engineering Research and Technology 36, no. 4: 455-468.

Journal article
Published: 01 June 2014 in Energy and Buildings
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ACS Style

Rūta Mikučionienė; Vytautas Martinaitis; Eugenijus Keras. Evaluation of energy efficiency measures sustainability by decision tree method. Energy and Buildings 2014, 76, 64 -71.

AMA Style

Rūta Mikučionienė, Vytautas Martinaitis, Eugenijus Keras. Evaluation of energy efficiency measures sustainability by decision tree method. Energy and Buildings. 2014; 76 ():64-71.

Chicago/Turabian Style

Rūta Mikučionienė; Vytautas Martinaitis; Eugenijus Keras. 2014. "Evaluation of energy efficiency measures sustainability by decision tree method." Energy and Buildings 76, no. : 64-71.

Conference paper
Published: 30 May 2014 in Springer Proceedings in Physics
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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.

ACS Style

Vygantas Žėkas; Vytautas Martinaitis; Giedrius Šiupšinskas. Data File of the Building Site’s Renewable Energy Characteristics. Springer Proceedings in Physics 2014, 405 -410.

AMA Style

Vygantas Žėkas, Vytautas Martinaitis, Giedrius Šiupšinskas. Data File of the Building Site’s Renewable Energy Characteristics. Springer Proceedings in Physics. 2014; ():405-410.

Chicago/Turabian Style

Vygantas Žėkas; Vytautas Martinaitis; Giedrius Šiupšinskas. 2014. "Data File of the Building Site’s Renewable Energy Characteristics." Springer Proceedings in Physics , no. : 405-410.

Conference paper
Published: 01 January 2014 in The 9th International Conference "Environmental Engineering 2014"
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ACS Style

Karolis Januљevicius; Juozas Bielskus; Vytautas Martinaitis. Thermodynamic simulation of solar thermal system. The 9th International Conference "Environmental Engineering 2014" 2014, 1 .

AMA Style

Karolis Januљevicius, Juozas Bielskus, Vytautas Martinaitis. Thermodynamic simulation of solar thermal system. The 9th International Conference "Environmental Engineering 2014". 2014; ():1.

Chicago/Turabian Style

Karolis Januљevicius; Juozas Bielskus; Vytautas Martinaitis. 2014. "Thermodynamic simulation of solar thermal system." The 9th International Conference "Environmental Engineering 2014" , no. : 1.

Journal article
Published: 25 November 2013 in Mokslas - Lietuvos ateitis
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The article presents simulation based exergy analysis used for comparing solar thermal systems applied for preparing domestic hot water. The simulation of flat and vacuum tube solar collector systems was performed in TRNSYS simulation environment. A period of one year under Lithuanian climate conditions was chosen. Simulation was performed on 6 min time step resolution by calculating energy and exergy flows and creating balance calculation. Assessment results at system and element levels have been presented as monthly variation in efficiency. The conducted analysis has revealed that the systems designed to cover equal heat energy demand operates in different exergetic efficiencies. Article in Lithuanian. Santrauka Straipsnyje eksergijos požiūriu nagrinėjamos dvi saulės kolektorių sistemos, skirtos karštam vandeniui gaminti. Plokščiųjų ir vakuuminių saulės kolektorių modeliavimas atliktas TRNSYS programa. Modeliuota vienerių metų periodui Lietuvos klimatinėmis sąlygomis 6 minučių laiko žingsniu skaičiuojant energijos ir eksergijos srautus kiekvienam laiko žingsniui ir sudarant energinius ir ekserginius balansus. Sistemos ir posistemių efektyvumo rodiklių kitimo rezultatai pateikti grafiškai. Išanalizavus akivaizdu, kad pasirinktomis sąlygomis plokščiųjų ir vakuuminių saulės kolektorių sistemos, turinčios tą pačią funkcinę paskirtį, veikia skirtingu efektyvumu.

ACS Style

Juozas Bielskus; Karolis Januševičius; Vytautas Martinaitis. A COMPARISON OF THE THERMODYNAMIC EFFICIENCY OF VACUUM TUBE AND FLAT PLATE SOLAR COLLECTOR SYSTEMS / VAKUUMINIŲ IR PLOKŠČIŲJŲ SAULĖS KOLEKTORIŲ SISTEMŲ EKSERGINIŲ EFEKTYVUMŲ PALYGINIMAS. Mokslas - Lietuvos ateitis 2013, 5, 404 -409.

AMA Style

Juozas Bielskus, Karolis Januševičius, Vytautas Martinaitis. A COMPARISON OF THE THERMODYNAMIC EFFICIENCY OF VACUUM TUBE AND FLAT PLATE SOLAR COLLECTOR SYSTEMS / VAKUUMINIŲ IR PLOKŠČIŲJŲ SAULĖS KOLEKTORIŲ SISTEMŲ EKSERGINIŲ EFEKTYVUMŲ PALYGINIMAS. Mokslas - Lietuvos ateitis. 2013; 5 (4):404-409.

Chicago/Turabian Style

Juozas Bielskus; Karolis Januševičius; Vytautas Martinaitis. 2013. "A COMPARISON OF THE THERMODYNAMIC EFFICIENCY OF VACUUM TUBE AND FLAT PLATE SOLAR COLLECTOR SYSTEMS / VAKUUMINIŲ IR PLOKŠČIŲJŲ SAULĖS KOLEKTORIŲ SISTEMŲ EKSERGINIŲ EFEKTYVUMŲ PALYGINIMAS." Mokslas - Lietuvos ateitis 5, no. 4: 404-409.