Issue 1/2006

The article informs about the course and character of heating period 2003/2004 in Prague. On the basis of climatic data measured at the Praha-Karlov observatory the values of quantities necessary for the calculation of heat demand for heating were determined by the degree-days methods for the indicated period and its energy demandingness was evaluated in comparison with the previous heating period and with the fifty-year averages. Further selected data illustrate the climatic conditions in Prague and outline also the weather character in the course of this period in the whole Czech republic.

In the article, the problem of absence of even a minimum level of ventilation rate requirements in industrial halls heated by high intensity gas radiators is discussed. Installing heat recovery units in these situations were considered as one of the possible solutions. Simulations of such combinations based on the FLUENT software were carried out. As a result, the optimum locations of supply and exhaust outlets of the air system were defined.

A method of the indoor comfort evaluation by the methodology as used in Slovakia is demonstrated on two examples of measurements of the indoor environmental conditions in industrial halls. For the reader, the results are interesting and valuable as they represent the original work of the author. The methodology of results’ evaluation for the Czech Republic is defined in the Government Decree No. 178/2001 Coll., dated 18. 4. 2001 defining conditions for employees’ health protection at the work place, and its amendment No. 532/2002 Coll., dated 13. 12. 2002, defining among other things the work environment and the workplace hygienic requirements.

The article deals with an experimental determination of the local energy loss at butt-welded, straight polypropylene pipe joints. Values of the local loss coefficient for circular plastic pipe joints are presented for the turbulent flow of pure water. These coefficients, that are important for plastic pipe system designers have not been previously experimentally quantified.

A general conceptual approach to building passive houses in the Czech Republic is presented in this article for the first time. In his approach, the author considers and describes interactive solutions to urban, architectural and structural problems. Included are issues of using modern recuperative ventilation systems, and layered, no-contact insulation of building shells, eliminating the thermal bridges. The overall costs of such passive buildings were assessed to be comparable to those of traditional design.

Air leakage (caused by leaks in building envelope) may markedly influence among others the air exchange in the building, the operation of ventilation system and the heat demand for heating. The contribution indicates the evaluation possibilities of the overall air permeability of buildings, summarizes requirements of building-related technical standards concerning the airtight of buildings and building components and indicates in the form of a parametric study especially the energy effects of high air leakage on a simple example.

The article is based on hourly measurements of temperature, relative humidity and pressure at Praha-Karlov station in 2003. The mean, maximum and minimum temperatures of outdoor air in the course of the day are indicated for individual months. The occurrence frequency of individual air temperatures has been monitored both in the course of the year and in the course of the day, namely at intervals 6 to 14, 14 to 22, 22 to 6 and 0 to 24 o’clock. The functional dependence of the mean specific humidity and enthalpy of outdoor air on its temperature are indicated and the results are compared with measured data.

At the present-day cinema the cinema-goer impression is intensified above all by sound sensation. The submitted article indicates a survey of the most used sound formats for sound presentation at cinemas. High frequency ranges and wide dynamics of sound records require very low values of background noise at cinema hall. The construction structure and the equipment of environment engineering have to be comforted to these requirements. The author recommends the use of verified ways of air distribution with regard to spectator comfort and to noise proper of elements.

In the article the author demonstrates on a concrete case the use of a set of control measures to reduce the contamination of a drinking water distribution system by legionella. For this purpose, the distribution system of building No. 5 of the State Health Institute in Prague was colonized by a quantity of legionella that exceeded the limit of 100 KTJ/100ml imposed by the Regulation No. 252/2004 Coll.

The article deals with sources, harmfulness and methods of dioxins separation from waste gases, carried away to the outside environment. It points to problems of dioxins separation at incineration plants and also to legal restrictions of dioxins emissions, especially in connection with refuse incineration plants operation.

Thermo Active Building Systems (TABS) are very widely used for heating and cooling of the office buildings in many European countries. Utilization of such systems means significant energy savings. The article gives an overview of currently used types of TABS and describes their operation principles. Basic requirements for the installations of TABS in office buildings are also mentioned.

The wick-concept for thermal insulation of cold piping is based on capillary suction of a fiber fabric that diverts condensed water vapor from the pipe surface to the outer surface of the insulation. From the surface of the insulation jacket the water will evaporate to the ambient air. This will prevent long term accumulation of moisture in the insulation material. The wick keeps the hydrophobic insulation dry, allowing it to maintain its thermal performance. The only liquid moisture is kept in the wick fabric. The article presents the principle of operation of cold pipe insulation using the wick-concept in either of two variations: the self-drying or the self-sealing system. Some experiments have been carried out using different variations of the two systems to investigate the conditions for exploiting the drying capabilities of the systems, and the results are given in the article. The results show that variations of these types of insulation systems work for pipes with wall temperatures above 0 deg C and for ambient conditions within common ranges for industrial applications.