A physical model of ventilation of a fitness hall has been developed under conditions of varying visitor load and intensity of physical exercise. The ventilation rate of a fitness room and required amount of supply ventilation air when forming comfortable microclimate in a room under conditions of different intensity of physical exercises were determined. The results of experimental and theoretical studies of dependence of multiplicity of supply and exhaust ventilation depending on the number of visitors to the fitness hall, taking into account intensity of their physical activity and the value of internal air temperature are presented. The method of determining the volumetric and mass flow rate of supply ventilation air and the ventilation rate depending on temperature of the indoor air, carbon dioxide concentration, atmospheric pressure, number of visitors, their gender, age and intensity of physical exercises has been improved.

Providing the required indoor comfort at minimal operating costs is the main objective of every HVAC system.However, despite the fact that in theory, each design effort promises to deliver the design flow at each heating or cooling unit, in reality this is not happening too often.The role of balancing is to obtain the design flow at each terminal unit, by installing some specialized valves and applying a coherent procedure of setting and adjustment.This paper presents a simple hydronic balancing simulator, implemented in a Microsoft Excel spreadsheet.The model uses static STAD balancing valves, provided by the Swedish manufacturer Tour Andersson.The main purpose of the simulator is to obtain a learning tool for students or young engineers, allowing them to observe and understand the circuits interactions when running balancing procedures.

The air temperature in school buildings significantly affects the ability of students and teachers to focus on the educational process. Students usually begin to feel an increase the temperature in room. The purpose of this study is to find the limit of the temperature rise in the classroom when people no longer feel the temperature rise in the room. For this reason, several experimental measurements of indoor air parameters were carried out: air temperature, relative humidity and carbon dioxide concentration. Measured temperature differences and individual subjective ratings of audiences determined the dependence using mathematical statistics, from which can be determined the critical level of increase in air temperature at which people no longer perceive the change in air temperature.

The topic of classroom ventilation in schools has been very topical in recent years. Several scientific and professional studies points to insufficient ventilation in classrooms, which results in lower concentration of pupils on lessons and earlier fatigue. In our study were analyzed the three methods of classroom ventilation during the pause between teaching hours. Air quality investigated was using the measured course of carbon dioxide (CO2) concentration. CO2 concentration measurements provided were by in three stages. In the first stage, ventilation provided was only by infiltration through leaks in the building structure and by opening the door of the classroom to the corridor during the pause between school hours. In the second stage, ventilation provided was by opening the windows of the classroom doors during the pause between school hours. In the third stage, ventilation was provided by a ventilation recuperation unit installed in the closed window through the between school hours. Based on the measured evaluation values of CO2 concentration and calculated values of CO2 production it is possible to state that in our case was from the point of view of air exchange very effective natural ventilation. From an energy point of view however, is effective mechanical ventilation using heat recovery.

The paper documents the determination of the required volumetric air flow of the ventilation unit for the purpose of ventilating the selected lecture room. The contribution briefly characterizes the legislative requirements valid in Slovakia and Poland. Particular attention was paid to the regulations of the Ministry of Health, Ministry of the Environment, Ministry of Transport and Construction of the Slovak Republic and regulations of the Ministry of Education and Sport, Ministry of Infrastructure and European standards. In the paper is documented the experimental measurement performed in the lecture room is also documented. The resulting values of the volumetric air flow required for the ventilation of the lecture room, calculated according to legislative requirements, are compared with the value calculated on the basis of the measured course of the carbon dioxide concentration.

In order to design a ventilation system based on the volumetric airflow rate, which will ensure satisfactory indoor air quality and, at the same time, do not oversize the system, it is necessary to know the quantities of pollutants emissions. The concentration of produced pollutants allows the calculation of the required fresh air volumetric flow rate. Two previous published studies are analysed in this article, whose results complement each other. From the calculated values, the graphical dependence between the required fresh air volumetric flow rate and the level of physical activity was developed. It was noticed that, according to the Slovak and Romanian legislation, for the studied gym, there is insufficient air ventilation. At an allowed maximum CO 2 concentration level of 1,000 ppm, the required fresh air volumetric flow rate, according to legislative requirements, will ensure a percentage of only 75.59% to 23.25% of the necessary rate (depending of the type of physical activity). For a lower allowed maximum CO 2 concentration level, the ensured fresh air volumetric flow rate will be even smaller. The aim of the article is to contribute to the development of healthy environments in fitness centres and gyms and to optimize the design requirements for their ventilation systems.

In construction, the emphasis is currently on high energy efficiency of buildings. A ventilation system ensuring the indoor air quality has a significant share of energy consumption in buildings. Open fire sources, such as gas stoves and candles result in the air pollution in the indoor environment that causes more intensively operation of ventilation systems. The aim of this research is to quantify the pollutants arising from the burning of a randomly selected wax candle that commonly is used in households. Experimental measurements were performed with a special regard to carbon dioxide (CO 2 ) production. The weight loss of the wax during the burning of the candle was has been measured and subsequently the production of CO 2 was estimated using a chemical formula. Based on the amount of CO 2 produced, the intensity of air exchange using ventilation system has been calculated to achieve the required quality of the indoor environment. The calculated air volume flow rate required to remove the pollutants generated during the burning of the candle is in this case approximately 54% of the air volume flow required per one person.

