Marek Telejko

Providing comfortable environmental conditions in buildings requires energy. Thermal comfort depends on many factors, and successful prediction of thermal sensations based on physical parameters of indoor environment is a challenge. However, the issue is of significant importance because HVAC (heating, ventilation, air conditioning) systems consume considerable thermal and electrical energy and should be operated most efficiently to reduce energy needs while maintaining thermal comfort conditions. It is especially vital in intelligent buildings whose systems and services are large energy consumers. In this paper, a modified thermal comfort model (based on the large-scale questionnaire study conducted on intelligent buildings) is developed. It considers the impact of carbon dioxide, which was observed to be associated with higher thermal sensations with rising CO₂ levels. The modification was based on the Box–Behnken method, which has never been performed in such studies. Modified correlations for PMV and PPD indexes proved more accurate than in the original model. Moreover, implications of the modification of this model with regard to energy consumption are discussed; however, this issue proved to be quite complicated as it involves not only input data of the physical indoor parameters but also subjective preferences of the respondents.

The aim of this study is to develop a universal method for the unequivocal selection of the optimal combination of components determining the energy efficiency of buildings by means of an introduced global building energy consumption indicator. The basis of this method is a multi-criteria optimization of the components influencing the energy efficiency of buildings. The method requires the development of a detailed description of the set of components influencing the energy efficiency of buildings and the definition of the analysis criteria. The following analysis criteria were adopted: relative annual demand for final energy, cost, durability, and investment outlays payback time. The normalized values of these criteria are calculated in relation to the structure of a reference building. The proposed method makes it possible to explicitly indicate the most advantageous solution from the point of view of the weighted share of the individual criteria. The verification of the method was presented on the basis of the thermo modernization case study analysis for the adopted reference building. As a result, the most advantageous variant of modernization was determined, defined by the lowest value of the global building energy consumption indicator. A high effectiveness of the proposed method has been shown in relation to both the selection of the modernization option and the assessment of the individual component share in each modernization solution.

Thermal comfort affects not only the well-being of the occupants of a building but also the effectiveness of their learning and work efficiency. It can be disturbed if the ventilation airflow is increased when improving indoor air quality. When natural ventilation is used in the fall and winter period, the supply air temperature is low, resulting in a lack of thermal comfort. In existing buildings, there is often no place for mechanical ventilation; hence, decentralised façade ventilation units are increasingly used. The article presents an analysis of thermal comfort in rooms with this type of unit equipped with heat recovery exchangers of different efficiencies. Studies have shown that the alternating supply/exhaust airflow and the related unevenness of air streams flowing through the heat accumulator cause an inflow of low-temperature air, resulting in thermal discomfort. The highest value of the PMV index was −1.6, and the lowest was −4.1, which means that 54.8 to 100% of the occupants are dissatisfied with their thermal comfort. This means there is a need to change the construction of inlet/exhaust vents so that the stream of supply air is not directly parallel to the floor. In addition, the use of an air heater should be considered.

Due to the spread of the SARS-CoV-2 virus, most countries have tightened their public health policies. One way to limit the spread of the virus is to make mouth and nose cover compulsory in public spaces. The article presents the impact of wearing masks on the perception of thermal comfort. The following masks were analysed: FFP2, cotton, medical, PM2.5, half-face protective shield plastic and full-face protective shield plastic. The research was carried out for two scenarios of an ambient temperature: −20 and 30 °C. A thermal manikin was used for the tests. In the case of when a temperature equals 20 °C, the dry masks increase comfort, both general and local, while wet masks reduce comfort. On the other hand, at 30 °C, only wet masks do not increase discomfort. In addition, moist masks require less heat flux to achieve a certain skin temperature. However, it should be remembered that it is not advisable to wet the masks from the health point of view.

Mountain accident casualties are often exposed to cold and windy weather. This may induce post-traumatic hypothermia which increases mortality. The aim of this study was to assess the ability of warming systems to compensate for the victim’s estimated heat loss in a simulated mountain rescue operation. We used thermal manikins and developed a thermodynamic model of a virtual patient. Manikins were placed on a mountain rescue stretcher and exposed to wind chill indices of 0 °C and − 20 °C in a climatic chamber. We calculated the heat balance for two simulated clinical scenarios with both a shivering and non-shivering victim and measured the heat gain from gel, electrical, and chemical warming systems for 3.5 h. The heat balance in the simulated shivering patient was positive. In the non-shivering patient, we found a negative heat balance for both simulated weather conditions (− 429.53 kJ at 0 °C and − 1469.78 kJ at − 20 °C). Each warming system delivered about 300 kJ. The efficacy of the gel and electrical systems was higher within the first hour than later (p < 0.001). We conclude that none of the tested warming systems is able to compensate for heat loss in a simulated model of a non-shivering patient whose physiological heat production is impaired during a prolonged mountain evacuation. Additional thermal insulation seems to be required in these settings.

