As the global population becomes more concentrated in urban environments, higher numbers of people will be exposed to urban air pollution. The environmental and human health benefits of green roofs ...are widely recognized. The aim of this paper is to promote green roofs as an effective passive technique for pollution mitigation and adaptation to climate change. During the heating season, the ambient concentrations of PM1, PM2.5, and PM10 were measured above a green roof and a reference roof on a school building, located in New Belgrade, the second-most populous municipality and business center of Serbia’s largest city. The percent reduction of PM10, PM2.5 and PM1, in January 2020, above the green roof compared to the reference roof was 7%, 16.6%, and 17.6%, respectively. The results show that lightweight green roof improve air quality in terms of PM concentrations for all months considered. In this paper, correlation analysis and the use of Pearson’s coefficient were used in the process of analysis to determine the relationship between PM10, PM2.5, PM1, and ambient parameters: relative humidity, ambient temperature, and wind speed. It was found that the statistical correlation expressed by the Pearson coefficient between all PM particles and wind speed was statistically significant in all observed months except September. Also, the degree of significance of the correlation between PM particles and humidity and temperature of ambient air varies by month.
Green roof systems have become an important part in creating sustainable cities. They can provide a wide range of economic, environmental, and social benefits. The goal of this research was to ...quantify the thermal performance improvements from a green roof with mineral wool substrate installed on a school building in a humid subtropical climate. In-situ measurements during a summer period included heat fluxes through the green and reference roof, vertical temperature profile through both roofs, the local air temperature above roofs, and local meteorological parameters. Furthermore, the summer thermal performance of green and reference roof and the green roof cooling effect were evaluated concerning meteorological parameters using the Pearson correlation analysis. The results indicate that the green roof layers have improved thermal performance of the roof with respect to reduced conductive heat flow by 57% and delayed heat transfer. The maximum and averaged reference roof to green roof outdoor surface temperature difference was 27.5 °C and 5.5 °C, respectively. It was found that ambient temperature and relative humidity have a dominant role on the thermal performance of the green and reference roof, while solar radiation and ambient temperature present the key meteorological determinants of the green roof cooling effect.
•The summer thermal behavior of lightweight green roof was experimentally investigated.•The influence of meteorological parameters on the green roof cooling effect was explored.•The green roof with mineral wool substrate decreased heat flow through the roof by 57%.•Green roof reduces the temperature amplitude of outdoor roof surface by 83%.
An inter-laboratory comparison has been performed between seven participants on thermal diffusivity measurements by the laser flash method in the temperature range from 23 °C to 3000 °C. The main ...objective was to assess the variability and coherency of thermal diffusivity measurements performed at ultra-high temperatures at the European level. Three refractory materials (molybdenum, tungsten and isotropic graphite IG210) were selected for this inter-laboratory comparison, due to their high melting point. The disk-shaped specimens needed were machined from the same blocks of materials in order to reduce any potential scattering of results between participants due to inhomogeneity effects.
The homogeneity of the sets of specimens was studied by the pilot laboratory (LNE) before launching the comparison process. Thermal diffusivity measurements were then carried out by the seven participants on the three materials during two successive thermal cycles up to the maximum temperatures that can be reached by the devices used. The analysis of results showed a good agreement between the participants for temperatures above 400 °C, with relative deviations within the uncertainties of measurement and lower than ± 4 % for molybdenum, ± 5 % for isotropic graphite and ± 9 % for tungsten.
This work presents the development of an experimental setup for measurements
on of thermal conductivity of solid materials, such as ceramics, polymers,
rubbers, glasses, biological materials, etc. ...whose thermal conductivity lies
in the approximate range between 0.1 and 2 Wm-1K-1. The setup was designed on
the principle of the single-sided guarded hot plate method. In order to find
the optimal design for generation of traceable one-dimensional heat flux
through an investigated 300?300 mm2 specimen, a numerical heat transfer FEM
analysis was performed. The principal components of the measuring apparatus,
such as hot plate with thermopile, cold plate and auxiliary hot plate were
constructed according to the obtained results of simulations. Software for
the control of experiment and data acquisition was developed using the
LabVIEW programming environment.
nema
This paper presents design, development, and testing of a custom-made calibration environment for the calibration of temperature sensors applied in a guarded hot plate apparatus for thermal ...conductivity measurements. Description of an in situ calibration principle and realization are introduced. Results of numerical simulation, as well as those of experimental validation are given in a separate section of the paper. According to the results, proposed in situ calibration by using the applied guarded hot plate apparatus elements improves both accuracy and traceability the of thermal conductivity measurement
The paper presents a method used in the Vinca Institute of Nuclear Sciences
for a reliable and traceable relative humidity calibration in the temperature
range from 5?C to 45?C. Inside a controllable ...temperature and humidity
environment, supplied by a mixed-flow humidity generator, measurements of
hygrometers under calibration are compared with those of calibrated reference
instruments. A traceability chain from temperature to reference relative
humidity and next to the hygrometers under calibrations is provided by using
a chilled-mirror dew-point temperature system and precise relative humidity
probes. Corresponding calibration uncertainties are analyzed, particularly
those associated to the temperature uniformity of controlled calibration
environment. Two examples of relative humidity calibration with dew-point and
relative humidity reference measurements in the range from 15 to 75% of RH
and 5?C to 45?C are presented and discussed.
nema
This work presents a software solution for adjusting, controlling,
displaying, and acquiring parameters and data in the pulse calorimetry
experimental technique for specific heat capacity, electrical ...resistivity,
total hemispherical emissivity, and normal spectral emissivity measurements.
The software has been developed under the LabVIEW platform, V.7.11, and an
example of its application with measurement results is presented in a
separate section. The total expanded uncertainty of obtained results for the
specific heat capacity and electrical resistivity of palladium was 5% and 1 -
2%, respectively.
nema
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