Issue 1/2008

The article informs about the course and character of the heating season 2006/07 in Prague. From the climatic elements measured at Praha-Karlov observatory the quantity values have been determined that are necessary for the calculation of heat demand for heating by degree-day method for the indicated season and its demand factor has been evaluated in comparison with the previous period and with the fifty years normal’s. Further selected data finish drawing the climatic conditions in Prague and sum up the weather character in the course of this period in the whole Czech Republic.

The article deals with the hydraulic behaviour of radiator control valves fitted with P regulator at piping network. It draws the attention to changes and certain special characteristics based on the fitting of the P regulator and the requirement to retain the valve control capability.

In the article the basic attributes are indicated of the new way of building technical equipment operation, representing a component of the Facility Management methodology. The accent is put on the reasons and characteristic process exercise signs and their content at business conception of this activity.

Operative temperature for the evaluation of conditions, creating the environment conditions for human heat production, includes only three quantities: air temperature, mean radiation temperature and air flow velocity. It’s a matter of opinion, whether any combination of these parameters meets the human requirements. The answer is brought by Fanger PMV-PPD model analytic solution. In the article the calculation for MS Excell processor is compiled and used for the solution of specified tasks. The algorithm and the calculation procedure may be used by designers or by equipment critic.

The staphylococci are the worldwide most widespread bacteria transferred by air. Inside of different spaces (metro stations, hospitals, offices, households) and at outdoor environment the staphylococci concentration in the atmosphere was monitored with the aim to find out how the staphylococci concentration is affected by ventilation. Most staphylococci were found out in the patient’s waiting-rooms, followed further by patient’s rooms at hospitals, spaces at metro stations, households and offices. The lowest concentrations were found out in the outdoor atmosphere. The concentrations of staphylococci in the atmosphere depended on the number of persons in the rooms and they were not affected by the air flow velocity and HVAC use. From the point of view of staphylococci occurrence in atmosphere the windows ventilation is regarded as an important hygienic measure.

Information is presented about the new decree of the government the part of which is the chapter about protective drinks. The new approach to the offering of these drinks at work is explained. The authoress acquaints the readers about splitting the waters into groups according to the quantity of dissolved solid substances and offers the survey of accessible waters and their overall mineralisation.

The article sets itself the aim to compare the operation economy demandingness of the swimming pool hall hot-air heating. For the comparison with the basic variant based on the real condition the system modifications in the form of higher recuperation effectivity, volume flow and input air temperature changes have been used.

The needlessness of aluminium foil installation on the wall behind a heating radiator is exemplified using mathematical methods. The model case is based on the theoretical value of foil emissivity, which is valid for a very limited period, after which it decreases rapidly.

At present the standard calculation methods manage to describe the static state of large-surface systems and to determine the energy output per surface unit. They are not able to provide the survey of the system behavior in the course of the year, especially during the transition period. Therefore it is right to design the large-surface systems with the use of computer simulations. The simulation results enable to design and regulate the large-surface radiant systems more effectively. From the operation of a few of large-surface systems installed in the Czech Republic and from the experience of operating engineers some principles and recommendations result for designing and operating the above indicated systems.

The article deals with heat accumulation in the water storage tank. Heat source of the storage tank is a heat pump. Medium temperature stratification in the storage tank is described. Models that are used to stratification solution are also introduced.

The article summarizes the main legislative and normative regulations related to flat ventilation in the Czech Republic. The authors state correctly that unambiguous rules concerning flat ventilation don’t exist in the Czech Republic. For expressing the impact of ventilation on the carbon dioxide concentration (produced by persons) in the flat the Contam 2.4 programwas used by the authors.On the example of two-room flat the expected values of carbon dioxide concentrations are determined by calculation based on this program for different ventilation variants and for different flat occupancy by persons in the course of 24 hours of simulated flat operation. At the article conclusion the proposal of the air flow rates is indicated for some operation modes of hybrid flat ventilation, including the idea of ventilation output regulation possibilities.