English

Demand controlled HVAC-systems have many advantages. The principle is to optimize comfort and to minimize energy consumption simultaneously. In modern office buildings, indoor temperature is very often a useful control parameter. Thequestion is, whether it should govern the system for each room individually or for a zone. In the latter case: how shall the zones be defined? Above all, performance criteria have to be weighed against the investment cost. This paper discusses different strategies, which have been or are going to be realized for office buildings.

Is it possible to translate a computed flow field to a design case with different physical dimension? - This and related questions must be answered when the results of the "air flow pattern atlasM, as proposed in the IEA Annex 20, should be applied to actual ventilation systems. Looking up a case in the atlas and transforming results to an actual application is like interpolating in a table. If geometries are similar, scaling laws may be applied. The interpolation problem also arises when numerical or experimental data from literature must be translated to a case at hand.

The present work is an investigation of ground heat exchangers for the air-conditioning of the supply air to residential buildings. To this end, an analytical approximate solution for the temperature field of the ground in which a ground pipe hasbeen laid is derived. This analytical approximate solution is applicable to a free-lying ground heat exchanger consisting of a single ground pipe. Extensions of this solution enable calculations for ground heat exchangers which are laid around a house, or which consist of several ground pipes connected in parallel.

The passive perfluorocarbon method (PFT-method) has been successfully applied in ventilation measurements in rooms. The method is, in principle, also applicable to air flow measurements in ventilation ducts. There are, however, several problems in applying a passive sampling technique in a duct. First, the concentration of the tracer may not be uniform through the cross-section of a duct. Second, the velocities in a duct are normally an order of magnitude higher than in a room.

Kitchen hoods are frequently found in Belgian kitchens. Most of them have as only function intensive ventilation during certain cooking activities. It is expected that kitchen hoods with appropriate performances can also play an important role as devices for guaranteeing basic ventilation. The aims of the research can be summarized as follows: How do occupants evaluate the performance of existing kitchen hoods? What are the sound levels (dB(A)) in various locations in these dwellings due to the kitchen hood?

A commercially available humidity controlled natural ventilation system (Aereco) has been installed in the framework of a CEC demonstration project in 3 apartment buildings in France, the Netherlands and in Belgium. An extensive monitoring campaign in reference apartments and humidity controlled apartments during the 2 previous winters allowed a detailed analysis of various ventilation related parameters. Special attention is given to the evaluation of the humidity control on the performances.

This paper evaluates the suitability of humidity-controlled house ventilation system to determine (i) the effectiveness of relative humidity as a sensing element, and (ii) the operating and performance characteristics of such ventilation strategy. The ventilation system consists of continuously running "mechanical" air extractor units and "passive" air inlet units equipped with humidity sensors. The ventilation system was installed in two single storey houses which were monitored during November 1989 to April 1990.

Seen from the AIVC Technotes 21 and 28, Ventilation Efficiency is still a complex concept. As well for measurements as for simulations. Two more or less separate terms are used: Ventilation Efficiency (-Supply Efficiency) and Ventilation Effectiveness (-Contaminant Removal Effectiveness). In thispaper is shown that the Multizone Ventilation Efficiency has a much wider range than Ventilation Efficiency within one room. In a single room efficiencies can be found for example up to 2 forvery good systems.

We describe the use of constant injection and pulse injection techniques for measurement of airflow in a duct. Tracer-gas measurements were compared with measurements made using a pitot tube and a hot-wire anemometer. Tracer-gas concentration, air velocity and pressure distribution were measured at various distances from the duct wall and inlet. An empirical equation was obtained for the entrance length required to achieve fully-developed turbulent flow and this was compared with measurements made using a pitot tube and hot-wire anemometer.

Knowledge of air movement within a building is often a condition for solving problems with the spread of pollution. The internal airflow paterns are mostly very complex and a survey of the airflow normally demands that measurements are carried out. Measuring equipment for defining air movement within buildings almost always uses the tracer gas technique. We have used two tracer gases and have kept a constant concentration of these in the polluted and the clean zones respectively. Thus enabling us to get a time history of the airflow between the two zanes.