Urban air quality makes headline news, and a recent Royal Commission report has stepped up the campaign against pollution from road vehicles. Better detection methods and monitoring mean that we are learning more about the air that we breathe.
Airtightness measurements are not yet common in the Italian dwelling stock. In the frameworkof the MICA-ENEA contract, three dwellings were chosen to study the energy performanceon the influence of natural agents. The majority of the dwellings in Italy still nowdays rely onnatural ventilation and records of the fluidynamic and energy performance are not contractualdocuments among the parties involved.
This report describes various measurement protocols to be used in the measurement of air change rates in non-residential buildings. The measurement protocols are based on the use of tracer gas techniques.
A comprehensive investigation was made of the dynamic behavior of five low-velocity thermal anemometers with omnidirectional sensors. Both the shape of the dynamic response curves of the instruments and their dynamic response were different. The dynamic response of the anemometers was mainly influenced by the frequency of the velocity fluctuations and only slightly by the mean velocity of the airflow and the amplitude of the velocity fluctuations.
Thermal anemometers with omnidirectional sensors are recommended in the standards to be used for low-velocity measurements indoors. Requirements for the directional sensitivity of the velocity sensor are prescribed. However, a method for testing the directional sensitivity of low-velocity anemometers does not exist. A simple test procedure is used in practice to identify the so-called "yaw" and "roll" directional sensitivity of an omnidirectional velocity sensor.
In this paper, new requirements for the characteristics of anemometers used for low-velocity measurements indoors, as well as requirements for the signal processing, are presented The static calibration, dynamic response, and temperature compensation of the anemometers, as well as the directional sensitivity and the design of the velocity transducer, are considered, together with the period and the sampling rate of the measurements.
A study was made of the impact of well-documented random velocity fluctuations and periodic temperature fluctuations with different amplitudes and frequencies on the accuracy of the mean velocity and the standard deviation of the velocity measured by three low-velocity anemometers with omnidirectional probes. The anemometers were tested in an airflow at 225 combinations of mean velocity, amplitude of the velocity, and temperature fluctuations, as well as frequency of the temperature fluctuations, as identified during field measurements.
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