Assuming higher than probable cd values for crack length openings on calculation of infiltration rates results in excessive allowances for heating and cooling capacity. Using a given cd graph, proposes equation to determine infiltration rates and reduce internal pressurization requirements to offset wind impingement.

A number of cases of water and frost damage in masonry and non loadbearing walls have been examined. This damage could not have resulted from vapour diffusion or rain penetration and is primarily caused by condensation due to exfiltration of air. Air exfiltrates through the many cracks and joints and in this connection the result of chimney action and wind is explained in some detail, including the pattern and magnitude of building pressure differences that induce ex-filtration together with a discussion regarding the moisture that is transferred.

Using nitrous oxide as a tracer, the author made 390 measurements of ventilation rates in seven closed rooms of six houses, in Melbourne, Australia. Half of the observations were taken when the wall ventilators were sealed, in order to explore their influence on room ventilation. Results for each room, grouped in ranges of wind direction and according to whether ventilators were open or closed, are shown as regression curveson plots of ventilation rate against wind speed. The ventilators are shown to have only a slight effect on ventilation.

In a lecture held for T.V.V.L. members on 22nd November 1965, the influence of wind, direction of the wind and wind force on buildings were described showing the resulting pressure distribution around the building and the general effect of wind on buildings which are ventilated either naturally or mechanically. The influence of wind on a specific building can be determined by pressure measurements, for instance in a windtunnel. This is followed by measurements with an electric analogue in which light bulbs give an indication of the air movement.

For simplicity's sake the determination method outlined in previous issues of this article did not include the air infiltration through cracks. The graphical method is again demonstrated when allowing for air infiltration as specified in German standard DIN 4701 and examples are given.

Points out mistakes in text book formulae for determining the flow rate of fresh air. Provides a new approximate formula for this. Establishes a differential equation for air change rates and derives a generalized equation for ventilation incorporating only three parameters. Provides curves for determining the fresh air flow rate and gives calculated examples.

Reports a theoretical study of natural ventilation made jointly by HVRA (UK) and Institute for Public Health Engineering TNO (Netherlands). Uses analogue and digital computers, and results so derived were used to produce a design method suitable for rapid assessment of the natural ventilation of projected buildings. Shows this method to be quicker, cheaper, and more accurate than the crack method (measured leakage at windows and doors) or the air change method.

Outlines the development of current ideas of effective ventilation from early 19th century when official (U.S.) requirements were unduly high due to misconceptions in health requirements. Examines current requirement.

Reports theoretical and experimental calculations of heat balance of 5 houses. Discusses the extent of air leakage and various factors contributing to heat losses, particularly effects of wind and winter temperatures. Normal air leakage is 0. 5-0.7 air changes/h, mainly through chimneys, air outlets, window, and door cracks. Air leakage of floor, door, and roofs is 0.1-0.2 air changes/h. in winter, temperature differences have the same influence on ventilation as wind velocity. Measurements in attics show 3 air changes/h. This is largely dependent on wind velocity.

Presents a general picture of the consequence of wind on high buildings. States that the air velocity in the lower 250-600m layer of the atmosphere is strongly affected by the shape of the earth's contours, and discusses the effect and size of eddies. Gives the range of wind pressure variations between windward side, leeward side and at corners and edges and outlines problems that can result in ventilating, from draught and other wind hindrance aspects. Brief tips are given to minimize serious mishaps from the result of wind near high rise buildings.