As part of the research entitled "Experimental determination of the optimal amount of air in a selected room in Ukraine based on measurements of carbon dioxide concentration", an experimental measurement was performed in a selected school room in Ukraine. The aim of the experimental measurement was to determine the course of air temperature, relative humidity and carbon dioxide concentration during the teaching process. From the carbon dioxide concentration curves, it is possible to calculate the required ventilation intensity in the room. This article documents the results of measuring the air temperature and the carbon dioxide concentration in the room, as well as the reactions of people in the room to the air quality.

To design a ventilation device, it is necessary to know the required air volume flow to ensure the quality of indoor air. Within the indoor air quality research at Lviv Polytechnic, experimental measurement of carbon dioxide (next CO2) concentration and air temperature in a selected room performed was. During the measurement, students were in the room, who carried out the subjective air quality assessments in the form of questionnaires. From the obtained measurement results, the current and the required air exchange were calculated. Furthermore, the required air exchange was calculated, using the total weight of the persons situated in the room. An analysis of the measured parameters of indoor air and a subjective assessment of indoor air quality performed was in this work. From the analysis of measured and calculated values of air parameters, it confirmed that the rate of increase of the CO2 concentration to the weight of the people in the room is directly related. The analysis of the subjective evaluation confirmed that indoor air quality also affects the accuracy of subjective assessment. By comparing the method of calculating the required air volume flow in the room according to the measured CO2 concentration and the method of calculation according to the weight of persons, an average deviation of 2.16% found was.

The application of demand-controlled ventilation is one of the ways, how to reduce energy consumption in residential buildings. The main producer of pollutants in these types of buildings is human being and its activities. The most common measurable air parameters that can be characterized the level of air degradation in rooms are the concentration of carbon dioxide (CO2), air temperature and relative humidity. The aim of our research was to monitor and evaluate these air parameters in real conditions of apartment usage. As part of the research, the experimental measurements were carried out in a selected apartment, where the concentration of carbon dioxide CO2, air temperature and relative humidity were monitored in individual rooms. During evaluating the monitored air parameters, their maximum and minimum values were evaluated. The achieved research results can be applied in computer simulation the operation of a ventilation system in the apartment in order to increase the energy efficiency of the HVAC system while maintaining the required indoor air quality that is necessary for healthy living.

Indoor air quality is a key aspect of people staying inside buildings. Combustion processes have been identified as one of the most important sources of pollutants in the indoor environment. Proper HVAC design must account for all sources and variations in their intensity, such as also the burning of candles, which produce not only increased amounts of carbon dioxide as a result of the combustion of the organic matrix, but also often dangerous organic substances. On the other hand, the candle burning represents an energy source as well. This article deals with the study of thermal decomposition of selected candle material using methods of thermal analysis - thermal gravimetric analysis (TG) and differential scanning calorimetry (DSC). The wax material analyzed was identified as a mixture of palm stearin and paraffin. During the candle wax material heating, the energy up to 772.6 J per 1 g of material can be released in dependence on the heating rate.

The main goal of the work was the measurement of photovoltaic panels on a family house in the village of Lucka in eastern Slovakia during 4 months. The panels were mounted on the south side of the building at a slope of 26 degrees. The measurement took place every day only during sunshine. Subsequently, the comparison of these actually measured values with the calculated values from the PVGIS software, which also serves to calculate photovoltaic panels. Photovoltaic panels were measured in the months of April, May, June, July in 2021. As was mentioned, the measurement took place only during sunshine, i.e. when the sun's rays hit the photovoltaic panels. From these measurement results, we will find out how much electricity we will actually produce in these months and how much the software will "produce" if we enter the same parameters for the location and type of photovoltaic panels as for a family house.

An important parameter that affects indoor climate of buildings and also ventilation heat losses and gains is the speed of air change between the outdoor environment and the interior of buildings. Indoor air quality is therefore significantly associated with ventilation. Quantification of air change rate is complicated, because it is impacted by many parameters, the most variable of which is air flow. This study focuses on the determination and comparison of air change rate values in two methods by quantification of the aerodynamic coefficient Cp = Cpe − Cpi, so-called “aerodynamic quantification of the building” and the methodology based on “experimental measurements of carbon dioxide”. The study describes and takes into account the effect of wind, building parameters and air permeability for the building using “aerodynamic quantification of the building”. The paper compares these calculated results with the values obtained from experimental measurements method of carbon dioxide in a selected reference room in apartment building and evaluates the accuracy of the prediction of the air exchange rate obtained by these methods. At higher wind speeds the values of air change rate with considering the effect of openings are closer to the values obtained based on experimental measurements of carbon dioxide and the difference between the values without considering the effect of openings increases significantly.

