Matti Pentti

Microbial growth inside insulated external walls as an indoor air biocontamination source.

ABSTRACT The association between moisture-related microbial growth (mesophilic fungi and bacteria) within insulated exterior walls and microbial concentrations in the indoor air was studied. The studied apartment buildings with precast concrete external walls were situated in a subarctic zone. Actinomycetes in the insulation layer were found to have increased concentrations in the indoor air. The moisture content of the indoor air significantly affected all measurable airborne concentrations.

Comparison between European chimney test results and actual installations

European standards regulate the certification procedure for determining chimney class temperature and the distance at which to install chimneys from combustible materials. These standards prescribe the heat stress test and the thermal shock test. The high number of roof fires due to the presence of a chimney that have recently occurred in European countries seems to be due to a weak certification procedure. In this article, experimental tests and numerical simulations have been performed to highlight the major differences between real and test conditions to identify critical aspects of the current certification procedure. The influence of the position of the chimney in the test structure, the thermocouples’ positioning and the thermal shock test initial condition have been investigated. It has been shown that flammable materials’ temperatures measured in the certification procedure can be lower than those in real installations, and this is mainly due to the fact that exhaust gas temperature in the certification procedure of chimneys can be even 350°C lower than in real installations. Then, real installations represent a more severe condition.

Practical Experiences from Several Moisture Performance Assessments

This study analysed the moisture performance assessment reports of 76 buildings: 56 schools, nine healthcare buildings, three daycare centres and five office buildings. The researchers’ practical experiences from moisture performance assessments were also made use of in the study. The aim of this study was to determine the methods used to detect moisture and mould damage in the building stock. The results of the study show that most moisture and mould damage is detected by a surface moisture indicator (Annila et al. in Proceedings of the 1st international symposium on building pathology, pp 115–122, 2015a). That is an important finding since these indicators enable easy measuring of large sections of structures and targeting of more detailed inspections, moisture measurements and material samplings based on mapping with them.

The Effect of Climate Change on Freeze-Thaw Cycles in Nordic Climate

In Finland weather conditions are very aggressive for concrete structures which are not sheltered against rain. One of the most serious issues concerns freeze-thaw cycles when at the same time ambient conditions are wet. This situation is common in Finland during autumn, spring and warm winter when daytime temperature is slightly above 0 °C and by night below.