English

Laboratories with chemical fume hoods can have HVAC systems designed for variable air volume (VAV) for the optimum in safety and cost savings. Various VAV designs are discussed with their associated advantages and disadvantages. Controls for providing VAV operation of fume hoods are outlined. A computer simulation of the energy usage for constant vs. variable volume hood operation is performed. The energy and cost savings are discussed along with a construction cost comparison of constant volume with variable volume.

The Sick Building Syndrome (SBS-syndrome) as defined by a WHO working group is discussed, and the existence of a sub syndrome is postulated, based on observations reported in the literature. This sub syndrome relates mucous membrane irritation - sensory irritation, dryness in nose and eye, which are very frequent symptoms within the Sick Building Syndrome - to the totalconcentration of volatile organic compounds (VOC) of the solvent type. This VOC syndrome may include other until now unidentified symptoms.

Too high a concentration of certain gases (e.g. water vapour, carbon dioxide, tobacco smoke, alcohol, etc.) in public buildings can damage the health. Even low concentrations can cause discomfort and make the room air seem unpleasant. This paper describes this subjective perception of air qulaity. It is shown that installation of an appropriate sensor can make substantial energy savings.

Ventilation by displacement is described in terms of ventilation efficiency and quantified by means of a two-zone flow and diffusion model. The practical procedure is by means of adequate diffusers firstly, to 'hit' the persons with the ventilation air and secondly, to displace both air and contaminants out of the zone of occupation and avoid recirculation. This procedure has a firmbasis in the research work on ventilation efficiency that is carried out inNorway and Sweden during the last years as well as in current theory practice.

The advancement of tracing techniques enabled the problems associated with local and general ventilation in industrial premises to be tackled with accuracy. The purpose of this article is to present, on the one hand, the various measurement techniques of helium tracing used by the CEA and the INRS and, on the other hand, to give some examples of application.

The computer-aided ventilation system design requires the programming of a large number of empirical tables and observations on the use of mathematical expressions which describe numerous ventilation parameters. In order to use computers with efficiency and to reduce programming inessentials, a set of numerical approximations are developed. These expressions are divided intotwo categories: 1) external variables and 2) system variables. The external variables are basically the duct resistance calcultions.

This paper presents a numerical study of instationary three-dimensional flows. Three methods, a semi-implicit one and two explicit ones were compared and tested on typical flow configurations (lid driven cavity, natural convection and mixed convection in a cavity). These methods were then applied to a problem of ventilation in a paint-booth. The semi-implicit method proved to have a higher accuracy. The explicit method of the M.A.C. type turned out to be more advantageous in calculation time.

In order to reconsider the ventilation requirment in office environment and air environmental indices to determine it, field measurements were carried out. The amounts of outdoor air taken into air conditioning system were controlled in three levels and the concentrations of various indoor airpollutants were measured. It was found conclusively that 30 cubic meters per hour per person of intentionally introduced outdoor air was appropriate for ventilation requirement for offices and carbon dioxide was also appropriate as an index.

This paper gives a presentation of the current research being carried out at NSIB with the aim of exploring the effectiveness of ventilation systems in controlling contaminant levels. The key concepts used for quantifying the performance are; the age distribution of both air and contaminants. The air exchange effective- ness and the average ventilation efficiency are derived from the age distributions. Measurements of the performance of different ventilation s systems are given, expressed in terms of the key concepts above.

The relationship between the observed concentration of air pollutants at points within a building and the characteristics of the ventilation system is examined, and a basic set of analytical expressions showing these relationships is presented. The extension to large and complex systems is considered, and an example of the application of the equations to an actual air quality problem is given.