In recent years, the number of gyms all over the world has increased. One of the major problems in the case of gyms is to provide the required quality and quantity of fresh air. For this purpose, several experiments have been conducted inside a gym, where athletes have performed carefully selected sets of exercises during individual measurements. Using the measured air parameters, the carbon dioxide (CO2) generation rate was calculated. The obtained results were compared with other existing laboratory studies and the concordance was very good, especially for lower physical activity levels, where other recommended methods in the literature usually operate. For higher levels of physical activities carried out in the gym, the obtained results are also very promising for future research, as such data is scarce. A graph was created, showing the dependence of the CO2 generation rate and the required volumetric air flow rate, respectively, on the level of physical activity. From the calculated volumetric air flow rates for different levels of physical activity we were able to assess the current state of the applicable national legislation in this domain. The results have pointed out the need to revise these national regulations, in preparation for new specifications regarding the fresh air ventilation rate in gyms.

One of the main tasks around the world is to reduce energy consumption with constant consumer comfort. The hot water supply system uses a significant part of thermal energy and requires no less attention than the heating or ventilation system. The amount of heat loss from hot water distribution systems is of great importance for the energy consumption of buildings. In winter, part of this heat is used for space heating, in summer they are unused and is considered as lost heat. For this reason, this paper considers the influence of water velocity in the pipe, pipe size, and water temperature on the total heat losses in the insulated hot-water distribution system. The data are presented in tabular and graphical form. A graph of the dependence of the amount of heat loss on the temperature and velocity of hot water is obtained.

The paper presents a simple way to study and numerically analyze the 2D temperature field in a square cross section of a beam.A new software tool was built and used for this study, using as the main calculation method the finite difference method (FDM).The steady state heat transfer through a body without internal heat sources was considered and the boundary conditions of the first kind (Dirichlet) were applied regarding the values of temperatures on the delimiting surfaces of the body.The solution of the linear equation system (LES) was obtained using the Solver tool from the Microsoft Excel® software application, finding the numerical image of the temperature distribution in the square cross section.Also, all the numerical results have been translated into a graphical form, for a more intuitive view.

The article presents the results of the investigation of the influence of natural and mechanical ventilation in a passenger compartment and in a driver's compartment on the air flow around the bus. The experimental research was carried out in aerodynamic tunnels. Based on the measurements, the air velocities distribution in the boundary layer was determined. Furthermore, the effect of natural ventilation of the interior space on the thickness of the air boundary layer was analysed. The results are presented in the form of distribution diagram and analytical dependencies. The aim of this research was to define the thickness of the boundary layer when the air flows through a vehicle model.

Air change rate is an important parameter for quantification of ventilation heat losses and also affects the indoor climate of buildings. Indoor air quality is significantly associated with ventilation. If air change isn't sufficient, trapped allergens, pollutants and irritants can degrade the indoor air quality and affect the well-being of a building's occupants. Many studies on ventilation and health have concluded that lower air change rates can have a negative effect on people’s health and low ventilation may result in an increase in allergic diseases. Quantification of air change rate is complicated, since it is affected by a number of parameters, of which the one of the most variable is the air-wind flow. This study aims to determination and comparison of values of the air change rate in two methods - by quantifying of aerodynamic coefficient Cp = Cpe - Cpi – so called aerodynamic quantification of the building and the methodology based on experimental measurements of carbon dioxide in the selected reference room in apartment building.

The aim of the research is to analyze the water demand in apartment building calculated according to the state regulations of Poland, Czech Republic, Romania, Slovak Republic and Ukraine and to compare them with the results of experimental measurements in apartment building. Poland and the Czech Republic are characterized by the minimum average coefficient of water demand for residents of the houses with local hot water preparation. For Romania, Slovak Republic and Ukraine this value is higher by 20, 35 and 110–135% respectively. Czech Republic has the lowest values of theoretically calculated daily (minimum, average and maximum) water demand. These values are higher for Romania – by 38.9, 15.3 and 9.7%; Slovak Republic – by 35.2, 34.7 and 34.9%; Ukraine – by 114.8, 101.4 and 109.6% respectively, as compared with water demand in Czech Republic. The average daily water consumption in an apartment building, measured experimentally, corresponds to the normative value of the specific water demand adopted in the Czech Republic. Maximum daily water demand exceeds the estimated value and corresponds to the maximum coefficient of the daily variation in water demand, which equals 1.63.

In this paper, the partial results of the investigation of the interrelationship of individual parameters of indoor air - temperature, relative humidity and CO2 concentration, obtained during the experimental measurement, are presented. The experimental measurements have been performed in a selected room, where three separate lessons with three different groups of people have been conducted. During these measurements, the processes of temperature, relative humidity and CO2 concentration have been recorded. Also, people involved in this investigation have made their own evaluation. They, have been asked for opinion about the internal air quality at the beginning and at the end of the experimental measurement.