We propose a new approach for measuring ventilation air exchange rates (AERs). The method belongs to the class of tracer gas techniques, but is formulated in the light of systems theory and signal processing. 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. Using a naturally-ventilated residential apartment, AERs obtained using the new method compared favorably (within 10%) to those obtained using the conventional CO2 decay fitting technique. The new method has the advantages that no tracer gas injection is needed, and high time resolution results are obtained.
Active noise-reducing (ANR) headsets are available commercially in applications varying from aviation communication to consumer audio. Current ANR systems use passive attenuation at high frequencies and loudspeaker-based active noise control at low frequencies to achieve broadband noise reduction. This paper presents a novel ANR headset in which the external noise transmitted to the user's ear via earshell vibration is reduced by controlling the vibration of the earshell using force actuators acting against an inertial mass or the earshell headband. Model-based theoretical analysis using velocity feedback control showed that current piezoelectric actuators provide sufficient force but require lower stiffness for improved low-frequency performance. Control simulations based on experimental data from a laboratory headset showed that good performance can potentially be achieved in practice by a robust feedback controller, while a single-frequency real-time control experiment verified that noise reduction can be achieved using earshell vibration control.
Highlights Summary of recent developments and work at ADAI's Energy, Environment and Comfort research group is presented The Indoor Live Lab (I2L) and an e-learning course on Indoor Environmental Comfort in Buildings are introduced The paper aims to present the facilities, instruments and the purposes behind I2L project Several Indoor Environmental Quality (IEQ) parameters studies are discussed in particular 1
AbstractIn this paper some of the recent developments and ongoing work at the Energy, Environment and Comfort research group of ADAI (Association for the Development of Industrial Aerodynamics), in the areas of Indoor Environmental Quality and Energy Efficiency in Buildings are presented. Summarily, it is showcased a state of the art of the Indoor Live Lab, developed at the Mechanical Engineering Department of the University of Coimbra.
The Indoor Live Lab (I2L) is a new platform for research and technology demonstration in IndoorEnvironmental Quality (IEQ). The main motivation for initiating this effort arose from the increasing necessity that researchers, educators and decision makers have for continuously available monitored data on all aspects of building functioning. This paper aims at presenting early developments at the I2L, as well as associated research projects which were at the centre of its creation. Firstly, the objectives of the I2L are presented. Secondly, ongoing research on both residential buildings and services buildings is exposed. After, the several IEQ parameters studies are discussed in particular. This is followed by the I2L description, location and specific features. Finally, a conclusion and future work section is presented.
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