English

Thermal comfort in ventilated spaces depends mainly on air temperature, air speed and turbulence intensity. Mean air speed is commonly measured with omnidirectional hot sphere sensors, whereas directionally sensitive measurement instruments and CFD-simulations normally give the mean velocity vector. The magnitude of the mean velocity vector in turbulent room air flows can be much lower than the mean air speed due to different time averaging processes. This paper studies the difference both experimentally and theoretically as a function of turbulence intensity.

The present work concerns the measurement and the computational fluid dynamics (CFD) modeling of buoyancy-driven air flow through a stairwell that connects the two individual floors of a residential building. A series of experiments was performed in order to study the mas and heal transfer between the two floors. Air flow rates through this stairwell were measured using a single tracer gas decay technique. The analysis of results provided relations which can predict the mass and heat flow rate as a function of the inter-zonal average temperature difference.

This work deals with experimental investigations on human reaction to local air movements of people in global thermal comfort, performing light activity. An analysis on draught risk was developed comparing the results with previous research findings on human response to draught. The intensity of air velocity, in terms of mean value and relative turbulence, was referred to the level at which normally clothed people could perceive and feel air movements behind the neck, in global neutral thermal condition.

The evaluation of the ventilation effectiveness and thermal comfort for various industrial ventilation schemes has been carried out by 1:4 scale model experimentation. Measurements of air speed, temperature, and contaminant concentration allowed the contaminant removal and thermal comfort to be quantified using ventilation effectiveness and thermal comfort indices, respectively. Archimedes number scaling was used to convert the small scale measurements to full scale conditions. The ventilation efficiency generally increased when the heat load was increased and/or the flow rate decreased.

As heat exchanges through building envelopes and undesirable internal gains have been reduced in the last years due to energy conservation efforts, the importance of the energy needed to heat, cool and move outdoor air for ventilation has increased in relative tem1s. This study, developed within the European project TIP-VENT (JOULE) aims to study the impact of ventilation air flow rates upon the energy needs of typical buildings. Five real buildings were selected as case-studies: A hotel, an auditorium, an office building, a single-family residence and an apartment building.

Environmental and economic concerns linked to conventional heating, ventilation and air-conditioning systems (HY AC) have sparked a renewed interest in natural ventilation, passive cooling and other low energy microclimate control strategies for buildings. In Canada, the combination of extreme weather conditions, wind variability, transient occupancy patterns and high internal heat gains may hinder the feasibility of implementing natural ventilation as an exclusive means of ventilating non-domestic buildings.

Traditionally, prediction of ventilation systems performance has been based on deterministic approach, which implies that the spread of the input parameters values is zero. The deterministic approach is valid if the effect of fluctuations in the forcing functions (wind speed and direction, temperature, radiation, occupants' behavior, etc.) is negligible when compared to the mean value.

This paper briefly outlines the development of a design tool for ascertaining thermal comfort in high rise buildings in the tropics. The design tool, based on wind tunnel studies and computational fluid dynamic (CFD) simulations, was then applied to four cities in the tropics: Kuala Lumpur, Singapore, Jakarta and Hong Kong. Can thermal comfort be achieved using solely natural ventilation? The overall conclusion was that natural ventilation alone cannot generally provide thermal comfort in high rise buildings in the tropics.