Issue 1/2022

The boundary conditions for chimney design are an extensive topic. Such design includes not only the requirements related to the appliance and fuel type but also the relation to the building for which the chimney is designed. This article discusses the conditions that must be considered in the design of a chimney, including the impact of neighbouring buildings and fire safety .

The topic of the article is the assessment of the behaviour of the system vessel in the heating system based on numerical simulations. The behaviour of the system vessel was assessed at three different operating conditions, mainly with regard to the speed and temperature fields. The key parameters were in particular the input speeds and the proposed heat output of individual circuits connected to the system vessel.

The paper presents a new methodology for assessment of the overall efficiency of combustion heat sources for the purpose of heating system inspections. The methodology is a part of the new decree under preparation. It takes into account the operating parameters of heat sources, which are objectively detectable directly during the inspection during the opera tion of the source.

In EN 17037 [1], the median value of year-round illuminance is given as the quantity required to determine daylight limit values. Since they are determined according to procedures that may not be generally related, it was necessary to check if this theoretical consideration would be confirmed in practice. The verification of the limit values determined in this way was carried out by long-term illuminance measurements on a model under a real sky. The final version of the model allowed for the measurement of two rooms with an approximate orientation to the north and south. The model was located in the village of Roztoky, on the northern outskirts of Prague. Illuminance measurements were made inside the model and on an unshaded horizontal plane, in the period from April 2018 to December 2020. From the data obtained, the daily illuminance factor for each room was calculated and compared with the theoretical value determined by the model of a uniformly overcast sky in winter. Therefore, it was possible to assess how well the assumptions of the theoretical predictions were met at the time of measurement and whether it was meaningful to use the recorded values for further analysis. Furthermore, the paper evaluates basic statistical values of illuminance, in particular its median over a one-year period. The baseline evaluation was done from a continuous measurement in the period from May 2019 to April 2020, called the measurement year. The statistical files were confronted with the values reported in [1] for the Czech Republic.

The article deals with the issue of the recommended relative humidity in the residential environment, which is related to the production of water vapour from human activity. Water vapour production was monitored in a real family house during the winter season and compared with standard values and data reported in the literature. As part of the monitoring, indoor air quality (IA Q) parameters were also recorded in selected rooms. From the results of the case study performed, it is clear that the indoor air humidification in the residential environment due to human activity is stable during the day. It depends, to some extent, on the behaviour of the occupants, and no significant differences are evident between weekend and weekday water vapour production. A major factor appears to be the dependence of the occupant’s behaviour on outdoor climatic conditions, especially the temperature of the outdoor air. The paper discusses the differences in c limatic conditions in different loca tions of the Czech Republic during the year.

The cybersecurity of building control systems is usually only addressed during the implementation stage, when the operator and the control system supplier meet. However, the basic security features should be defined in the design stage. Designers usually use the excuse that they do not have a partner to address these requirements with – the construction company is not interested, and the operator (or a dedicated responsible person) is not yet known. However, this does not mean that the designer should not be aware of the security aspects and that he should not take them into account, at least in some basic form, in the system design.

The paper focuses on another important source of noise in a heat pump, the axial fan. It discusses the causes of noise generation and the possibilities of its reduction. It also mentions possible methods to calculate the sound po wer levels of axial fans presented in the literature.

Cryptocurrency mining equipment consumes large amounts of electricity. An increase in the efficiency of the equipment operation can be achieved by utilization of the waste heat produced by the mining equipment. The paper describes the energy and economic benefits of operating the mining equipment in a family house. The technical solution and economics of operation is presented for the year 2020, when the mining equipment was used to mine the cr yptocurrency Ethereum.