Issue 1/2019

This article sums up the issues of the fire safety of air and smoke extraction ducts. The author identifies and analyses the relevant standards, the principal design decisions, the construction details and the fabrication practices that affect the fire safety the most. The practical experience in the field demands much higher attention to this subject: from the standardization bodies, the design bureaus, the construction supervisors and the fabrica tors.

The lowest possible induction is the minimal mixing of the supplied air with the ambient air, which is achieved by, for example, separation of the air stream from the supply outlet with use of screens. However, the air must be supplied appropriately – at a low speed. This ensures minimal overpressure in the area behind the screen. The solution can be used both for single-point and flat-area air supply. The article presents three cases of ventilation of demanding industrial workplaces with requirements to ensure intensive ventilation without contamination from the surrounding dusty environment or cooling of given workplaces. In all the cases, permeable or non-permeable fabrics were used, with distribution holes of a diameter from 200 mm to 400 mm.

The article presents an expert system for automatic detection and diagnostics of failures of air-conditioning (HVAC) units, on the basis of expert rules using continuously collected data. The tool makes it possible to detect badly operated HVAC appliances that either consume more energy than necessary or fail to provide user comfort, eventually operate in a mode unsuitable for their lifespan. This analysis is done without any intervention of a human operator.

The paper deals with modern materials, technologies and their combinations, which can improve energy use in buildings. It describes the technical design and use of a special storage device consisting of PCM heataccumulating panels. The storage panels have an integrated tubular heat exchanger and heating film, so the technology can be used in both passive and active heating and cooling modes. The technology is designed with respect to ecology, i.e. with the ability to use energy from renewable sources, such as photovoltaics, solar collectors and heat pumps. An interesting and unusual possibility is the use of thermoelectric cooling. The research also introduces a measurement of various operating modes, the results of which are useful.inincreasing the thermal ca pacity of buildings and providing hea ting and cooling.

The paper assesses the effect of variation in calculation time steps and load profiles of electric energy on the calculation of the photovoltaic (PV) system annual solar fraction of the consumed user electric energy in a household without considering accumulation. Load profiles of the user energy consumption are difficult to generalize due to their variable nature. A generator of a probable user energy load profile was used for the purposes of PV system balances. The PV system production was calculated in the TRNSYS simulation environment with respect to the time step. The results of the energetic and economic assessment show the importance of using a detailed load profile and a sufficiently short time step for calculating solar fraction of PV system. Finally, a simplifying diagram was developed to estimate the PV system solar fraction of the user energy consumption for fast and practical use.

When designing a range of energy appliances, it is necessary to know the climatic data of the installation site. In our conditions it is possible to take use of the project “Reference Climate Year for the Czech Republic” and obtain the data from the Czech Hydrometeorological Institute for a specific location. This article, which deals with outdoor air temperature, humidity ratio and enthalpy, is based on a generalization made using data for so-called backbone stations of the project.

Climate change will, among other things, affects buildings, technical systems in buildings and built environment in general. This paper deals with the expected future changes of environmental boundary conditions in the Czech Republic. The climatic conditions corresponding to the recent past (the reference period 1960 – 1990) are compared with the expected climatic conditions in 2020–2050, respectively in 2070–2100. Hourly climate data calculated by regional meteorological model are used. The results show a gradual prolongation of the summer season, a significant increase in the number of tropical and summer days, the prolongation of continuous hot spells and the increase in daily maximum temperatures. There will also be a shorter winter season, with a significant decrease of the frequency of temperatures below freezing point. The impacts of change in boundary conditions are then quantified in a case stud y of a model family house.