Issue 3/2012

I offer the information concerning the implemented ventilation of the gymnasium in Sokol Hanspaulka to participants of the conference ”Minimal Energy Demands for Quality Environment” in accordance with the central subject thereof. The building that was built in 1941 was revitalized step by step after the property restitution to Sokol in the year 1998. The information concerning the replacement of the coke boiler room with a gas boiler room, and savings achieved was published in [1]. The replacement of fragmenting windows with modern tight windows in the year 2006 excluded the possibility of the natural ventilation with the outside air infiltration through window slots. Opening windows in the winter period is not suitable because of the danger that gymnasts could get chilled. Therefore, the forced ventilation using the unit with the exhausting air heat recovery for heating the supplied fresh air was installed there.

Authors submit the calculation analysis of the operation of the gas consumer (appliance) equipped with the flue gas draft breaker in the space with the outside air decreased infiltration through window slots, in their contribution. They evidenced in the solution that the consequence of such an operation may result in the infiltration of combustion gases from the flue gas draft breaker into the room, and carbon monoxide (CO) accumulates from combustion gases there.

The author describes the protection against noise with the installation of barriers situated close at the equipment of the environmental engineering installed outside, in his article. He introduces with practically usable calculation processes for the determination of the sound loss spreading over the barrier and compares individual processes applied to a specific application. Further, he specifies the effect of the barrier width to the total loss caused with the barrier.

It is necessary to know values of the local resistance coefficient of used fittings for the precise calculation of pressure losses in the HVAC duct distribution network. The pressure loss is often being estimated in the practice, which mostly leads to the wrong design of the fan. There exist many data, which include information concerning the local loss coefficient of fittings of the air ducts; however published values often differ with one another. The local loss coefficient can be determined experimentally through the calculation or with the computer simulation utilization. Authors present possibilities of the simulation used on the basis of CFD for the determination of the local pressure loss coefficient and results of the simulation calculations for specific fittings compare to published values, in their article.

The author opens further discussion concerning the suitability of use fan-coil units or ceiling induction (air and water) units (cooling beams) serving for the office premises air conditioning in administrative buildings, in his article. He analyses merits and imperfections of both systems in detail. He describes the rebirth of induction units, their development, the distribution and the success with their use during recent years, and possibilities whether fan-coil units can remove problems of induction units. He utilizes his own experience as concerns designing and the operation of said systems. He describes their preferences from the viewpoint of the function, possibility to install them in the soffit, costingness of consequential professions as well as impacts in the interior design. As the conclusion, he suggests a question whether fan-coil units have already reached the peak of their use or they shall again find their application in the market in future years.

The author deals with decisive influences that affect the thermal conductivity as a basic property of thermal insulations. He analyses individual influences of temperature, moisture content, and density and explains new terms such as measured, declared and design thermal conductivity

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