Manuel Gameiro da Silva

Accuracy Limitations for Low-Velocity Measurements and Draft Assessment in Rooms

The measurement of air temperature, mean air speed, and turbulence intensity is required in order to assess air distribution and draft discomfort in ventilated rooms. The measurements are also used for validation of computational fluid dynamics (CFD) predictions. The uncertainty of the measurements must be known in order to perform reliable assessment and validation. At present, a low-velocity thermal anemometer (LVTA) with an omnidirectional (spherical) sensor is most often used in practice for measuring air speed due to its low price and easy and convenient operation. The accuracy of the speed measurement and of the draft risk determination can be affected by numerous factors, for example, directional sensitivity of the velocity sensor, natural convection flow generated by the heated velocity sensor, dynamic response of the anemometer, calibration of the anemometer, velocity and temperature gradients in the flow of measurement, etc. The impact of these factors can be minimized substantially by improvement of the anemometer design, proper use of the instrument during measurement, and correction of the measured data. However, the extent to which the measuring accuracy can be improved is limited. In this paper, the combined impact of error sources on the accuracy of mean speed, standard deviation of speed, and turbulence intensity that may occur during measurements with LVTAs is analyzed. The minimum uncertainty that is realistically achievable in practice is identified. The requirements for low-velocity anemometers prescribed in the present standards are critically reviewed and revised. New requirements that will decrease the uncertainty of low-velocity measurements are suggested for inclusion in future ventilation standards. The uncertainty in determination of draft discomfort is defined. Thus, the definition of realistic requirements in thermal comfort standards as well as validation of CFD predictions is made possible.

Development and Application of Competencies for Graduate Programs in Energy and Sustainability

Educational competencies represent learning objectives and are used to plan educational programs, develop curricula, and assess existing programs, among other functions. After reviewing the literat...

A systematic indoor air quality audit approach for public buildings

Good indoor air quality (IAQ) in buildings provides a comfortable and healthy environment for the occupants to work, learn, study, etc. Therefore, it is important to ascertain the IAQ status in the buildings. This study is aimed to establish and demonstrate the comprehensive IAQ audit approach for public buildings, based on Portugal national laws. Four public buildings in Portugal are used to demonstrate the IAQ audit application. The systematic approach involves the measurement of physical parameters (temperature, relative humidity, and concentration of the suspended particulate matter), monitoring of the concentrations of selected chemical indicators [carbon dioxide (CO2), carbon monoxide, formaldehyde, ozone, and total volatile organic compounds], and the measurements of biological indicators (bacteria and fungi). In addition, air exchange rates are measured by the concentration decay method using metabolic CO2 as the tracer gas. The comprehensive audits indicated some situations of common IAQ problems in buildings, namely: (1) insufficient ventilation rate, (2) too high particle concentration; and (3) poor filtration effectiveness and hygienic conditions in most of the air handling units. Accordingly, a set of recommendations for the improvement of IAQ conditions were advised to the building owner/managers.

Measurement of Infiltration Rates from the Daily Cycle of Ambient CO2

Abstract A new approach for measuring air infiltration rates in buildings is proposed. The method belongs to the class of tracer gas techniques but, unlike conventional CO2 based methods that assume the outdoor ambient CO2 concentration is constant, the proposed method recognizes that photosynthesis and respiration cycle of plants and processes associated with fuel combustion produce daily, quasi-periodic, variations in the ambient CO2 concentrations. These daily variations, which are within the detection range of existing monitoring equipment, are utilized for estimating ventilation rates without the need of a source of CO2 in the building. The new method has the advantages that no tracer gas injection is needed, and time resolved results are easily obtained.

Real time web publishing of environmental noise monitoring data

This paper summarizes the steps that were followed in the creation of a dynamic webpage for publishing, in real time, the data from the Environmental Noise Monitoring station installed at the Association for the Development of Industrial Aerodynamics (ADAI), at the University of Coimbra. The webpage has been used as part of a remote laboratory activity in a distance learning course about indoor environment comfort in buildings, organized by the University of Coimbra.

Measurement and Simulation of Indoor Air Quality and CO2 Concentration in a Hotel Room

Indoor air quality (IAQ) is nowadays universally recognized as an important issue that affects the comfort and health of people, as well as their productivity. This paper describes the relationship of indoor CO2 concentration to building air quality and ventilation, with a focus on how CO2 can be used to evaluate and predict air quality and ventilation performance, namely the infiltration airflow rate. Besides it shows the ability of ESP-r building simulation software for predicting the CO2 concentration and the air exchange rate in a building. For this purposes a room of a hotel located in the urban area of Coimbra was chosen. The developed simulation model was then validated against empirical results. It was shown that a fair degree of agreement between ESP-r results and the experimental observation exist for the zones. High accuracy of the simulation model showed that building simulation software, namely ESP-r can provide a better understanding of indoor environmental conditions and be a powerful tool in finding the best modification measures for improving the indoor air quality in a building.Copyright

Virtual Laboratories for a Course on Indoor Environmental Quality

Abstractâ?? This paper describes a set of software tools developed by the author to support the teaching of a course on Indoor Environmental Quality, given to the Master programme on Energy for Sustainability and PhD programme on Sustainable Energy Systems at the University of Coimbra, which are included on the MIT-Portugal Initiative educational programme. The course includes materials about Thermal Environment, Indoor Air Quality, Noise, Vibration, Lighting and the combined effect of these previous stressors. The software tools were developed both with Microsoft Excel and the programming platform LabVIEW