A laboratory investigation has been made in a modern Swedish bathroom continuously ventilated by an exhaust fan. The tests consisted of measurements of the humidity, temperature and local mean-age after a standard shower. The measurements were mainly made in a non-heated installation.

The knowledge of IEA-Annex 14 'Condensation and Energy' has been applied to develop a new strategy for humidity control in dwellings. The presented control element assures safe prevention from mould growth at a minimum energy consumption. The advanced humidity control device consists of a surface temperature and an indoor air temperature sensor, from which readings a microcontroller evaluates the appropriate RH setpoint. A humidity sensor then reads the actual RH in the room air and compares it with the momentary setpoint.

A new algorithm for the continuous measurement of variable air change rates with tracer gases will be presented. It differs from the constant concentration method by allowing the concentration level to vary according to the air change rate. Also the mixing process of tracer gas within the room under investigation is considered and limited measurement ranges and injection rates of the tracer gas equipment can be accounted for. The new algorithm has a number of advantages, such as quick response to variations in the air change rate and reduced tracer gas consumption.

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.

Zonal models are a promising way to predict air movement, in a room with respect to comfort conditions and gradient of temperature, because they require extremely low computer time and may be therefore rather easily included in multizone air movement models. The main objective of this paper is to study the ability of the zonal models to predict the thermal behaviour of air in case of natural convection coupled with a radiator. First, we present simplified two zone and five zone models.

The measurements reported in this paper were carried out in a mock up of an office room, ventilated by a commercial supply air terminal consisting of 84 nozzles (characteristic dimension SqRoot of As = 0.0975 m). The test room configuration was identical to the one used within the IEA Annex 20 work. Results from isothermal supply is reported. A constant-temperature hot-film anemometer with fast dynamic response was used torecord the instantaneous velocities.

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.

The work in this paper contributes to the work in the IEA - Annex 20 "Air Flow Patterns within Buildings" and presents a series of full-scale measurements of the concentration distribution in a room with isothermal mixing ventilation. Vertical profiles of the concentration in the middle of the room have been measured under different conditions. With the contamination source in the middle of the room the vertical profiles were changed radically with an increase of the air change rate from n= 1.5h^-1 to n=6h^-1 due to a change in the flow structure in the room.

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.

Within the frame of the IEA Annex 20, laboratory and numerical experiments were conducted in order to study the flow within an isothermal parallepipedic testroom (L x W x H = 4.2 m x 3.6 m x 2.5 m). The air is injected through a complex diffuser (made of 84 nozzles) near the ceiling and is evacuated through a rectangular exit just below the inlet. While other participants to the Annex 20 made measurements on aeraulic testrooms, we used a hydraulic model scaled to the sixth. The parameters were determined according to a Reynolds similitude.