Particularities of determining primary energy needs for building materials/Pirminės energijos poreikių statybinėms medžiagoms nustatymo ypatumai

Civil buildings in Lithuania consume one half of final energy or about 70% of heat generated in thermoelectric and heat power stations. However, energy is necessary not only for exploitation but also for the creation of buildings: manufacture of building materials, transportation and construction. For global energy saving in the construction industry, at the state level, it is important to determine an optimum ratio between energy requirement for building creation and exploitation. Taking into account the durability of buildings for the evaluation of strategic relation ships between energetics and construction industry it is reasonable to use a physical building life cycle energy requirement model, because the reliability of an economical prognosis is usually lower than that in physical processes. In this work generalised ratios are suggested for energy requirement by the main building materials, which can be used in the calculation of a physical building life cycle model. In collecting this information three sources were used, namely: from Lithuania, former USSR and Western countries. In the beginning we hoped that the collected information would show higher energy needs for the production of building materials in Lithuania and other former USSR countries than those in developed countries, where manufacturing technology is more modern, and energy saving measures have been implemented earlier. After collecting more data, it was evident from foreign—literature that in Western countries the energy needs are bigger because they are based on other energy needs estimation levels. In the estimation data of energy needs for the Lithuanian building materials industry the levels of technological processes are not clearly described. In this case an application of such data for a physical model of life cycle cost estimations cannot be used directly. For a more detailed analysis 10 building materials were chosen: silicate brick, ceramic brick, rockwool, polyctirol, cement, timber, steel, glass, concrete, ferro-concrete. Energy requirements are classified according to 4 levels of full technological processes, i.e.: for the main process, for raw materials, for machines and for machines that produce these machines. Taking into account the indetermination of the information of data sources, the values can be recommended only for a tentative evaluation. More precise values can be obtained by a detailed analysis of the Lithuanian industry. For building construction industry prognosis one monitoring for building and insulation material manufacturing processes is necessary taking into account different technological levels and processes. First Published Online: 26 Jul 201

Šilumos siurblių integravimo į oro ruoštuvus energinė analizė / Energy efficiency gain of heat pump integration in air handling units

This article describes how heat pumps (HP) integrated in air handling units (AHU) proud against the analogous AHU with external heat pumps. Two almost identical (except heat pump position) air handling units were analysed. During the experimental study supply and return air temperatures and AHU’s fans power were measured. Efficiency indicators and consumed energy were calculated based on measured data. Seasonal performance factor (SCOP) and total annual energy use was evaluated for both units. During the economical evaluation was found, that AHU with integrated HP can payback within 10 years compared with AHU combined with external heat pump. Santrauka Straipsnyje nagrinėjama, kiek šilumos siurbliai, integruoti į oro ruoštuvus, yra pranašesni už analogiškus išorinius šilumos siurblius. Nagrinėjami du realiomis sąlygomis veikiantys analogiški oro ruoštuvai – vienas su integruotu, o kitas su išoriniu šilumos siurbliu. Tyrimo metu išmatuotos šių įrenginių rodiklių vertės, lemiančios jų energinį naudingumą, tokios kaip oro temperatūra ir vartojama energija. Tam, kad galima būtų nustatyti sezoninį įrenginių efektyvumą (SCOP), šie rodikliai pagal LST EN14825:2016 buvo matuojami esant skirtingai aplinkos temperatūrai. Nustatyti išvestiniai efektyvumo rodikliai bei, remiantis standartu, apskaičiuotas abiejų įrenginių šilumos siurblių efektyvumas. Lyginant pradinių investicijų ir šildymo sezono energijos kaštų skirtumus, įvertintas oro ruoštuvų su integruotais šilumos siurbliais ekonominis naudingumas. Reikšminiai žodžiai: oro ruoštuvas, integruotas šilumos siurblys, vėdinimas, šilumogrąža, energinis efektyvumas, realios sąlygos.

