This paper presents an analysis of indoor climate in buildings with forced air heating systems. The results is based on indoor climate measurements and extensive interviews with the occupants. The analysis shows that design criteria is of great importance for the occupants conceptions of thermal comfort in buildings with air heating systems. Forced air heating systems could be a way to provide mechanical supply air with less problems with the thermal comfort, such as draught, than in ordinary supply- and exhaust air ventilation systems.

Traditionally air has been supplied from the ceiling to the occupants below opposing the buoyancy effects due to heat convected from people, lights and machines. There has also been concern that if air supply outlets are installed at low level near people the chances of draughts and noise are high. The development of swirl air diffusers in Sweden and Germany overcomes these problems and allows a wider consideration of air distribution systems when designing buildings. This also offers flexibility in planning the distribution of electrical systems and piped services.

The paper describes measuring results of the air movement from three different types of diffusers for displacement ventilation. Two of the diffusers are lowlevel wall mounted diffusers, one with a low and one with a high initial entrainment. The third diffuser is of the floor mounted type. The air flow close to the diffusers and in the rest of the room is analysed. Velocity decay in the flow from the low-level diffusers is given as a function of the Archimeaes number, and the paper suggests a general equation for this part of the flow.

The project is aimed to develop the quantitative method of visualization of the air steams in application to the indoor problems of heauilg , ventilating and air conditioning. The geometrically well defined light sheet is crossing the examined space and determines the plane of observation. The photographic camera is placed perpendicularly to this plane at a distance of a few meters. The flow is seeded with the soap bubbles of the diameter 3-4 mm. The light is reflected from those bubbles which are crossing the illuminating sheet.

In the past few years, research efforts have been made to acquire accurate knowledge about infiltration and ventilation in multi-zone buildings. By this way, a wide variety of modelling techniques have been developed which suffer of a lack of satisfactory validations. The purpose of this work is to set up a data bank of high quality measurements which will serve to cany out an empirical validation of multi-zone air infiltration programs. Among other data, a complete set of air flow permeabilities of a well known experimental midsize building will be included to this bank.

The problem of predicting air flows in a multi-zone building has received considerable attention in the past ten years. An important issue identified by this work was the lack of reliable measurements of the flow resistances between the zones of such buildings. This report analyzes the uncertainties associated with a fan-pressurization technique for measuring the interzonal leakage (inverse flow resistance) in a multi-zone building. The technique involves two blower doors, one in each of the two zones between which the leakage is being measured.

The technique of tracer gas measurement has during recent years tended towards increasingly complicated measuring methods. The new measuring techniques are essential in order to procure more information about the circulation of air through buildings, or in order to perform more accurate measurements in large and complex buildings. The measuring method by means of "constant concentration of tracer-gas", which has been applied at Technological Institute for about 7 years, has proved to be a very accurate measuring method for both small and very large buildings.

A unique multiple tracer experimental system has been developed and utilized within commercial buildings to monitor ventilation rates, air exchange efficiency, ages of air (at multiple indoor locations), flow rates of supply and outside air, and percent outside air in supply airstreams. The multiple tracer technique also makes it possible to determine the fractions of air at a monitoring point that entered the building through a particular air handler and by infiltration.

Tracer gas techniques for measuring airflow rates in building systems are considered. These techniques are classified in terms of tracer gas injection strategy employed and mass balance relationships used to analyze measured tracer concentration data. The discussion focuses on one class of tracer techniques - the pulse injection techniques - based upon pulse injection strategies and integral mass balance relationships.

In displacement ventilation systems, air flow rates, temperature and the design of the air supply device strongly influence the parameters which decide the thermal comfort. This paper reviews experiments and theoretical models which show the connection between t.hese parameters. It is indicated that the Archimedes number of the supply air is the parameter which decides the air velocity in the area close to the floor. (The Archimedes number is the ratio between buoyancy and inertia forces).