Issue 5/2006

Thermo Active Building Systems (TABS) are widely used for heating and cooling of office buildings today. Their ability to actively utilize thermal mass of the building construction provides substantial energy savings. Moreover, the fact that TABS work with small temperature difference between heat carrier and conditioned space increases possibility to effectively use so called renewable energy sources. The article addresses operation characteristics of the TABS, shows an example of their installation and pays attention also to barriers that can occur during integration of these systems in building design.

The thermal efficiency of rotary heat exchangers depends on pressure differences existing on face surfaces of the rotor. The air passages of extracted and ventilation air flows are separated by peripheral and radial sealing strips that are not perfectly tight. Air penetrating through this clearance is associated with transferring contaminants and heat that changes the efficiency of heat regeneration. The functional relationship between the pressure differences and clearance air flow is described as based on laboratory and field measurements. Discussed are also the problem with application of code EN 308/1998 for testing and rating of heat exchangers, and the opportunity for it‘s improvements.

The article is devoted to types of glass properties limiting the transmission of solar radiation. In contrast to common reflection glasses, having not the spectral dependence of radiation permeability, the so called chromogenic glazing types are described. These types of glazing achieve a variable radiation permeability in dependence on the wave-length of impacting radiation. This property appears to the observer as a change glass colouring. According to the principles of spectral radiation permeability change, presented in sequence are: thermo-chrome glasses (the spectral radiation permeability change depending above all on glass temperature), gaso-chrome glasses (permeability change achieved by a chemical reaction of gas layer and metal oxide on the inner surface of the gap between the layers in the presence of a catalyst, resulting in colouring change), photo-chrome glasses (darkening of the glass mass itself according to the radiation intensity, instigated by the concentration of certain ingredients during the glass production process – used in optics), electro-chrome glasses (colouring change due to the voltage and direct current effects in the electrolyte layer), and finally glazing with a thin layer of liquid crystals that can best control the relationship between the transmitted energy flow and the needed illumination, thereby reducing costs of buildings cooling load.

In the article author analyzes requirements for location radiators in low-energy buildings and in buildings with a low-demand thermal-technical properties (i. e. standard, classical buildings). On the basis of his own computer simulation and literature data the author proves the rules for radiators locating (under windows) to be also valid for low-energy buildings.

The article explains the specific role the fire ventilation of structures plays in context of solving the overall buildings fire protection design. This problem consists of rectifying the smoke and heat flows in case of fire in a building with the main aim of ensuring conditions for person‘s life and health protection during the period of evacuation. Further aim of this ventilation is to create favorable conditions for firemen at their intervention, and also to decrease the heat stress of the building structure as the construction material damage is decreased significantly by reducing the heat. The article briefly characterizes the individual types of fire ventilation: ventilation of protected escape routes, smoke and heat withdrawel. It describes their basic functional principles on the basis of natural and forced ventilation. It gives reasons for a need to unify calculation methods and design principles with the identical (harmonized) European standards. It also emphasizes the need for fire ventilation designer‘s cooperation with the architect and the building fire security designer and also the necessity of coordinating the operation of fire ventilation working with other fire-fighting systems.

Rise in energy prices in the whole world leads to new views on building ventilation systems control. In the article the author analyzes the possibilities of utilizing the outside air flow variations from the hygienic minimum, energy- advantageous at low and high temperatures of outside air, up to the energy-advantageous reduction of cold or heat supply by an outside air flow change during the spring and autumn seasons. It‘s a matter of a very interesting view on air exchange control in buildings.

The author of the contribution informs on conditions of about two million existing buildings in the Czech Republic built in the course of forty years of 1950 to 1990 by construction systems having predominantly used the technology with prefabricated structural elements – panels. At the same time, he informs about procedures for their repairs and modernizations, including reports on institutions being engaged in the preparation, processing and verification of the technological procedures of repairs and modernizations.