The analysis of balancing water cooling systems and making management decisions regarding office buildings

The paper analyses a cooling system installed using 268 fan coils and having an area of 7900 m2 in a public building situated in Vilnius city. A comparison between a constant flow system having three way valves, a variable flow system having manually balanced valves and a variable flow system having automatically balanced control valves is made. The analysis has been performed to find out initial investments, installation costs and operating costs during 10 year period. Calculation has showed advantages of the variable flow. The overall cost of the system having manually balanced and two way control valves is 20% lower than that of the constant flow system. The overall cost of the system having automatically balanced control valves is 37% lower than that of the constant flow system. The marked differences may increase in case of growth in electricity price. Article in Lithuanian. Biurų pastato vandeninės vėsinimo sistemos balansavimo ir valdymo sprendimų analizė Santrauka. Nagrinėjami trys labiausiai paplitę administracinių pastatų vandeninės vėsinimo sistemų balansavimo ir valdymo sprendimai: pastovaus srauto sistema, kintamo srauto sistema su rankiniais balansavimo ventiliais ir kintamo srauto sistema su automatiniais balansavimo ir valdymo vožtuvais. Atliekami vieno konkretaus pastato detalūs skaičiavimai: lyginamos sistemų pradinės investicijos, montavimo ir eksploatacijos išlaidos. Gauti rezultatai rodo, kad dažniausiai naudojama ir paprastai projektuojama pastovaus srauto sistema su triangiais vožtuvais yra prasčiausia pagal visus kriterijus. Energijos tausojimo prasme išsiskiria sistema su automatiniais vožtuvais. Susumavus eksploatacijos išlaidas per 10 metų ir pradines investicijas, gauta, kad pastovaus srauto sistema yra brangiausia. Kintamojo srauto sistema su rankiniais balansavimo ventiliais yra 20 % pigesnė, o su automatiniais – net 37 %. Reikšminiai žodžiai: vėsinimas, hidraulinis balansavimas, efektyvumas, energijos taupymas, aprišimo schemos, srautas

The analysis of applying different coolants for cooling systems in the office building

The paper analyzes air conditioning systems of different coolants on the basis of an example of a typical office building. Depending on the type of a coolant fan coil unit, active chilled beams, variable refrigerant volumes and air cooling systems were designed. The article suggests hydraulic and aerodynamic calculations and evaluates initial investments, energy expenditures and operating costs of the compared systems. Considering economic calculations, the pay-back time of the systems was assessed and the sensitivity analysis of electricity prices was carried out. The results of the conducted investigation show the most appropriate analysed system for office buildings taking into account the efficient use of electricity and initial investments. Article in Lithuanian. Skirtingų šilumnešių vėsinimo sistemų taikymo biurų pastate analizė Santrauka. Tipinio administracinio pastato pavyzdžiu nagrinėjamos skirtingų šilumnešių vėsinimo sistemos. Atsižvelgiant į šilumnešio tipą suprojektuotos ventiliatorinių konvektorių, aktyviųjų šalčio sijų, freoninė ir orinė vėsinimo sistemos. Atlikti hidrauliniai ir aerodinaminiai skaičiavimai, įvertintos sistemų pradinės investicijos, apskaičiuotos energijos sąnaudos ir eksploatacijos išlaidos. Ekonominio skaičiavimo metu buvo įvertintas sistemų atsipirkimo laikas ir atlikta elektros kainų jautrumo analizė. Šio tyrimo rezultatai rodo, kokia sistema yra tinkama biurų pastatams pagal efektyvų elektros energijos naudojimą ir pradines investicijas. Raktiniai žodžiai: vėsinimas, šilumnešiai, ventiliatoriniai konvektoriai, orinė sistema, freoninė sistema, aktyviųjų šalčio sijų vėsinimo sistema

Feasibility study of heat recovery form treated wastewater in wastewater treatment plant and use it in nearby object

