P. Kic

Thermal properties of historic rural building materials in Czechia

Due to the different natural conditions, various local natural building materials were used for the construction of rural residential and farm buildings in various locations in the Czech Republic. Currently, it is often a requirement for the modernization of relatively old buildings. The buildings were built with different technologies. Very often only locally available material was used. In many cases, the properties of old materials are not available in the literature. However, it is necessary to know the thermal properties of building materials for the preparation of a reconstruction design. Thermal properties of materials are the basis for determination of heat losses of buildings useful for design of heating systems. The aim of this paper is to compare the research results focused on the thermal conductivity of different old construction materials (stones and rocks) and to show examples of preserved historical agricultural buildings. The results presented in this paper are based on the measurements by the portable instrument Isomet 2104. Authors recognised significant differences between tested materials. The mean values of thermal conductivity m of tested materials: gaize 1.49 W m-1 K-1, artificial marble 1.80 W m-1 K-1, gneiss 2.36 W m-1 K-1, proterozoic shale 2.68 W m-1 K-1, granite 3.66 W m-1 K-1 and quartz sandstone 6.15 W m-1 K-1. Differences between thermal conductivity values of stones and rocks should be respected in calculation of heat balance of new or reconstructed buildings to avoid the problems of the formation of thermal bridges.

Air-conditioning and microbiological environment in the lecture room

The influence of indoor climate on human health has been emphasized in numerous scientific and professional papers (F i s k et al., 2007; M u d a r r i , F i s k , 2007). Some studies dealing with the importance of a suitable microclimate in offices (Seppanen et al., 2006) and at schools (K a r w o w s k a , 2003; G r i s o l i et al., 2012) pointed to the impact of the diseases incidence on the regularity of school or office attendance. Inappropriate microclimate may contribute to a higher sickness rate, and thereby may increase the number of days spent out of office or school (M u d a r r i , F i s k , 2007). In the study on indoor air microbiological contamination in various rooms of university buildings, multiple growth of bacteria and significant increase of mould spores was observed in the afternoons (S t r y j a k o w s k a S e k u l s k a et al., 2007). A w a t et al. (2013) mentioned that the outdoor fungal concentration depends on the locality and season. According to their results fungal concentrations were significantly higher in the rural than in the urban environment. The average indoor and outdoor total fungal concentrations were 608 and 675 CFU.m-3 in the urban environment and 1932 and 1872 CFU.m-3 in the rural environment, respectively. The greatest concentrations were found in the autumn and spring season. Indoor and outdoor concentrations were significantly correlated (P < 0.001). Recent years results (not yet published) of microbial air quality measurements in the University campus and its surroundings have shown that the outdoor air concentration of bacteria was in the range of 110–1010 CFU.m-3 and of yeast and filamentous fungi 170–3890 CFU.m-3, positively depending on air temperature, wind gusts, and amount of necrotic aboveground parts of plants at the place of the measurement, and negatively depending on relative humidity of air. The objective of the present paper was to show the true microbiological situation in the lecture room equipped with the air-conditioning (AC) system. Microbiological contamination was monitored at different operating conditions inside the room. As the inlet of the described AC system is situated in a quiet place, without traffic and any special source of pollution, no special attention was paid to the problems of outdoor air pollution. AIR-CONDITIONING AND MICROBIOLOGICAL ENVIRONMENT IN THE LECTURE ROOM