The air velocities and air temperatures distributions within the occupied zone of a room were determined and the wall surface temperatures were measured, in steady-state conditions. For each one of the 5 selected comfort criteria, and at every point of a three-dimensional network, a comfort index, derived from the physical measurements, characterizes the level of discomfort. The data is then synthesized in the form of a comfort profile, taking into account not only the frequency of the 5 types of discomfort, but their intensity as well.
Air flow in an enclosed space, whether from natural or mechanical ventilation, has generally a rather slow velocity, 0.1-0.25 m/s, but may still cause local discomfort. Tests were carried out on laminar and turbulent air flows in this velocity range. Turbulent air flow was found to always cause more discomfort than linear air flow.
This paper discusses the thermal effects of air flows, and some aspects of the influence of moisture and moisture transfer on the thermal performance of a structure. Mathematical and physical modelling of simultaneous coupled heat and mass transfer in porous materials based on the volume averaging technique has been used to analyze these phenomena.
Substantial work on ventilation effectiveness has been carried out in Norway and Sweden using tracer gas techniques based on fundamental physical and mathematical concepts. The nature of, and how to characterize by using tracer gas techniques, the flow of ventilation air and contaminants through a ventilated room is known. Displacement flow has been proved to be the best flow principle for ventilation, and in general ventilation air should be supplied to the occupied zone.
Gives detailed results of an extensive programme of wind tunnel testing of a standard scale model of a one-room, flat-roofed building. A major requirement was coverage of those characteristics of window openings or window accessories which were known (or which appeared) to have a significant effect on indoor air flow.
This paper describes part of a research on the influence of environment on physiological reactions and thermal comfort. Experimental rooms and apparatus are described and the imperfections in some of the instrumental methods - especially in respect to the measurement of air change by tracer substances - are noted. A brief description of a method to measure air change is givenin which CO2 is used. The importance of limiting the rate of air change in rooms heated by fires - as a means to save heat - is stressed.
The multiple tracer gas technique of I'Anson et al. has been improved, in order to increase the rate at which samples can be taken. Using parallel gas chromatographic separation columns and an electron capture detector, it is now possible to take an air/tracer gas sample every thirty seconds in the case of a two-zone ventilation and air movement test. Rapid sampling enables a new,simplified analysis of the air movement between two connected zones to be employed. This analysis derives ventilation rates and intercell airflows simultaneously.
A large proportion of heated rooms depend primarily on natural convection for the distribution of heat within the occupied zone. A method of predicting air temperature variations with height is presented. Using the heat and mass flow rates of the driving convection plume, along with the corresponding parameters of downward flowing air streams at cool surfaces, an estimation of the maximum (upper) temperature and the minimum (lower) temperature can be made. Incoming air entry points can also be taken into account.
This paper reports the findings from tests undertaken in an untight, two-storey, brick-built detached test house. Different ventilation schemes were in use: natural ventilation and mechanical ventilation (both extract and balanced ventilation).
A multicell air flow computer program is used to determine the influence of 1) open windows and 2) closed internal doors on the ventilation rate of a semi-detached house. The changes in interzone air movement and room air change rates are also examined. Tracer gas field measurements used to validate the multicell program show good agreement with the predicted values. Results show that opening windows can alter significantly, not only the overall ventilation rate of the building, but also the individual air change rates in rooms.
Login