Issue 5/2015

The paper analyses the energy demand and the operating expenses related to ventilation of classrooms in school buildings, ensuring adequate indoor air quality in accordance with directives of the Czech Republic. The analysis include both natural and forced ventilation and also interrupted natural flow-through ventilation. The paper also contains the analysis of selected local ventilation units, in order to identify the specific financial cost for operating the forced ventilation. It has been found that the total costs related to the operation of the permanent forced ventilation with heat recovery system and defined fresh-air content is by no means essential for the school budget.

The paper follows the 1st part of the series, published in VVI nr. 3/2015. The second part contains description of the concept, functions and schemes of the basic ventilation systems for nuclear power plants with containment and hermetically sealed space. The described solution is common for water cooled and moderated reactors. The author notes that the basic classification of the ventilation systems for the blocks of the new generation is remaining in accordance with the submitted text. The emphasis is put on the knowledge of the technolog y for which are designed the ventila tion systems.

The paper is a third part of the series describing new methods used within facility management. The first part dealt with nature of these methods, the second part followed up with their practical application, legal background and examples from the world. In the third part, the author analyses current trends in organizational models of maintenance processes for operation of technical equipment in general, with emphasis on technical equipment of buildings. He introduces the readers to the development of sophisticated approach towards this fundamental and essential activity and thus reflects the traditional ways of maintenance operations, which are very often random and late in response.

Air pollution caused by dust particles poses a serious problem for human health and environment. The negative effect of the ultrafine dust particles (particles with the size less than 100 nm) on the human health depends for example on the number of particles, specific surface of the particles, respirability and ability to bind other chemical compounds (e.g. PAHs). The paper summarizes findings gained from combustions tests of brown coal in small combustion devices. The combustion tests were performed in typical hot water boilers at the nominal power. The low-pressure cascade impactor DLPI was used for the characteriza tion of the ultrafine particles.

The target of the paper is to inform about the current methodology for determination of the coefficient of thermal conductivity, from values measured in the laboratory, through statistical evaluation by manufacturers, to the design values used in calculations by designers. From the legislative point of view, there is a different procedure used for insulations used for construction applications and for HVAC applications, which often leads to confusion in practice. This is due to both an excess number of regulations and non-compliance with the given procedures on the side of manufacturers.

Calculation of electricity production by photovoltaic systems can be performed by more or less simplified approach. Monthly balance method allows to include the influence of the temperature and solar irradiance into the monthly production calculation with use of the PV module parameters available in the technical datasheet. Individual PV module technologies are compared by the balance method.

An important characteristic of refrigerant is aside of the environmental and safety characteristics also energy efficiency, arising from the thermodynamic properties and determining the energy demands for operating the refrigeration system. In the article, energy efficiency of carbon dioxide is compared with selected refrigerants currently used in the field of refrigeration and air conditioning and advantages of its use and examples of use in the Czech Republic are discussed.

In the year 2015 was issued a big amendment to the Act no. 406/2000 coll. on Energy Management, which took into account the comments of the European Commission and removed some controversial provisions related to the Energy Performance Certificates issuing and other activities of energy specialists. The annotated summary of changes gives the reader an overview of the extent of the changes and points out those, which are fundamentally changing the existing well-established practices.

The paper follows the previous topic of energy efficiency of products used in ventilation and air-conditioning (VVI nr. 4/2014). The aim of this paper is to introduce and explain in a nutshell to the readers the entirely new requirements on the ventilation air-handling units for building services systems, implementing the European Parliament and Council Directive 2009/125/ES, in terms from 1. 1. 2016, respectively from 1. 1. 2018. These requirements do not apply to the ventilation units for residential buildings. The cited regulation approaches the assessing of the ventilation units energy efficiency by entirely new way and evaluates them as a whole, including all the mayor parts, which significantly affect the energy consumption during their operation. Compliance with all the requirements of the regulation will have a mayor impact both on the designing, as well as on the choice of the main parts directly at the manufacturers of the units, who bears the main responsibility for the compliance. The Paper is targeted especially to the designers of ventilation, heating, air-conditioning and cooling, for suppliers as well as investors in the rela ted fields.