• Energy Research

Abstract The economic considerations force the building body optimization during its design, as well as during the modernization of existing facilities. The thermal modernization effects are calculated according to the national rules and standards. The theoretical savings from the reduction of heat losses by transmission and ventilation in a secondary school located in Poland were calculated (59–71%) and compared with the real savings (33%), calculated on the base of data from the measurements conducted in several heating seasons before and after modernization. The achieved ecological effect (33%) was also lower that theoretical one (69%). The results of this work are worth taking into account in further schools modernizations and a city planning. The simple model for energy use estimation was proposed. The bigger sample of schools will be analyzed to propose changes in the calculation procedure after the end of the whole study.

In this work, a new plasma reactor operating with a butane/propane (C4H10/C3H8) gaseous mixture, designed for hydrogen molecule production, was experimentally studied. This reactor is based on a rotating electrode, biased by an AC high voltage. The plasma discharge was investigated for different AC voltages, rotational frequencies, and gas flow rates. A discharge in the filamentary mode was produced as proved by the electrical characterization. Gas Chromatography (GC) was applied to study the LPG remediation. The maximum conversion factors of 70% and 60% were found for the C3H8 and C4H10, respectively, with an H2 selectivity of 98%. Hydrogen atomic lines from the Balmer series and various molecular bands were detected by optical emission spectroscopy (OES). The stark broadening of the Hα Balmer line was used for the determination of the electron density. The spectra simulation of the C2 band was permitted to obtain the gas temperature while the first five lines of hydrogen atoms were used to calculate the electron temperature. A non-equilibrium plasma with two very different temperatures for electrons and heavy particles was found. The spectroscopic study allowed us to explain the experimental results of the LPG conversion and its dependence on the plasma conditions, resulting in optimizing the H2 formation.

Ventilated façades are among the existing measures to reduce the energy demand in buildings. The combination of this passive heating and cooling strategy with photovoltaics (PV) can drive new buildings towards the current European targets near or even to net zero energy Buildings (nZEB). The present work studies the thermal behavior of the PV integrated ventilated façade applied in the nZEB known as “LUCIA” (acronym in Spanish for “University Centre to Launch Applied Research”) at the University of Valladolid, Spain. The aim is to evaluate the interest of recirculating indoor air within the façade during winter, as an alternative to the present preferred operating mode during the target season, in which the façade acts as further insulation. First, the radiant properties of the PV façade are measured to use the values in a mathematical model that describes the behavior of the ventilated façade in its current operating mode in winter. Then, the solar radiation available, the air-dry bulb temperatures indoors, outdoors and inside the ventilated façade are monitored to obtain experimental data to validate the model. The results show that air recirculation can entail favorable heat gains during 10% of winter, being this alternative preferable to the present operating mode when outdoor temperatures are over 18.4 °C.

This article presents an original study on the impact of climate change and the area of windows Awi (factor X1), the thermal transmittance coefficient of windows Uwi (factor X2), and the coefficient of total solar transmittance factor of the glazing ggl (factor X3) on the index of annual usable energy demand for heating EUH (function Y) of a single-family residential building in the climatic conditions of Bialystok (Poland), which were loaded with an equal gradual increase in average monthly external temperature by Δθe,n (factor X4). Based on the results of the computational experiment, a deterministic mathematical model of this dependence was developed, and the effects of selected factors on the Y function were analyzed for the considered climatic conditions. Moreover, in cases of selected variants, the influence of the energy source on the amount of final energy used and CO2 emissions was studied. It was found that an increase in the average monthly external temperature reduces the EUH of the tested building by 8.4% per every 1 °C of increase in Δθe,n. The reduction in CO2 emissions as a result of climate change is visible for systems with low efficiency and high emission factors (wood boiler), while in the case of pro-ecological high-efficiency systems (with a ground-source pump heat) it is inappreciable. Due to the need to decarbonize buildings, knowledge about the impact of the properties of windows, which are the weakest element in terms of heat loss through the building envelope, as well as the type of heat source on heat demand and CO2 emissions, is very important for engineers and designers when making the correct decisions.