Nowadays, the supply of energy from renewable energy sources is important in the energy sector of every country, so it is necessary to pay attention to alternative sources with thermal potential. The aim of this article is to perform an analysis of the possibilities of using heat from the wastewater treated at the Vilnius wastewater treatment plant. The work determines the temperature and flow fluctuations of the wastewater treated in the treatment plant, the theoretical heat potential. The heat demand of a commercial building is calculated. Based on these data, the parameters of a heat pump using treated wastewater are determined and a system model is created in a energy simulation software and the heat supply of the building is estimated. Article in Lithuanian. Išvalytų nuotekų šilumos atgavimo nuotekų valykloje ir panaudojimo gretimame objekte galimybių analizė Santrauka Straipsnyje analizuojamos šilumos atgavimo iš Vilniaus nuotekų valykloje išvalytų nuotekų bei jos panaudojimo netoliese esančio stambaus objekto šilumos poreikiams tenkinti galimybės. Darbe nustatomi valykloje išvalytų nuotekų temperatūros ir debito svyravimai ir teorinis atliekinės šilumos potencialas. Apskaičiuojami prekybos paskirties pastato šilumos poreikiai. Remiantis šiais duomenimis nustatomi šilumos siurblio, naudojančio išvalytas nuotekas, šiluminiai parametrai ir sudaromas sistemos skaitmeninis modelis kompiuterinėje programoje bei įvertinamas pastato aprūpinimas šiluma. Reikšminiai žodžiai: atsinaujinantys energijos ištekliai, nuotekų valykla, šilumos siurblys, šilumos energija, prekybos pas­kirties pastatas, EnergyPRO

Selection of the climate parameters for a building envelopes and indoor climate systems design / Klimato parametrų, skirtų pastatų atitvarų ir mikroklimato sistemoms projektuoti, parinkimas

The current research considers the principles of selection of the climate information needed for the building envelope and indoor climate design and adopted in Russia and some European countries. Special reference has been made to the shortcoming of methodologies that include the notion of a typical year, and the advantages of climate data sets generated via software-based designs, using pseudo-random number generators. The results of the average temperature of the coldest five-day period with various supplies were calculated using the numerical Monte-Carlo simulations, as well as the current climate data. It has been shown that there is a fundamental overlap between the statistical distribution of temperatures of both instances and the possibility of implementation a probabilistic-statistical method principle in the development of certain climate data, relative to envelopes and thermal conditions of a building. The calculated values were combined with the analytic expression of the normal law of random distribution and the correlations needed for the main parameter selection. Santrauka Straipsnyje nagrinėjami informacijos apie išorės sąlygas atrankos principai, reikalingi pastato patalpų mikroklimatui sukurti remiantis Europos šalių (ir Rusijos) patirtimi. Dėmesys atkreiptinas į metodikų trūkumą, kuriose vartojama „tipinių metų“ sąvoka, ir į klimato duomenų rinkinių, įtrauktų į programinę įrangą, privalumus. Vidutinė šalčiausių penkių dienų temperatūra buvo apskaičiuota taikant skaitmeninius Monte Carlo modelius ir dabartinius klimato duomenis. Buvo įrodyta, kad abiem atvejais temperatūros statistinis pasiskirstymas iš esmės sutampa ir yra tinkamas pastatų atitvaroms ir mikroklimato sistemoms projektuoti. Apskaičiuotos vertės buvo įvertintos atsitiktinio pasiskirstymo metodo analitine raiška ir pagrindiniam parametrų pasirinkimui reikalingomis koreliacijomis. Reikšminiai žodžiai: pastatas; atitvaros; šildymo sistema; mikroklimatas; projektinės vertės.