The paper analyses the indoor environment in two modern intelligent buildings located in Poland. Measurements of air and globe temperatures, relative humidity and carbon dioxide concentration in 117 rooms carried out in the space of 1.5 years were presented. Thermal comfort of the occupants has been investigated using a questionnaire survey. Based on 1369 questionnaires, thermal sensation, acceptability and preference votes were analysed in view of their interdependency as well as their dependency on operative temperature, which proved to be very strong. It has been found that the respondents did not completely rate thermal comfort and indoor environment quality as very high, although the overwhelming sensations were positive. Apart from the operation of heating, ventilation and air conditioning (HVAC) systems, this might have also been the cause of individual human factors, such as body mass index, as tested in the study, or the finding that people were generally in favour of a warmer environment. Moreover, thermal environment proved to be the most important element for ensuring the well-being of the occupants.

A large number of single-family and multi-family buildings, managed accommodation facilities and institutional buildings both in Poland and throughout Europe are equipped with a natural ventilation system. The operation of this system depends, among other things, on weather conditions, and the system itself is prone to design and operational errors. The analyses of the functional programme of typical flats in multi-family residential buildings as well as of single-family houses indicate that in certain rooms, such as kitchens and bathrooms, the values of the basic microclimate parameters can differ significantly from the parameters' values of the remaining parts of the flat or building. Kitchens and bathrooms particularly require appropriate ventilation. In their day-to-day operation, these rooms are exposed to a more elevated level of relative humidity than other rooms in the flat or building. The paper presents the results of the study conducted in autumn and winter in five flats located on different floors in three multi-family buildings in Poland. All the flats under study were fitted with a natural ventilation system with exhaust ducts in their kitchens and bathrooms. The outdoor air was supplied through window vents installed in the window frames in the selected rooms. Special attention was given to the variability in the levels of relative humidity in these rooms. However, the variability in the indoor air temperature as well as the concentration of carbon dioxide were also considered in the analysis. Only buildings with a natural ventilation system and windowless bathrooms were selected for the study. The results of the analysis showed an elevated level of relative humidity persisting in the rooms in focus throughout the entire period of the study. This salient fact should be noted, since the elevated relative humidity levels combined with the relatively high temperature of the indoor air kept in such rooms in winter are conducive to the development of moisture of the partitions, and in extreme cases, to the development of mould fungi on their surface.

Thermal comfort determines the state of satisfaction of a person or group of people with thermal conditions of the environment in which the person or group of persons is staying. This state of satisfaction depends on the balance between the amount of heat generated by the body's metabolism, and the dissipation of heat from the body to the surrounding environment. Due to differences in body build, metabolism, clothing etc. individuals may feel the parameters of the environment in which they are staying differently. Therefore, it is impossible to ensure the thermal comfort of all users of the room. However, properly designed building systems (heating, ventilation, air conditioning) allow for creating optimal thermal conditions that will evaluated positively by the vast majority of users. Due to the fact that currently we spend even 100% of the day indoors, the subject becomes extremely important. The article presents the evaluation of thermal comfort in rooms heated with a tiled fireplace with the function of accumulation of heat using the PMV (Predicted Mean Vote) and PPD (Predicted Percentage Dissatisfied) indices. It also presents the results of studies, on the quality of the micro-climate in such spaces. The system of heating premises described in the article is not a standard solution, but is now more and more commonly used as a supplement to the heating system, or even as a primary heating system in small objects, e.g. single-family houses, seasonal homes, etc. The studies comprised the measurements and analysis of typical internal micro-climate parameters: temperature, relative humidity and CO₂ concentration. The results obtained did not raise any major reservations. In order to fully assess the conditions of use, the evaluation of thermal comfort of the analyzed rooms was made. Therefore, additionally the temperature of radiation of the surrounding areas, and the insulation of the users' clothing was determined. Based on the data obtained, the PPD and PMV indices were determined according to EN ISO 7730: 2005 Ergonomics of the thermal environment - Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria [1]. The obtained PMV values did not fit within the limits of thermal comfort, and the percentage of people dissatisfied reached almost 20%.