draughts

Presents a chart for predicting the percentage of dissatisfied people due to draught in ventilated spaces, based on the results of a research project on perception of draught.

Characteristics of the air velocity were measured at 500 points in the occupied zone of 20 typically ventilated spaces. A relationship between the mean velocity and the standard deviation was found at four heights above the floor. The turbulence intensity varied from 10 to 70% at ankle level (0.1 m) and from 20 to 55% at head level. This is similar to the experimental conditions under which the draught chart by Fanger and Christensen was established.

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.

Presents a mathematical model for the measurement of thermal comfort. Compares the results with previous measurements of air velocity in buildings with and without air conditioning.

The physical reason for draughts is in the first place the convective surface-heat-transfer coefficient. To find out about the influence of turbulence on draughts, it is necessary to carry out measurements of the surface-heat-transfer coefficient in relation to air turbulence. The results of first measurements of this kind are the subject of this paper.

In this paper a hypothesis is set up for explaining the discrepancies between the relatively high acceptable air velocities found during many earlier climate chamber tests, and the much lower acceptable velocities found under many practical circ

One hundred subjects were exposed to air velocities fluctuating in the same manner as in typically ventilated spaces in practice. Each subject participated in three experiments at 20, 23 and 26 degrees C, dressed toobtain a neutral thermal sensation. In each experiment the subject was exposed to six mean velocities from 0.05 to 0.40 m/s. He was asked whether and wherehe could feel air movement and whether it felt uncomfortable. A relation was established between the percentage of people feeling draught and the mean velocity. The subjects were most sensitive to draught on the head region.

Research was undertaken to provide buildings equipped with mechanical exhaust ventilation systems or natural ventilation with reasonable draught-free efficient ventilation. One possible solution for existing detached houses and multi-storey residential buildings is a supply air window. Recent research in Finland shows that, for the best method, about 6.0 dm3/s of outdoor air per light area m2 can be taken in through the wooden construction double-paned window without draught. The incoming air was heated to about 50% of thetemperature difference between the inner and outer air.

Describes a survey of standard homes built between 1907 and 1973, not fitted with double glazing, to assess potential draught gaps, and of consumer attitudes to insulating products particularly draught excluders.

Demonstrates that complaints by office staff about their physical environment are not necessarily caused by physical deficiencies. Trying to reduce the level of complaints by adjusting heating ventilating and air conditioning (HVAC) systems can therefore be an unrewarding task. Greater attention needs to be placed on - communications between management, those responsible for running HVAC systems and staff. Staff need the feeling that they can influence, if not control, their environment. Staff should also have more realistic expectations about their thermal comfort.