English

This paper presents an on-going research programme about the performance of a natural ventilation system in a 3-storey building (with 2 aparments in every floor) in Portugal.

An innovative thermal comfort meter has been developed. It can simulate the human body evaporative losses. The sensor has been calibrated in a climatic chamber with different air temperature, velocity and humidity.

This paper demonstrates the importance of the combined use of an energy simulation program and a CFD program for an accurate design of two low energy cooling systems : displacement ventilation and a combined chilled ceiling with displacement ventilation.

A simple conceptual approach to room surface convective heat transfer is presented, defining a global room heat transfer coefficient. It is applied to two room ventilation systems : mixing and cross-ventilation.

Calculations using CFD are presented for adventitious openings in which the flow is not fully developed. It is shown that the quadratic equation performs significantly better than the power law i.e. a recent claim that the power law equation is preferable to the quadratic equation under such circumstances is not supported. Other recent claims that have been made to support the power law in preference to the quadratic are also examined and reasons are given as to why they are unfounded for conditions of typical, naturally driven air infiltration.

This study is divided into 2 parts : 1. Discussion of the theory of a measurement method for configuration factors using reflections of a curvilinear mirror.2. Estimation method of configuration factors for medium/large scale spaces that can be used instead of methods using the diagrams.

This paper defines a new parameter : the equivalent frequency used for the description of the frequency characteristics of air velocity in turbulent flows.Analyses were performed to identify how much the accuracy of determination of the equivalent frequency depends on the characteristics of the velocity. Results of the analyses identified that the equivalent frequency of the velocity fluctuations in rooms is between 0.1 et 1 Hz, and 90 % of those records were between 0.2 and 0.6 Hz which is the frequency range identified to have most significant impact on people's draught sensation.

Three methods : step-up velocity change, step-down velocity change, and the cut-off frequency method were tested for the dynamic response of two low velocity thermal anemometers.This paper had the objective to identify whether those methods recommended in the standards and guidelines always succeed in determining accurately the frequency response curves and the time constant of low velocities anemometers.

This paper deals with two general approaches used to determine multizone air flow by tracer gas experiments : a tracer gas decay model and a simultaneous release of n different tracer gases in n zones (n x n approach) . The results show a suitable agreement between the model and measurements made, at work-time, in a 3-store building equipped with an hybrid ventilation system.

The deposit of particles on ceilings close to ventilation outlets is mainly caused by the features of mixed ventilation, turbulence and induction. This study aims at solving that annoying problem of particle deposition, for the ventilation industry. The development of a clean outlet is eased thanks to a new experimental approach using an optical technique (in so far as the experimental technique and the CFD calculations are too inefficient).