This paper deals with the development and the evaluation of hybrid ventilation control strategies, using both natural and mechanical mode, in residential buildings. The case study is a single dwelling and it includes a mechanical ventilation system based on the french national regulation and a hybrid ventilation system used in the framework of the European project RESHYVENT. Two demand control strategies have been developed for hybrid ventilation system, the first one is based on the occupant detection and the second one is based on the CO2 levels in the dry rooms.
The potential for error when using computational fluid dynamics (CFD) for investigating internal building airflows continues to be a critical issue in building simulation analysis. This topic is assessed in the current paper by examining the ability of a proprietary CFD code to simulate buoyancy and forced airflow regimes, typical of a naturally ventilated building. This issue is motivated by an ongoing research project, aimed at examining the relationship between external microclimate and internal building comfort, where CFD constitutes a major analytical tool.
The objective of this study is to evaluate the potential of two inertial ventilation techniques (buried pipes and thermal phase-shifting) for passive cooling of buildings in Brazilian climates. Using EnergyPlus, a typical residential building was simulated in two locations (Sao Paulo and Florianopolis). Simulations consider 5 alternatives of passive cooling, combining different scenarios of controlled direct ventilation, buried pipes and thermal phase-shifting. Results show the potential of these techniques in freefloating as well as in air-conditioning mode.
The issue of this paper is to present theoretical results for a solar chimney with thermal mass, where the glass surface is replaced by photovoltaic (PV) modules. A portion of the heat absorbed by the PV modules is dissipated to the air channel in convective form, and it exchanges radiation heat with the concrete wall. These cooling phenomena for the PV modules improve their efficiency with a lower working temperature. Both phenomena are heating process to the air and the concrete wall, that produce natural ventilation. The solar chimney is supposed to be isolated from any building.
The performance of natural, mechanical and hybrid ventilation systems was monitored, using the tracer gas decay method, in three typical apartment buildings located in two street canyons, during summer period 2002 in Athens. The multi-zone methodology has been adopted based on the mass balance of two tracer gases (N2O and SF6) to define the air change rates. The air-exchange efficiency was determined for different ventilation systems, on the basis of the room mean age of air.
In order to perform detailed evaluation on the applicability of local dynamic similarity concept, which is described in Part 1, wind tunnel experiment was conducted under some conditions where the opening positions and the arrangement of buildings were changed in more complicated manner. As a result, it has been found that the discharge coefficient Cd can be predicted accurately from PR* for the most of opening positions, even if the approaching flow angle is varied or another building is standing near the opening.
This paper presents some results of the research project "Domestic Violence and Architectural Space", sponsored by several Mexican Governmental Offices and Citizen Organizations. One of the purposes of this project was to find the probable correlation between several physical characteristics of houses and violent behavior of their inhabitants. In this paper we report the results of the indoor climate exclusively.
The architectural decisions for building that use natural ventilation should be taken in the initial stages of design when little information is available. A new approach is to compare the potential natural ventilation of known buildings in a new site and to adapt the design of the known example. The potential of natural ventilation may be changed by the barriers to its application: reduced wind velocity, higher temperatures, noise and pollution. Simple models, constructed on measurements, give an indication of the influence of these barriers.
A method is proposed to assess the natural ventilation potential by taking into account the most comprehensive set of factors involved in natural ventilation. These factors are either driving forces, such as wind pressure and stack effect, or constraints, like noise pollution and atmospheric pollution. The process considers these factors in an ordinal qualitative scale and gives its result in this same scale. This bypasses the problem of the inaccuracy of some parameters, which can be very high, especially in urban environment and in the predesign phase of a construction project.
The microclimate and dispersion in urban street canyons has become a subject of intense scientific research in recent years since complex flow patterns evolve leading many times to bad comfort conditions for the pedestrians and the habitants. Within that frame, the main aim of this study is the creation of a semi-empirical algorithm for accurate wind speed computation inside street canyons. A big experimental campaign took place in Athens in the summer of 2001 where measurements were taken in five different urban street canyons in the framework of the Urbvent European Research project.
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