English

In 1998 the Dutch ventilation industry launched a new generation of domestic ventilation systems on the market with high efficiency heat recovery applying counter flow heat exchangers and DC fans. It is expected that these ventilation systems will play an important role in realising the goals of the Dutch national energy policy for reducing energy use in the built environment. Another important aspect is the contribution to a healthy indoor environment in dwellings with an extreme high energy efficiency, especially in relation to increasing air tightness and thermal insulation.

In order to assess the real performances of different demand controlled ventilation (DCV)systems, two of them were installed in meeting rooms of an office building.The first system is controlled by movement detection on terminal units and has been installedin a small meeting room which is regularly used.The second system is controlled by CO2 detection and frequency variation on fan. It has beeninstalled in a large meeting room (30 persons seated, up to 50 persons standing).The systems have proved to be energy saving with correct CO2 levels.

A hybrid ventilation system is a two-mode system that can automatically switch between passive and mechanical mode at different times of the day or seasons of the year. Some ventilation systems, including the hybrid system, have been set up in a full-scale test house constructed in Tohoku University, Japan to assess their performance. In this paper, the performance of each system is described by giving measurement results.

Ventilation needs in dwellings must be determined on the basis of both requirements to theindoor air quality and necessary control of moisture conditions. As a first step towardsdevelopment of energy efficient ventilation strategies for demand controlled ventilation infuture dwellings theoretical analyses comprising a literature study and mathematicalsimulations have been carried out.

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.