The aim of the study was to develop a nationally universal method for estimating the solar resources and to assess, at the municipality scale, the suitability for photovoltaic development based on the implementation of GIS&T (Geographic Information Science and Technology), multi-criteria analyses, and spatial data gathered from the National Geodetic and Cartographic Resources. The developed method is based on the use of digital topographic data and data gathered by means of modern remote sensing methods as a point cloud from airborne laser scanning. Based on studies in the literature, the formal and legal conditions applicable in Poland were discussed. The sets of constraints and factor criteria have been created as a base for evaluating the suitability of a chosen municipality for photovoltaic farms’ emplacement. Weight calculations in a multi-criteria method—an AHP method (analytic hierarchy process)—were applied. In the multi-criteria analysis, 27 constraints and 13 factors were included. Undoubtedly, a utilitarian feature of the developed method is the calculation models allowing full automation of the process of spatial assessment of municipality territories for photovoltaic farms’ development. Furthermore, calculation models can be easily adapted to some specific conditions that occur in the analyzed municipality territories. The results obtained confirm the significant usefulness of the implemented approach in the context of the spatial suitability assessment of photovoltaic development at the municipality scale.

The increasing global temperature has induced many states to limit carbon dioxide emissions. The European Union (EU) promotes replacing boilers with heat pumps. However, in countries where electricity is mainly supplied through fossil fuel combustion, condensing gas boilers may prove to be more ecological heat generators. Although this problem was investigated in a particular situation, an algorithm can be applied elsewhere. The running expenditures for the following different heat generators that are available in a location were estimated: water heat pump, brine heat pump, air heat pump, condensing gas boiler, condensing oil boiler, district heat network, and electrical grid. Furthermore, carbon dioxide emissions from local and distant sources were evaluated. The computations were based on hourly averaged external temperature measurements, which were performed by the Institute of Meteorology and Water Management—National Research Institute (IMGW-PIB) in a weather station in Białystok (Poland) for a ten-year period. Compared with a condensing gas boiler system, the air-to-water heat pump has higher operating costs and higher CO2 emissions. The brine heat pump (closed-loop ground-source heat pump) has lower operating costs, but higher CO2 emissions than the gas boiler system. The water heat pump (groundwater source heat pump) has the lowest operating costs and CO2 emissions of all the systems studied in this paper.

In this paper we show the advisability of usage of solar collectors for domestic hot water (DHW) preparation in buildings located in two countries: Poland and Spain. The analysis was conducted for a single-family house with horizontal roof. During the calculations we took into account factors depending on the building location such as national rules, climatic conditions, cost of system installation, and fuel and electricity prices. Based on the total design heat losses and demand for DHW, the demand for usable energy for heating the buildings and DHW preparation was calculated. A gas boiler was selected as the heat source of the building, and solar collectors (flat-plate and vacuum pipe) were chosen as the source of DHW preparation. Installation investment costs and annual operating costs have been stamped. Calculations show that for buildings located in Spain, heat losses were 36.5% lower and the demand for thermal power for DHW was 59.5% lower than for buildings located in Poland. Annual operating costs of the heating installation for both buildings were at similar levels, due to high fuel prices in Spain, while the operating costs of DHW installations were 28.2% higher for locations in Poland. The results show that the use of solar collectors in Poland is economically justified.

In order to fulfill the European Energy Performance of Buildings Directive (EPBD) requirements regarding the reduction of energy consumption in buildings, great attention is paid to primary energy consumption. Wind energy is considered a type of primary energy. The analysis of the literature has revealed that wind energy is evaluated by different methods. Therefore, the aim of this article is to calculate the effect of the parameters of wind sources and wind speed on the primary energy factor of wind turbines. In order to achieve this aim, the primary energy factor of investigated 100 wind turbines and 11 wind farms operating in Lithuania was calculated. The results of the investigation show that the difference in the non-renewable primary energy factors between wind turbines with regard to their capacity is 35%. In addition, primary energy factor (PEF) values depend on geographic location and climate conditions. This paper provides a recommendation that the EU energy efficiency and renewable energy directives and regulations of all EU member states should use the same or, at least, a very similar methodology for the calculation of the primary energy factors of renewable and non-renewable energy sources.