English

Knowledge and estimation of the wind speed and air flow characteristics, in a city, is of vitalimportance for passive cooling applications and especially in the design of naturallyventilated buildings. This study is referred to the analysis of the wind characteristics in urbancanyons as a function of the free stream wind. The impact on the airflow rate calculation isdiscussed for an urban canyon. The goal of this study is to get a better insight of the impact ofthe urban environment on the ventilation effectiveness.

There has been a growing interest in the use of natural ventilation in buildings to supplement orreplace mechanical air supply systems. However, for buildings in busy urban areas the potentialto use natural ventilation can be limited by excessive noise entering through natural ventilationopenings such as windows and trickle ventilators. Such openings tend to have large open areasto enhance air flow while offering a very low resistance to the transmission of external urbannoise.

The estimate of actual air change rates considering atmospheric turbulence isintroduced. The starting point is the spectral description of turbulence - Kaimalspectrum was used in order to consider the height above ground. A set of syntheticwind velocity series are generated, out from a modified spectrum. The procedureconsiders an aerodynamic transfer function (a filter) where peculiar and cut-offfrequencies are determined by the general dimensions of the building and of theexternal openings, i. e., the turbulent scales of interest.

This article describes a ventilation system, developed within the framework of aEuropean project supported by the JOULE III programme (NAVAIR project). Theconcept used - natural ventilation assisted by air induction combines the advantages ofnatural ventilation and the performances of mechanical ventilation.

In this study, computational fluid dynamics (CFD) and a variety of mixing models is used to evaluate the indoor air quality in a small single-family house. CO2, CO, NO2, formaldehyde (HCHO), and vapor are tracked throughout the house to determine the concentration levels, occupational dosing, and personal exposure for a family of two adults and two children. Variations in metabolic activity, smoking, gas stove cooking, and showering make exposure very dependent on the individual's location in the house due to pollutant migration.

Natural ventilation is one of the most fundamental techniques to reduce energy usage inbuildings. However, due to complicated site plans and building layouts, it is difficult todesign optimal layouts for the enhancement of ventilation without knowledge about the flowpatterns. The employment of computational fluid dynamic (CFD) tools in the design processcan give predictive feedback to the designers, allowing them to optimize airflow around thesite to decide on building placement, orientation, and interior space layout.

The Building Air Tightness is an important parameter on ventilation systems performanceand energy losses.Yet, the total amount of leakage is as important on performances as their effective positionin the room.Some calculations have been run according to prEN 13465 from TC156 WG2 for differentbuildings (single house, dwellings and commercial buildings) varying air tightness, valueand repartition for different ventilation systems (natural, mechanical exhaust, mechanicalexhaust and supply).All these calculations have been compared focusing on ventilation losses during heatingseason in Paris.So

In natural ventilation systems, fresh air is often provided through opening of windows, andthere is a wide range of possibilities with regard to selection of window type and position inthe facade. Different window types have quite different characteristics and thereby differentimpact on the thermal comfort conditions in the occupied zone. The thermal comfort is alsovery dependent on the selected natural ventilation strategy, the outdoor conditions and theavailable pressure difference across the window opening.

The operation and performance of forced-air ventilation systems with the aid of a dynamic modeling and simulation computer program are presented. The functions and features of GEMS (Generalized Engineering Modeling and Simulation), a dynamic modeling and simulation software tool, are briefly described. Using GEMS, the effects of different ventilation airflow rates and sensible and moisture efficiencies on the thermal comfort environment within the conditioned space were analyzed.

The development of guidelines for performance based innovative mechanical ventilationsystems in residential and commercial buildings is included in the European Commissionproject TIPVENT Towards Improved Performances of Mechanical Ventilation Systems.The overall aim of TIPVENT is to promote improved performances of mechanical ventilationsystems and the introduction and implementation of innovative designs. The development ofperformance oriented procedures for designing, commissioning and maintaining mechanicalventilation systems plays a key role in the project.