Experimental study on energy efficiency of a small adsorption cooling device producing up to 8 kW / Adsorbcinio iki 8 kW vėsos galios įrenginio eksperimentinis efektyvumo tyrimas

The analysis of scientific literature shows that the actual efficiency of the adsorption cooling device has not been properly examined. This article presents experimental study on energy efficiency of the adsorption cooling device (max capacity 8 kW) produced at the Laboratory of Building Energy and Microclimate Systems of Vilnius Gediminas Technical University. The study has focused on the measurement of the actual temperatures and flow rate of a heating source, chilled water, a supply of cooled water to the chiller, electricity consumption for circulation pumps and chiller fans. The article presents collected statistical data and shows the dependency of chilled water and heat source temperatures evaluating the coefficients of performance (COP) and electrical efficiency (EER). The received results show higher electrical efficiency of the examined device than that of a conventional compressor system. Santrauka Mokslinės literatūros analizė parodė, kad realiai veikiančių įrenginių faktinis efektyvumas nėra gerai žinomas, ypač įrengus šaltojo klimato zonos šalyse. Todėl šiame darbe atliekamas eksperimentinis VGTU Pastato energetinių ir mikroklimato sistemų laboratorijoje (PEMS) įrengto SORTECH AG gamintojo ACS 08 adsorbcinio (maksimali vėsinimo galia – 8 kW) įrenginio efektyvumo tyrimas. Matuojamos faktinės šilumnešio, atšaldomo vandens, tiekiamo į aušyklę, aušinimo skysčio temperatūros su debitais bei aušyklės ir cirkuliacinių siurblių elektros sąnaudos. Atliekama sukauptų duomenų statistinė analizė ir pateikiama atšaldomo vandens bei šilumnešio temperatūrų priklausomybė, vertinant energijos transformavimo COP bei elektrinį (EER) tiriamojo įrenginio koeficientus. Tyrimo rezultatai rodo didesnį nei tradicinės kompresorinės sistemos tiriamojo įrenginio elektrinį efektyvumą. Reikšminiai žodžiai: atsinaujinantieji ištekliai; adsorbcinis vėsinimo įrenginys; energijos transformavimo koeficientas (COP)

Minimizacija stroškov življenjskega cikla rotacijskih prenosnikov toplote za stavbne prezračevalne sisteme v hladnih podnebjih

This article presents an analysis of rotary heat exchangers (RHE) used as heat recovery units in building ventilation systems in cold climates. Usually, heat exchangers with the highest heat transfer efficiency are the preferable option for this purpose. However, such exchangers usually have the highest media pressure drop, thus requiring the highest amount of energy for media transportation. In this study, the problem is solved by analysing the lifecycle cost (LCC) of the RHE including both the recovered heat and the electricity consumed in the fans of the air handling unit (AHU). The purpose of the investigation was to determine the optimal set of geometrical characteristics such as the exchanger%s length, foil thickness, the height and width of the air channel. Two hundred and seventy different combinations were examined using analytical dependencies and ANSYS simulations. The results are compared with experimental data obtained earlier at the KOMFOVENT laboratory. The results show that the best overall energy efficiency is obtained in heat exchangers that do not offer the best heat recovery efficiency, and LCC differences in the same climatic and economic conditions can go as high as 31 %, mainly due to the geometrical parameters of the heat exchanger

A Review of the Life Cycle Analysis Results for Different Energy Conversion Technologies

Technologies that use renewable energy sources (RES) are crucial to achieving decarbonization goals, but a significant number of studies show their relatively high environmental impact during the production phase. Therefore, technologies need to be compared in terms of their life-cycle environmental impact. The life cycle analysis (LCA) methodology is well known and widely employed. However, problems related to the methodological choices prevent taking full advantage of the LCA, as the results of numerous studies are often incomparable. The presented review aims to critically compare the impact of different energy generation technologies—RES (as well as non-RES) energy generators and co-generators. The numeric results are structured and analyzed in terms of the global warming potential (GWP) and non-RES primary energy consumption. The results show that RES technologies are superior compared to conventional fossil-fuel-based systems in most cases, and the high impact during the production and installation phases is compensated in the operational phase. The high variations in GWP from similar technologies result from different methodological choices, but they also show that the wrong choice of the technology in a certain location might cause serious environmental drawbacks when the impact of the RES technology exceeds the impact of fossil fuel-based technologies. Cogeneration technologies using waste as a fuel may even have a negative GWP impact, thus showing even higher potential for decarbonization than RES technologies