Issue 1/2009

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The article deals with an experimental determination of a local energy loss in a connection made by polypropylene and polyethylene duct butt welding. The content reassumes the preliminary experimental work, which results were published in Heating, Ventilation, Installation Journal, 15, no. 1, 2006, p. 15-18. There are determined local loss coefficients in a connection of concrete plastic tubes for series of selected dimensions and magnitude of friction loss coefficients for a straight plastic piping of a circular section for a turbulent flow of clear water, which are important for designers of piping systems from mentioned thermoplastics, presented in the paper.

The article deals with a practical application of a single pipe heating system, which replaced a former „crittal“ radiant ceiling heating. The author describes solution used in this case as well as provable heating energy savings.

The article is focused on the problems of the multiple channel solar chimney, where the channel is divided into the sections. It describes the function of the solar chimney and explains its contribution for saving of operating energy cost of the building. Main part of the article describes the model measurements ofmultiple channel solar chimney during the period 28.8.2007–30.9.2007, that has been realised at Aalborg University in Denmark. It is described the chimney construction, the experimental equipments and the measuring method of the main magnitudes; experiments are documented with the photos. The air temperatures, the air flow rates and the solar radiation were measured. The article contributions are the knowledges of the multiple channel solar chimney experimental measurement, when the air temperature in ventilated room was lower than the outside air temperature. The model used in the experiment was also simulated in the CFD program Flovent 7.1. In the article are presented some plots of the CFD results.

The subject of the article is road tunnels ventilation during fire and follows loosely previous article in VVI 5/2007 „ Smoke control in road tunnel during fire“, that discussed standards and recommendations for ventilation operation in road tunnels in Czech Republic as well as abroad. The article is in the first part focused at the main factors influencing smoke behavior in the road tunnel. In three chapters, is on different parameters (slope, length and wind), illustrated the need of immediate reaction of the ventilation system. Scenarios were calculated by Solvent on models with geometry and performance corresponding to several highway tunnels in Czech Republic as: Lochkov, Valík a Klimkovice. Second part deals with importance of fire tests in relation with fire heat release and the influence of ventilation control strategies on smoke and temperature in the tunnel.

The article deals with a very urgent issue – how to construct buildings in a modern way regarding their inner microclimate and using principles of „cooling without cooling“, i.e. keeping the maximal energetic efficiency of building operation. It also contains explanatory parts that bring the reader into the mentioned field of knowledge. The author describes a number of practical possibilities, brought by the outlined methodology, also with examples of their utilization during building construction and shows to designers and constructors the right and modern ways of making project documentation concepts of all building types.

The article reminds about the main changes, affecting preparation, realization and utilization of structures, that were induced by the new (currently two years in the force of legislation) building act No. 183/2006 Coll. The article emphasizes some simplifying procedures, regarding the town and country planning as well as building permission proceedings. Then main reason for publishing this article is the little awareness of the mentioned legislation changes even among experts who for instance still use some old terms not included in the new act. The article is also an inspiration for the current broad discussion about changes that should be incorporated into the amendment awaited in the next few years.

There are both simple and complex simulation software tools for determination of building energy consumption. The simplest software is mostly intended for a basic calculation of building energy consumption, while the complex sophisticated tools take into account dynamic behavior of building structures and HVAC systems during the year. Determination of result uncertainty range based on inaccurate calculation inputs as well as of the sequence of monitored results classified according to their sensitivity on particular input values is an interesting task. The question is how different the results of the two software groups can be? This paper contains comparison of resulting heating loads in a case study of a family house. Calculations were made in four different software tools: NKN, Energie 2008, IES and ESP-r. The results are also compared to experimentally measured values of annual heat consumption. Monte Carlo method is used for an overall uncertainty and sensitivity analysis.

The paper presents results of a study carried out within a Monitoring of public health focused on the air quality in classrooms in elementary schools. Mass concentration of aerosol particles fractions PM10, 2,5 a 1,0 and basic microclimatic parameters characteristics (temperature, relative humidity and air flow) were measured in selected 14 schools in 141 classrooms totally. Results of supplementary CO2 measurement were used as the air change rate criterion.

Surface concentrations of bacteria were examined on items of daily use and also at places where people gather. Silver nanoparticles with antibacterial effect were put into surfaces of three product groups (children‘s colour pencils, countertops, toilet seats) and consequently, their influence on bacteria survival rate was investigated in a laboratory. There was a significant drop (from 41 to 100 %) in the number of bacteria on surfaces with silver nanoparticles compared to surfaces without them. Benefits of products with silver nanoparticles for a daily use in the human environment are discussed.

The authors report about a successful application of stereo thermometer, which is a device for measurement of globe temperature and radiant temperature asymmetry.

The author deals with legislation defining acceptable methods of hot water supply metering in such cases when the locations of heat source and the place of consumption differ. The author expresses his opinion on advantages and disadvantages of two approaches chosen from the accepted methods.

Operational reliability of HVAC devices strongly affects all economic parameters of the whole building lifecycle. Therefore, elimination of hazards caused by all types of unwanted operational events must be in the focus of everyone involved in building construction and utilization.