Spatial variability of soil temperature in an urban area: A case study for a medium-sized European city

Even though soil temperature in urban environment influences a range of processes, it has been studied rather sparsely in comparison with surface temperature or air temperature. Our research extends the soil temperature observation in Olomouc (Czechia) and uses semi-stationary measurement to describe detailed spatial variability of soil temperature in the area of a medium-sized Central European city. Differences in soil temperature 20 cm below grass-covered surface may exceed 3°C due to soil type, shadow cast by buildings and grass characteristics, which means that the representativeness of the data on soil temperature from a meteorological station within a city may be limited. Further research and a conceptual approach towards the study of soil temperature in urban landscape is needed.

Comparison of the Aerosol Photometer and Light Scattering Airborne Particle Counter (LSAPC) Methods for Installed Filter System Leak Testing

The installed filter system leak test method for cleanrooms and clean zones is described in ISO 14644-3, Cleanrooms and associated controlled environments—Part 3: Test method. Portions of the methods in ISO 14644-3 were adapted from IEST-RP-CC034.4[Schaumburg, Illinois, US: Institute of Environmental Science and Technology], which provides a set of recommended procedures for leak testing HEPA and ULPA filters in situ (in the field) with the aerosol photometer test method and the light scattering airborne particle counter (LSAPC) test method. Leak testing is performed to confirm that the final high efficiency air filter system is properly installed by verifying the absence of bypass leakage in the installation, and that the filters are free of defects (small holes and other damage in the filter medium, frame, seal and leaks in the filter bank framework). This study was conducted to compare the aerosol photometer and LSAPC methods. Testing in the study consisted of creating artificial leaks in the filter system, measuring the upstream and downstream concentrations with the aerosol photometer and with the LSAPC, and comparing the filter leak penetration results. Comparison testing was applied to the procedure for the installed terminal panel filter system leakage scan test (stationary measurement) and the procedure for evaluating overall leakage of high-airflow box-type filters mounted in a duct or air-handling unit (AHU) (overall leakage test). It was found that the aerosol photometer and the LSAPC gave similar results for filter leakage within experimental error. The comparison of the leakage scan tests (stationary measurement) showed that the penetration calculated for the channel ≥ 0.3 μm of the LSAPC with an air flow rate of 1cu ft/min (CFM) (28.3 l/min) was very similar to the penetration measured with the aerosol photometer for a leakage level >0.01 % of the upstream concentration. The comparison result of the overall leakage test showed that overall total penetration values, obtained after dilution of artificial calibrated leaks in the filter media, were identical, within the measurement uncertainty, for particles ≥0.3 μm whether the sampling rate of the LSAPC was 1 CFM (28.3 l/min) or 50 l/min. Several recommendations are provided. In particular, for filters mounted in a duct or AHU where the filter function is critical, the recommended method is the leakage scan test method, using a grid sampling method in a plane downstream of the filter (as agreed between customer and supplier).

Mobile Measurements of Particulate Matter in a Car Cabin: Local Variations, Contrasting Data from Mobile versus Stationary Measurements and the Effect of an Opened versus a Closed Window

Air pollution of particulate matter (PM) from traffic emissions has a significant impact on human health. Risk assessments for different traffic participants are often performed on the basis of data from local air quality monitoring stations. Numerous studies demonstrated the limitation of this approach. To assess the risk of PM exposure to a car driver more realistically, we measure the exposure to PM in a car cabin with a mobile aerosol spectrometer in Frankfurt am Main under different settings (local variations, opened versus a closed window) and compare it with data from stationary measurement. A video camera monitored the surroundings for potential PM source detection. In-cabin concentrations peaked at 508 µg m−3 for PM10, 133.9 µg m−3 for PM2.5, and 401.3 µg m−3 for coarse particles, and strongly depended on PM size and PM concentration in ambient air. The concentration of smaller particles showed low fluctuations, but the concentration of coarse particles showed high fluctuations with maximum values on busy roads. Several of these concentration peaks were assigned to the corresponding sources with characteristic particle size distribution profiles. The closure of the car window reduced the exposure to PM, and in particular to coarse particles. The mobile measured PM values differed significantly from stationary PM measures, although good correlations were computed for finer particles. Mobile rather than stationary measurements are essential to assess the risk of PM exposure for car passengers.

Semi-stationary measurement as a tool to refine understanding of the soil temperature spatial variability

Using data obtained by soil temperature measurement at stations in the Metropolitan Station Network in Olomouc, extensive semi-stationary measurement was implemented to study the spatial variability of the soil temperature. With the development of the research and computer technology, the study of the temperature is not limited by the complexity of the processes determining the soil temperature, but by the lack of spatial data. This study presents simple semi-stationary soil temperature measurement methods, which can contribute to the study of the spatial variability of soil temperature. By semi-stationary measurement, it is possible to determine the average soil temperature with high accuracy and the minimum soil temperature with sufficient accuracy at a depth of 20 cm. It was proven that the spatial variability of the minimum soil temperature under grass at a depth of 20 cm can reach up to several degrees Celsius at the regional level, more than 1°C at the local level, and tenths of °C at the sublocal level. Consequently, the standard stationary measurement of the soil temperature can be regarded as representative only for a very limited area. Semi-stationary soil temperature measurement is, therefore, an important tool for further development of soil temperature research.

Transient Pulse Method for Measuring of Heat Conductivity of Autoclaved Aerated Concrete

The heat conductivity, specific heat and bulk density are the basic material parameters and thus indispensable. There are numbers of methods used for measurement of heat conductivity. However, the non-stationary (transient pulse method) measurements methods are preferred for description of heat conductivity moisture dependence. This article discusses on the establishment dependence of heat conductivity on water content for selected porous building materials by using non stationary measurement methods. Dependence of the thermal conductivity on the water content is necessary for coupled heat, air and moisture (HAM) simulation in building construction.

Study of Thermal Technical Properties of Lightweight Concrete with Utilization of Non Stationary Hot-Wire Method

This paper describes the results of research that was focused on the study of thermal insulation properties and behaviour of lightweight expanded clay aggregate concrete. During the research it was carried out a determination of the thermal conductivity on a series of test samples with different volume weight and different mechanical properties. Determination of the thermal conductivity coefficient at lightweight concrete is quite difficult due to high in homogeneousness of the tested material being result of high open structure. Stationary and non-stationary measurement methods were used to determine the thermal insulation properties, which were reviewed for their relevance to the application.