Issue 3/2005

The article summarises the basic data on temperature conditions and heat demands for heating periods of 2000/01 to 2003/04 in Prague – Karlov. The evaluation and comments on rating the energy demand of individual periods are supplemented by data on temperature extremes and frequencies of occurrence of outdoor air temperatures.

In the article, the author presents fundamental terminology, fire protection codes and explains the importance of considering them in a proper design process of air conditioning systems. He suggests that it is essential for the designer to understand the terminology and be capable of interpreting the code requirements properly so that the installed plant can be operated safely and efficiently from the point of fire protection concerns. Another important goal of the author is his attempt to verify and explain the differences in terminology used by both professions to describe the same phenomena.

The presented article brings the intricate problems of the design of ventilation equipment for health service to the reader. In the Czech republic the adequate legislation is not at designer’s disposal, in existing legal documents the requirements are defined insufficiently and sometimes also antagonistically. The author summed up some problems that have to be solved by the designer and draws the attention to risks connected with the designing of ventilation equipment for health service. The communication represents the introduction to the series of articles dealing with the given subject.

-

There has not been adequate attention paid to residential ventilation in the Czech Republic. Only a small number of dwellings are fitted with modern energy efficient ventilation systems. Among the modern residential ventilation systems, which could be employed in the Czech Republic, belongs the hybrid ventilation system for the moderate climate developed within the framework of the European project RESHYVENT.

Currently, air filters are one of the most critical components of air treatment systems as they decontaminate the air delivered to living space. During the operation, however, the level of harmful surface deposits increases, and at certain times, an uncleaned filter can itself become a source of undesirable contaminents influencing negatively the IAQ of a living space. This is the phenomenon that has been a subject of the current research. The article presents a new, alternative view on indoor air contaminents and filtration requirements. It describes alternative means of filtration and assesses issues of inadequate maintenance and/or long term use of applied air filters. An experimental method of evealuating the air quality by means of chemical analysis and state-of-the-art spectrometer is also described.

Efforts to utilise energy in buildings rationally lead to the development of active façades concepts such as massive walls covered by transparent insulation, photothermal and photovoltaic façades, advanced glazing for the purpose of natural lighting and ventilated double façades. The article focuses on photothermal collectors integrated into the building façade and their use in two typical potential applications in the Czech republic – solar system for heating the warmservice water (WSW) at apartment houses, and solar system for heating the warm service water (WSW) combined with upgrading the heating at family houses.

The article deals with the CFD simulation of heat gain and fluid flow in a double-skin solar energy façade. The south facing 5.6 m high façade, with an air gap width of 63 cm and a total area of 123 m2 has been used as a heat source for an air-to-water heat pump. In the performance simulation, authors focused on investigating the impact of various air gap widths, climate conditions, and shading blinds, on the air temperature and the output heat rate of the façade. Six various situations were simulated using a simplified 3D steady-state model. The calculated result revealed that the output heat rate of the facade could be expected in the range of 8–15 kW and energy efficiency of 14–19 %, depending on the time of year.

The reference information for heating source output determination is represented by the output course of this source in the course of the day in dependence on the required course of indoor air temperature. The solution utilises the quick Fourier transformation and algorithm is built-in into the simulation programme. The use is suitable for example for source output determination at intermittent heating. As an example the calculation is indicated of the relation between the temperature decrease, deciding on operating expenses and the required heating source output, influencing the capital cost of the designed building.

The latest version of ASHRAE Standard 62.2 was formulated to encompass the new hygienic requirements while adopting measures for minimizing the energy consumption of applied ventilation systems. It governs the design and operation of ventilation systems in residential buildings of no more than three floors and used as permanent residencies. The goal of this article is to inform professionals on the resulting new guidelines for the respective ventilation system design. The guidelines are easily understood and provide for design solutions yielding an appropriate IAQ without the need for excessive capital and operating costs. The essential element of the Standard is the method of evaluating the minimal air flow rates of the central ventilation plant and/or those for the individual terminal units. It also contains all the requirements and conditions for appropriate design of such systems.